Smart Materials are along with Innovation attributes and Artificial Intelligence among the most used “buzz” words in all media. Central to their practical occurrence, many talents are to be gathered within new contextual data influxes. Has this, in the last 20 years, changed some of the essential fundamental dimensions and the required skills of the actors such as providers, users, insiders, etc.? This is a preliminary focus and prelude of this review. As an example, polysaccharide materials are the most abundant macromolecules present as an integral part of the natural system of our planet. They are renewable, biodegradable, carbon neutral with low environmental, health and safety risks and serve as structural materials in the cell walls of plants. Most of them are used, for many years, as engineering materials in many important industrial processes, such as pulp and papermaking and manufacture of synthetic textile fibres. They are also used in other domains such as conversion into biofuels and, more recently, in the design of processes using polysaccharide nanoparticles. The main properties of polysaccharides ( e.g. low density, thermal stability, chemical resistance, high mechanical strength…), together with their biocompatibility, biodegradability, functionality, durability and uniformity, allow their use for manufacturing smart materials such as blends and composites, electroactive polymers and hydrogels which can be obtained 1) through direct utilization and/or 2) after chemical or physical modifications of the polysaccharides. This paper reviews recent works developed on polysaccharides, mainly on cellulose, hemicelluloses, chitin, chitosans, alginates, and their by-products (blends and composites), with the objectives of manufacturing smart materials. It is worth noting that, today, the fundamental understanding of the molecular level interactions that confer smartness to polysaccharides remains poor and one can predict that new experimental and theoretical tools will emerge to develop the necessary understanding of the structure-property-function relationships that will enable polysaccharide-smartness to be better understood and controlled, giving rise to the development of new and innovative applications such as nanotechnology, foods, cosmetics and medicine ( e.g. controlled drug release and regenerative medicine) and so, opening up major commercial markets in the context of green chemistry.
“The use of biomaterials for industrial applications has increased significantly. Carbon footprints rationalization and food vs. fuel dilemma have been debated and made considerable progress towards a wider acceptance at various levels. Open innovation contributes meaningfully with regards to: softer, milder temperature biochemical processing which includes preconditioning, low stress reactions, “just-as-needed” purifications, zero waste, fallow land exploitation rationalization, usable agri-waste, traceable land use, water consumption minoration vs. agronomical food-related practice, partial detachment from international seasonal trading of agricultural commodities…” [
In this context, our journey across the “rurban” zones is evolving. The sightseeing is a planet “responsible” fairytale that is coming closer to reality; locally produced, synergically codependent energies. Piezo (due for example to the unique crystalline structure and piezoelectric behavior of cellulose as described later in Section 2.2) and solar photovoltaic road paving, quietly growing CO2 harvesting forests, prairie and golden fields ecofuel providers… are among the multi centennial castles, monuments and mills now wind, solar and hydraulic universal converters.
Along this fairy trail, alternative energies (
“The emotional intelligence has become a recognized essential part of a global ‘balance’, in this virtual-reality.” Let’s see what we said some about 20 years ago, on related skills [
“Can we foresee the profile of the next generation of scientists and engineers? The people behind innovation are essential to establish the foundations of the
future successful businesses. In the chemical industry, the chemist, the physicist, the material scientist, the engineers are playing an important role in the creative process which is required to follow the pace of change. New organizational concepts have been proposed in order to schematize the industry adaptation to this ‘new’ global environment. We found that most of them require from the people a balance of skills which we propose to abbreviate with the acronym 4C, where the 4Cs represent: Connaissance, Creativity, Competence, Communication. ‘Pursuing with’, the bubble concept is one way of stimulating innovation. It is possible to combine enterprises or projects A, B, C in a way that the mentors, the promoters, the generators of the enterprise A have a chance to play another role in B or in C…”.
The number of current innovation styles, from open to close, disruptive, collaboratory®, from reverse to inclusive, nested and frugal, are more or less self-explanatory terminologies and further enlightenment can be found, e.g. in Lapray et al. [
More literature on artistic creation and more expressly musical art is dedicated to the innovation traits of musical production, rather say improvisation; Jazz is of an established relevance.
One may further cite Charkes Calamel proposed acronym “CRAC” [
of traits that innovation in the bigger data surrounding cannot miss.
Charles Calamel, (http://www.touteduc.fr/fr/archives), says: “Jazz is a model in that it leads the individual towards a self-direction in learning, a construction of oneself. Due to the conditions of play, the respect and transgression of codes and formats, jazz reverses the traditional pedagogic guidance system to set up a model of autonomy: it is not a question of receiving knowledge but rather of ‘Go find it’ ”.
Fred Hersch’s song title “Songs without Words” may further highlight the improvisation nature and emotional intelligence of creativity and innovation.
Emotional intelligence which may become more central to diversity innovative approach, to capture developmental potential, may not fit within the trend of bigger data and artificial intelligence interaction; although the later may be a source of improvisation.
In that domain D. Lapray and S. Rebouillat [
In
No need to be a professional in the advertisement arena or a malicious developer, of fake impression carried by photography angle shot selections, to realize that the above triangles configurations of
There is indeed an improvising dimension that may arise from bigger data analysis and visualization. Such as the representation on the left side may give a sharp and central dimension of the three first matters of Composit (es)-Fiber (s)-Materi (als)-(Polym (ers)), the central representation may imply a massive bulk dimension of the four, and the representation on the right may elude to a side lateral importance of the three first. Analogically the jazz player may improvise some mimics and positionings that will attract attention on some elements of his production and interactions.
The improvision dimension of innovation is certainly a way to liberate the creator away from core dimensions; those are prevalent and revealed in patent analysis wherein a language rarely changes as long as it is in the core corporate language and know hows. Laterals and boundaries are efficient add-ons in an inventive concept presentation.
In a nutshell, the parallel between innovation and art has been progressively
brought to the attention of the reader from a fairy tale landscape making innovative use of natural resources keeping “monuments in place”. Followed by the foresee, “4C”, dimension of the collaborative skills developed back in 1998 by Rebouillat. Extended to the Jazz science to education breadth and its self-learning integration value; associated with a high degree of intrinsic improvision. Closing the loop with the bigger data and artificial intelligence emotional limitations and potential for misleadingness that may deserve a longer propos in a review to come.
Instinctive and improvisional innovations are to be added on the list of [
Additional references on the above fields with selected technology domains are useful [
The present paper follows up on three reviews [
Smart or functional materials form a group of new and state of art materials now being developed that will have a significant influence on many of present-day technologies. Also called active materials, smart materials have the intrinsic and extrinsic capabilities, first, to respond to stimuli and environmental changes and to activate their functions according to these changes [
Most smart materials have reversible properties, reverting back to their original state after the stimulus is removed or changed. The cycle can then be repeated. Smart materials are also tailorable and tunable, which means they can be designed for specific, controlled property changes. To achieve a specific objective for a particular function or application, a new material has to satisfy specific qualifications related to technical and technological properties, economic criteria, raw material and production costs, supply expenses and availability, environmental characteristics and sustainable development criteria, implying reuse and recycling capacities.
If the functions of sensing and actuation are added to this list, the new material is considered a smart material [
Many other materials with added functions: have also been developed. They concern 1) sensor materials to detect certain signals, adjust sensitivity according to environmental changes, or restore degraded sensitivity, 2) catalytic materials to detect the progress of a reaction or distinguish the reaction of a product, 3) textile materials to detect a variety of signals from the human body and weather conditions so as to allow for greater comfort.
Smart composite materials: are also manufactured by combining two or more single smart materials in order to utilize synergistically the best properties of their individual constituents. Many of those composites are able to satisfy all of the above specific qualifications. Their advantages and adaptability to the design requirements mentioned above have led to a profusion of new products. There are two essential types of smart composite materials 1) completely tailored man-made composite materials which purpose is to improve or add strength or stiffness, 2) amalgamation of single/composite materials with fibre/reinforced polymers (FRPs) such as the ones used as reinforcement for concrete, steel or other construction materials. If the FRP is combined with fibre optic sensors, the resulting product will be an attractive and particularly cost effective smart composite.
A smart structure is a system that incorporates particular functions of sensing and actuation to perform smart actions in an ingenious way. It is composed of the following components:
・ Data Acquisition (tactile sensing) which collects the required raw data needed for an appropriate sensing and monitoring of the structure.
・ Data Transmission (sensory nerves) to forward the raw data to the local and/or central command and control units.
・ Command and Control Unit (brain) which manages and controls the whole system by analyzing the data, reaching the appropriate conclusion, and determining the actions required.
・ Data Instructions (motor nerves) which transmits the decisions and the associated instructions back to the structure.
・ Action Devices (muscles) which take action by triggering the controlling devices/units.
The Main areas of R&D involved in smart materials are:
・ For sensors and actuators: photo-sensitive materials, fibre optics, conductive polymers, thermally sensitive materials, shape memory materials, intelligent coating materials, chemical responsive materials, micro-capsules, micro- and nano-materials.
・ For signal transmission, processing and control: neural networks and control systems, cognition theory and systems.
・ For integrated processes and products: wearable electronics and photonics, adaptive and responsive structures, bio-mimics, tissue engineering, chemical/drug releasing.
In the last ten years, the field of smart materials has received much attention as a result of the development of new electro-active polymer (EAP) materials that exhibit a large displacement displacement response which changed the potential capability and paradigms of these materials. The main attractive characteristic of EAP is their operational similarity to biological muscles, particularly their resilience and ability to induce large actuation strains [
Today, the focus is on specialty products engineered for specific end-uses and on creative ways to market these products and the current generation of smart materials has many new dynamic features that enable them to adapt to the environment and make them the materials of the future, mainly, as this will be further outlined in this paper, in the domain of renewable biomass-materials.
The present paper follows upon three reviews [
value-added sustainable products endowed with physical, chemical and biological properties leading to particularly innovative applications.
This paper reviews recent works developed on those natural resources with the objectives of manufacturing smart materials. The biosourced products which will be considered are polysaccharides, including cellulose, hemicelluloses, chitin, chitosan, alginates, and their by-products (copolymers, blends and composites).
Polysaccharides are the most abundant materials that can be obtained from renewable and sustainable resources. They are biodegradable, carbon neutral with low environmental, health and safety risks and serve as structural material in the cell walls of plants. Some of them (e.g. cellulose and hemicelluloses) are used, for many years, as engineering material in many industrial processes such as pulp and papermaking and manufacture of synthetic textile fibres (e.g. organic and inorganic esters, alkyl, hydroxy alkyl and carboxyl alkyl ethers) which are important components in coatings, optical films, foodstuffs, pharmaceutics, cosmetics, additives in building materials, etc. [
Moreover, owing to polysaccharides properties, functionality, durability and uniformity, their use continue today in other domains (e.g. conversion into biofuels such as ethanol as an alternative fuel source and, more recently, in the design of processes using polysaccharide nanoparticles for the generation of novel polysaccharide-based biomaterials and composites [
On the other hand, it is noteworthy that chemical modifications of polysaccharides, “tailor-made” towards specific properties can also result in new materials, including smart materials. Indeed, owing to their unique and valuable functional properties, modified polysaccharides can confer smartness through somewhat unique mechanisms such as:
・ reversible, stimuli-responsive self-assembly (gelation),
・ biospecific interactions with enzymes and lectins (carbohydrate-binding proteins)
・ And interactions that confer nanoscale (e.g. fibril-forming) and hierarchical supramolecular assembly.
Nevertheless, today, the fundamental understanding of the molecular level interactions that confer smartness to polysaccharides remains relatively poor and one can predict that new experimental and theoretical tools will emerge to develop the necessary understanding of the structure-property-function relationships that will enable polysaccharide-smartness to be better understood and controlled, giving rise to the development of new and innovative applications. This would allow making polysaccharides materials of choice in the very promising areas of nanotechnology, foods, cosmetics and medicine (e.g. controlled drug release [
Cellulose is the major constituent of the plants cell walls [
Cellulose is a linear syndiotactic homopolymer composed of D-anhydroglucopyranose units which are linked by β-(1→4)-glycosidic bonds (
The high content of hydroxyl groups along the skeleton of cellulose, is the basis of an extended system made of intra- and inter-molecular hydrogen bonds allowing the formation of highly ordered, three-dimensional crystal structures, making cellulose a semi-rigid polymer made of elementary microfibrils with two structure regions: the crystalline region and the amorphous region [
Despite its high hydroxyl groups content, cellulose has limited functionalities and, to our knowledge, there are very few reviews on “smart” materials based on cellulose unless hydrogels which were referred to [
Type of cellulose | Fabricated material | Potential application | Reference |
---|---|---|---|
Nanofiber | Optically Transparent Nanofiber Paper | Flexible circuits | [ |
Nanofiber | Transparent nanocomposites | Electronics device industry | [ |
Nanofiber | Transparent cellulose-based nanocomposites | Solar panels | [ |
Nanocellulose | Antibiotics/Carbonated hydroxyapatite coatings on titanium | Implant materials | [ |
Nanocellulose | Scaffold materials | Cartilage tissue engineering | [ |
Bacterial nanocellulose (BNC) | Scaffold materials | Tissue engineering | [ |
Bacterial nanocellulose (BNC), | BNC membranes | Biomedical applications (drug delivery, cytotoxicity against cancer cells) | [ |
Carboxymethylcellulose (CMC) | Spherical CMC nanoparticles | Biomedical applications | [ |
CNFs photo-responsive nature can act as adaptive fillers in soft polymer matrices. CNCs properties such as low density, thermal stability, chemical resistance, high mechanical strength, biocompatibility and biodegradability allowed to consider them as functional materials in actuation systems and sensors for detecting pH, organic vapors, ions and humidity [
CNC based smart materials display intelligent behavior in response to environmental stimuli such as light, temperature, electrical input, pH, and magnetic force [
On the other hand, the properties of cellulose enable cellulose to be applied to the vast fields of smart electroactive polymers and hydrogels which can be fabricated through chemical modifications or physical incorporating/blending processes.
Chemical modifications of cellulose are realized using homogeneous or heterogeneous processes.
Homogeneous processes are mainly carried out by dissolution of cellulose derivatives (e.g. carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), and cellulose acetate (CA)) in suitable solvents (e.g. water or common organic solvents).
Heterogeneous processes are usually performed, after swelling in suitable solvents, on cellulose nanocrystals (CNCs), films/membranes, fibers, and cellulose particle suspensions.
In the processes of physical incorporating/blending, cellulose or cellulose derivatives act as matrices, fillers, or coatings/shells [
Recently, cellulose has been discovered as a smart material named cellulose-based electroactive paper (EAPap) [
Moreover, nanocellulose-based EAPap portrayed several superior characteristics such as ultra-lightweight, large bending deformation, low actuation voltage and low power consumption. These characteristics are very appealing for delicate biomimetic actuators and sensors, dynamic wings for flying articles, active sound-absorbing materials, adaptable speakers and smart shape control gadgets [
In addition, preparation of nano-cellulose-based smart material via chemical modification and physical incorporation or blending in various forms can affect
EAPap characteristic/quality | Potential application | Reference |
---|---|---|
Low electrical power consumption | Microwave-driven actuators | [ |
Biocompatible and hydrophilic properties | Biosensors | [ |
Microwave-driven innovations | Controlled actuators, Biomimetic robots | [ |
Reasonable quality | Vibration sensors | [ |
Acoustic characteristics | Acoustic applications | [ |
Stacked and unimorph EAPap actuator | Haptic applications | [ |
Piezoelectric paper | EAPap speakers | [ |
Ultra-lightweight and consumption of less energy ≥ response to electrical stimulatio | Microscale robotic insects, Tiny flying objects, Wireless power supplies | [ |
responsiveness to pH, temperature, light, mechanical forces, electricity, and magnetic field. The presence of porosity and refractive index variation has made EAPap a feature with extraordinary light-scattering effect (used as a transparent paper) for use in integrated transparent sensors and 3D microfluidic application.
However, even if there are already many potential applications for cellulose EAPap, it must be noted that, today, several important challenges remain and should be considered, for example in terms of reliability, material robustness and force improvement.
Gels are three-dimensional natural or synthetic polymer networks that can swell and absorb large amounts of solvents without dissolving, provided that chemical or physical crosslinks exist among the macromolecular chains.
Hydrogels are, mainly, structures formed from biopolymers and/or polyelectrolytes, and contain large amounts of trapped water. They can be divided into chemical gels and physical gels. Chemical gels are formed by covalent bonds while physical gels are formed by molecular self-assembly through ionic or hydrogen bonds [
Responsive hydrogels can undergo a swelling transition in response to environmental stimuli, such as the changes in temperature, light, pH, etc. Because of this unique feature, responsive hydrogels have received an extensive attention in the fields of drug delivery [
Hydrogels | Application | Reference |
---|---|---|
Polymer blends of natural and/or synthetic polymers | Drug delivery | [ |
Supramolecular hydrogels | Drug delivery | [ |
Chitosan and Polyethylenimin | Tissue engineering | [ |
Natural polymers (collagene, hyaluronic acid alginate, chitosan) and synthetic polymers (PEO, PEG and corresponding block copolymers with poly (lactic acid) | Tissue engineering | [ |
Methacrylate/acrylic acid (AA) copolymers | Inverse opal pH sensors | [ |
Poly(acrylic acid)/poly(vinyl alcohol) | Piezoresistive pH sensors | [ |
GM3 material (terpolymer, based on high-purity glycerol methacrylate) from Contamac, UK (49.3% Water content) | contact lenses | [ |
Nanofilm-encapsulated silicone-hydrogel | contact lenses | [ |
Ni2+-poly (2-acetamidoacrylic acid) hydrogel | Purification of histidine-tagged green fluorescence proteins | [ |
change can control the loading/unloading of reactants in the hydrogel network, which, in turn, changes the reactivity.
There are plenty of methods for preparing hydrogels. The mixing of anionic and cationic polymers solutions is widely used for preparing reversible hydrogels. The final properties of the 3D network of physical hydrogel should depend on several factors such as the anionic/cationic charge ratio, the pH and the existence, or not, of stirring and the respective speed during the preparation, as well as several other parameters.
After these basic definitions and examples, the following paragraphs aim at highlighting some of the most recent developments in cellulose-based hydrogels materials, including pure cellulose, cellulose composite and cellulose hybrid hydrogels.
Two routes have been thoroughly developed for their preparation:
・ Direct preparation from native cellulose
Due to its highly extended hydrogen bonded structure, native cellulose is very difficult to be dissolved in common solvents. Recently, new solvents have been developed to dissolve cellulose providing great opportunities for the preparation of cellulose hydrogels. The main solvents used for those hydrogel preparations are: LiCl/dimethylacetamide (DMAc), N-methylmorpholine-N-oxide (NMMO), Ionic liquids (ILs), Alkali/urea (or thiourea) aqueous systems.
・ Cellulose derivatives-based hydrogels
Cellulose derivatives such as MC, HPC, HPMC and CMC have been used to fabricate cellulose-based hydrogels through physical and chemical cross-linking. Physical cross-linked gels are formed by ionic bondings, hydrogen bondings, or associative polymer-polymer interactions. Chemical cross-linked hydrogels are prepared by cross-linking two or more polymer chains with a functionalized cross-linker.
With the development of cellulose derivatives, mainly cellulose ethers, some stimuli-responsive hydrogels have been developed leading to temperature sensitive hydrogels and pH sensitive hydrogels from MC, HPC, HPMC and CMC.
Cellulose-based hydrogels have many favorable properties such as hydrophilicity, biodegradability, biocompatibility, transparency, low cost, and non-toxicity. Therefore, cellulose-based hydrogels have many applications (
Cellulose (or its derivatives) has been blended with both natural biodegradable polymers and synthetic polymers. Combining the different properties of cellulose and other polymers has given rise to novel hydrogel smart materials with specific applications. Various composite hydrogels were designed in wide size from macroscopic materials such as membranes, fibers, and beads to microscopic materials such as microgels, and nanogels (
Cellulose-based hydrogel | Application | Reference |
---|---|---|
Si-HPMC | Tissue engineering | [ |
Na-CMC and cellulose | Controllable delivery systems | [ |
Cellulose acetate and phospholipids | Blood purification | [ |
Crosslinked (HEC) and (CMC) | Sensors and actuators | [ |
CMC/Acrylamide | Super absorbents for agriculture and horticulture | [ |
Poly[(N-tert-butylacrylamide)-co-acrylamide]/HPC | Swelling temperature-sensitive agents | [ |
Cellulose/chitin beads | Water purification | [ |
Regenerated cellulose beads modified with silane | Chromatographic supports | [ |
Cellulose-polymers composite hydrogels | Application | Reference |
---|---|---|
CMC/Chitosan | Cells immobilization | [ |
Starch/Cellulose-based polymers (sodium alginate, HPMC, NaCMC) | Thermal behaviour | [ |
CMC/Starch | Textile sizing and floculation agents | [ |
Na alginate/gelatin, and Na alginate/NaCMC blend beads | Release of carbaryl | [ |
Alginate/MC | pH-sensitive hydrogels | [ |
Hyaluronic acid/HEC; Hyaluronic acid/NaCMC | Use in prevention of postsurgical soft tissue adhesion | [ |
In recent years, polymeric-inorganic hybrid materials have attracted increasing attention due to potential applications in electric, optical, magnetic, and biological fields. Introduction of inorganics into cellulose hydrogel networks is an effective way to develop materials with high functionality. Indeed, cellulose hydrogels have been used as matrices to incorporate inorganic nanoparticles for preparing cellulose-inorganic hybrid hydrogels [
On the other hand, even if cellulose is known to be non-bioresorbable, it seems possible to functionalize cellulose-based hydrogels with bioactive and biodegradable extracellular matrix domains. This suggests that, in the near future, such hybrid hydrogels might constitute ideal platforms for the design of scaffolding biomaterials that could be used in the fields of tissue engineering and regenerative medicine.
Hemicelluloses, as natural polysaccharides, are categorized as the second most abundant components of the plants after cellulose and constitute about 20% - 30% (w/w) of the total weight of the lignocellulosic biomass [
It is worth noting that the pendant hydroxyl groups of the polysaccharide backbone offer a number of possibilities for the chemical modification of hemicelluloses and for the preparation of materials with new profiles that can increase the utility of these biopolymers. Several methods are applied to extract hemicelluloses from biomass (
Increasing attention has been concentrated on the development and application of hemicellulosic products because of their numerous inherent advantages, including non-toxicity, biocompatibility, biodegradability, and anti-cancer effect [
Raw material | Extraction method | Advantages/Disadvantages | Reference |
---|---|---|---|
Softwood | Single- and two-stage diluted-sulfuric acid pretreatment | Degraded dissolved sugars | [ |
Corn stalks | Autohydrolysis and alkaline extraction processes | Hemicellulose of high purity | [ |
Biomass | Hot water treatment and water/acetone extraction | Cleavage of hemicellulose acetate groups | [ |
Spruce | Microwave oven or steam treatment | Successful extracion of hemicellulosic oligosaccharides | [ |
Kraft pulp | Extraction with ionic liquid/cosolvent systems | Hemicellulose with high purity | [ |
Firstly, hemicelluloses have been used as fermentation feedstocks in production of ethanol, butanol, and xylitol [
Secondly, due to their large content of hydroxyl groups, hemicelluloses can be modified by both chemical reactions and physical interactions. The main chemical reactions are etherification, esterification and chemical crosslinking which allow preparing many materials such as packing films, oxygen barrier [
Nevertheless, most of the materials made with hemicelluloses are smart hydrogels. Many kinds of hemicelluloses from different of plants such as birch wood, aspen wood, spruce, bamboo, straw etc., have been used for the preparation of such materials. However, these hydrogels display weak thermostability, brittle properties and weak mechanical properties which restrict their application in material field. Nevertheless, this can be partially overcome through blending hemicelluloses with compatible products, as shown in
Chitin is the most widespread aminopolysaccharide and is the second natural polysaccharide after cellulose that can be obtained as a cheap renewable biopolymer from marine sources. As shown in
Due to its intermolecular hydrogen bonds, chitin is insoluble in water and in organic solvents, which, despite its enormous availability, limits its use. Nevertheless, several attempts have been reported to solve this problem owing to chemical modifications which allowed giving rise to derivatives such as chitosan or carboxymethyl chitin. Indeed, most of those derivatives are soluble in aqueous media and can be used as fibers, hydrogels, beads, sponges, and membranes [
The main applications of chitin and chitosan materials have been thoroughly reviewed by some researchers [
Nevertheless, chitin-based smart materials or composites have also been created. Among those materials, shape memory materials containing polyurethanes molecules, are gaining more attention. Indeed, polyurethanes present good shape memory effect at room temperature. But polyurethanes cannot bear repeated changes in the shape memory, and retention will decrease by increasing the number of cycles of shape memory. Consequently, chitin-based polyurethane shape memory materials have been developed to overcome those problems [
Chitosan is a linear polysaccharide composed by two kinds of randomly distributed β(1→4)-linked structural units: 2-amino-2-deoxy-d-glucopyranose (D-glucosamine) and 2-acetamid-2-deoxy-d-glucopyranose (N-acetyl-D- glucosamine). It is obtained by extensive deacetylation of chitin.
Considering its low toxicity, biocompatibility, biodegradability and indirect abundance in nature, chitosan has attracted much research interest and has found potential applications in pharmaceutical, paper, textiles, cosmetic, and food industries, as well as in agriculture and medicine [
Moreover, chitosan is known for its absorption of exudes, anti-fungal, anti-microbial, anti-viral and wound-healing properties and is useful as a wound management aid to reduce scar tissue.
There is an increased interest in preparing chitosan and various macromolecules blends for mitigating undesirable properties and a rapidly growing list of
Raw material | Hemicellulose | Hydrogel synthesis | Hydrogel properties and potential applications | Reference |
---|---|---|---|---|
Bambo | Xylan | Grafting with AA + Crosslinking | High swelling, sensitive to pH | [ |
Spruce pulp | AcGGM | Grafting with MA + Crosslinking | Drug release | [ |
Crude spruce hydrolysate | AcGGM | Free radical graft copolymerization and cross-linking of poly(amidoamine)/AcGGM | High absorption capacity for heavy metal ions | [ |
Dextran | AcGGM | In situ Michael-type addition using vinyl sulfone | Thermosensitive injectable hydrogels | [ |
Birch wood | Xylan | Introduction of allyl groups + reaction with thioacetic acid, + free thiol-thiol oxidative coupling | 3D hydrogel scaffolds and cross-linked foams | [ |
Crude spruce hydrolysate | AcGGM | Direct incorporation of hemicellulose into a semi-IPN matrix obtained by crosslinking polymerization of MA-CMC with AA | Appreciable mechanical performance and high swelling ratio | [ |
Crude spruce hydrolysate | AcGGM | Synthesis of Hemicellulose full IPN by free-radical polymerization and a thiol-ene click reaction | Fast swelling rates and highly porous structure | [ |
Spruce TMP | AcGGM | Functionalization of carboxylated AcGGM with GMA and covalent immobilization of conductive AT onto GMA. | Electrically conductive hydrogels with high and controllable swelling | [ |
Spruce TMP | AcGGM | Cross-linking of AcGGM in a One-pot reaction with E in the presence of AP | Conductivity, swelling and mechanical properties for biomedical applications | [ |
Spruce TMP | AcGGM | In situ fabrication of microgels by chemical cross-linking during spray drying | Conductivity, mechanical properties, biomedical applications | [ |
Eucalyptus (Acid acetic pulping) | Xylan and glucomannan | Grafting maleic MA to hemicellulose and UV photo-crosslinking with NIPAAm | Temperature responsive | [ |
Birchwood | Xylan with glucuronic acid functionalities | Network formation by complexation between glucuronic acid of xylan and amino groups of chitosan | Porous structure, sensitive to pH. | [ |
Bamboo | Xylan with glucuronic acid functionalities | Use of Freeze-thaw process to obtain reinforced hybrid hydrogel of Hemicelluloses/PVA/Chitin Nanowhiskers | Improved mechanical and thermal properties (applications in tissue engineering) | [ |
Beech | Xylan | Mixing of Xylan, kappa-carrageenan and oat spelt | Improvement of gelling and melting temperatures of Kappa-Carrageenan hydrogels | [ |
Pinewood, Switchgras and Coastal bermuda grass | Various hemicelluloses | Grafting with DTPA and cross-linking with chitosan | Biosorbent for Water Desalination and Heavy Metal Removal | [ |
Abreviations: AA: Acrylic acid; MA: Maleic anhydride; AcGGM: O acetyl-galactoglucomannan; AP: Aniline pentamer; AT: Aniline tetramer; DTPA: Diethylene triamime pentacetic acid; E: Epichlorohydrine; GMA: Glycidyl methacrylate; IPN: interpenetrating polymer network; MA-CMC: Methacrylated Carboxymethylcellulose; NIPAAm: N-isopropylacrylamide; TMP: Thermo-mechanical pulping.
biomaterial applications. Examples are chitosan blends with cellulose, cellulose acetate, xanthan, gelatin, silk, polyamide, poly (acrylic acid), poly (vinyl alcohol), polyamide, gellan, collagen, glycine, poly (N-vinyl pyrrolidone).
On the other hand, chitosan structure can be modified through its amino group and the hydroxyl groups. These chemical modifications improve chitosan mechanical properties and solubility or bring new functional properties and promising applications. In this sense, a wide variety of chitosan thermosensitive materials has been generated, like nanostructures, scaffolds, membranes, cryogels and paramagnetic beads, to cite some of them [
Moreover, because of the polyelectrolyte nature of chitosan, several chitosan-based materials are also sensitive to changes of pH, ionic strength etc, and hence have an advanced interest due to specific technological potential applications as sensors, actuators, controllable membrane for separations and modulators of drugs delivery for use in medicine, biotechnology and other fields.
On the other hand, chitosan can also be induced to undergo reversible sol-gel transition forming hydrogels or films by changing chemical or pH gradients [
Alginate is a natural polysaccharide that has two main sources: bacteria and seaweed (brown algae). It is composed of mannuronic acid residues (M-blocks), guluronic acid residues (G-blocks) and alternating M and G residues (MG-blocks). This chemical composition shows that alginate is a polymer with a polyelectrolyte nature.
Alginate, exhibits excellent biocompatibility and biodegradability and has many different industrial applications linked to 1) its ability to absorb water 2) its gelling, viscosifying and stabilizing properties. Alginate is used in several industrial fields such as textiles, food, pharmaceuticals, cosmetics, waste water treatment and paper industry together with biomedical supplies.
Alginate is readily processable for applicable three-dimensional scaffolding
Functionalization | Synthesis | Characteristic | Application | Reference |
---|---|---|---|---|
Cross-linking | With glutaraldehyde and sulfosuccinic acid | Protonic conductivity | Membrans for Fuel cells | [ |
Cross-linking | With di- and tri-carboxylic acids | nano-hydrogels | Drug release | [ |
Graft copolymerization | Copolymerization of metacrylic acid with chitosan in the presence of APS | Improved water solubility | Antibacterial activity | [ |
Graft copolymerization | Copolymerization of maleic acid with (CMCTS) and (HPCTS) | Improved scavenging ability | Antioxidant activity | [ |
Graft copolymerization | Copolymerization of aniline with chitosan | Protonic conductivity | Conductive films and fibers | [ |
Carboxymethylation | Monochloroaetic acid | Solubility depends on pH | Antimicrobial activity, affinity with metal ions, Controlled release of drugs | [ |
Phosphorylation | Heating chitosan with orthophosphoric acid in DMF or with phosphorous pentoxide in methanesulphonic acid | Solubility in water under neutral conditions | Bactericidal, biocompatible, bioabsorbable, osteoinductive and metal chelating properties | [ |
Esterification | Reaction of acyl chlorides with chitosan (synthesis of N,O-Acyl chitosan derivatives) | Reaction mainly occurred on the OH group and not on the NH2 group | Highly improved antifungal activity | [ |
Etherification | Synthesis of N-phthaloyl chitosan. (MPEG) iodide | Soluble in water and aqueous solutions of wide pH range | Extremely low reduced viscosity | [ |
Self-rearrangement of polymer networks | chitosan/chondroitin sulfate formed by polyelectrolyte complexation | Crystallinity, higher thermal stability, porosity, and water uptake capacity | pH sensitive material which can be tailored to several specific applications | [ |
BC/Ch composite preparation | Immersing wet BC pellicle in chitosan solution followed by freeze-drying | porous network structure and large aspect surface | Wound dressing or tissue-engineering scaffolds | [ |
Reversible blending | Mixing of chitosan/PHEMA | Swollen structure | Electrically sensitive behavior | [ |
Electrospun chitosan fibers | Electro-wet-spinning (submicron scale) | Fast and reversible electroactuation | Application in artificial muscles | [ |
Blending of chitosan and Cellulose | Preparation of chitosan/cellulose blend beads | Blend beads with rough and folded surface morphology | Odor treatment and metal ions adsorption | [ |
Casting of a TFA solution of chitosan and cellulose | Large bending displacement under low voltage | Blended dry and durable actuator | [ | |
Blending of chitosan with PCL | Chitosan and PCL homogeneously dissolved in acetic acid/water and processed into uniform membranes | Blends with chemical bonds | biological and anti-bacterial properties | [ |
Preparation of poly(AA-co AM)/(O-CMC) interpenetrating polymer network | Synthesis of a semi-IPN by AA and AM copolymerization of in the presence of O-CMCthen synthesis of a full-IPN through cross-linking | Superporous hydrogel | Mucosal drug delivery system, especially for peroral delivery of peptide and protein drugs | [ |
Abreviations: APS: Ammonium persulfate; BC: Bacterial cellulose; Ch: Chitosan; CMCTS: chitosan-carboxymethyl chitosan; DMF: N,N-dimethylformamide; HPCTS: hydroxypropyl chitosan; IPN: Interpenetrated Network; MPEG: Poly (ethylene glycol) monomethyl ether; NMMO: N-Methylmorpholine-N-oxide; PCL: poly (ε-caprolactone); PHEMA: poly (hydroxyethyl methacrylate); TFA: Trifluoroacetic acid; AA: Acrylic acid; AM: Acrylamid; OCMC: O-carboxymethyl chitosan.
materials such as hydrogels, microspheres, microcapsules, sponges, foams and fibers that provide responses to internal/external stimuli.
Alginate-based biomaterials can be utilized as drug delivery systems and cell carriers for tissue engineering, control release, matrix for living cells, immobilization of microorganisms [
As cellulose, hemicelluloses and chitosan, alginate can be easily modified via chemical reactions and physical interactions, to obtain derivatives with various structures, properties, functions and applications. Various techniques such as 1) oxidation, sulfation, copolymerization and coupling of cyclodextrin units, 2) esterification, use of Ugi reaction and amidation, are employed for chemical modification of the hydroxyl groups and carboxyl groups of alginate, respectively [
Moreover, owing to its structure and properties, alginate can be achieved through 1) combination with other biomaterials, 2) immobilization of specific ligands such as peptide and sugar molecules, and 3) physical or chemical crosslinking (
This paper reviews the recent progress developed to produce and characterize smart materials using the most abundant products of the biomass, i.e. polysaccharides which include cellulose, hemicelluloses, chitin, chitosan, and alginates and their by-products. Owing to their low density, thermal stability, chemical resistance, high mechanical strength, biocompatibility, biodegradability, functionality, durability and uniformity, those products are materials of choice for the preparation of smart products that can be used in the very promising areas of nanotechnology, foods, cosmetics and medicine (mainly controlled drug release and regenerative medicine) and so, opening up major commercial markets in the context of green chemistry.
The resulting smart materials are generally prepared through direct utilization and/or after chemical or physical modifications of the polysaccharides.
Cellulose and its different physical structures (particularly cellulose nanofibers and nanoparticles, i.e. nanocelluloses) can be transformed into high value-added smart blends and composites with applications in important industrial areas such as those of flexible circuits, solar panels, implant materials, cartilage tissue engineering, drug delivery, etc.
Moreover, owing to its unique cristalline structure and its piezoelectric behaviour, cellulose has also the characteristics of an electroactive polymer, with potential applications in biomimetic sensors/actuators and electromechanical biosystems.
Together with hemicelluloses, chitosans and alginates, cellulose can give rise
Functionalization | Experimental strategy | Material characteristics | Application | Reference |
---|---|---|---|---|
Oxidation | Controlled reactions on-OH groups of C-2 and C-3 with sodium periodate | Cleavage of carbon-carbon bond of cis-diol groups and formation of acetal groups | Powerful material for tissue engineering, Drug-controlled delivery systems | [ |
Sulfation | Reaction of sodium alginate with a sulfating agent (N (SO3Na)3) | Sodium alginate sulfate with DS of 1.87 | Anticoagulant activity | [ |
Reaction with ClSO3H in formamide | Alginate sulfate and its quaterized derivatives | Anticoagulant activity and potential application as anti-HIV | [ | |
Reductive-amination of oxidized alginate | Synthesis of APSs with a linear alkyl group (C8, C12, C16) | Low interfacial tension value | Surfactant activity and adsorption of heavy metal | [ |
Syntheseis of (HM-alginate) via reaction of sodium alginate with dodecyl glycidyl ether | Zeta-potential of HM-alginate higher than that of sodium alginate. Very low viscosity | Ecology-safe material to encapsulate lipophilic substances | [ | |
Copolymerization | Synthesis of a copolymer of sodium acrylate with sodium alginate | Water absorbency of the hydrogel ≥ 85 times its own mass | Superabsorbent resistant to salinesolution | [ |
Microwave-initiated synthesis of SA-g-PAM | MW and Intrinsic viscosity greater than that of SAG. | Polymeric flocculant | [ | |
Graft copolymerization of VSA onto alginate in the presence of (PDP)/thiourea | Thermally more stable than alginate | Metal ion sorption, Flocculant, Resistant to biodegradability | [ | |
Esterification | Synthesis of derivatives of sodium alginate, by chemical binding of long alkyl chains onto alginate backbone via ester functions | Increasing of the hydrophobic nature of native alginate | Protein carrier with High encapsulation yields and important release properties | [ |
Esterification of alginate by butanol | Very stable material with gelling and non-toxic properties | Encapsulation of both hydrophilic and hydrophobic molecules | [ | |
Ugi reaction | Sodium alginate dissolved in water + formaldehyde, octylamine and cyclohexyl isocyanide | Self-aggregated micelles with high thermal stability and good amphiphilic functionality | High potential in pharmacology and tissue engineering | [ |
Crosslinking Preparation of poly (AA-co AM)/(SA) interpenetrating polymer network | 1) Synthesis of a semi-IPN by copolymerization 2) Crosslinking with Bis | IPN with a superporous structure, good mechanical properties, pH sensitivity | Potential candidate in the field of Drug delivery system | [ |
Preparation of poly (AA)/(SA) interpenetrating polymer network | 1) Synthesis of SA beads 2) Synthesis of hydrogels hybrids by polymerization of AA and crosslinking | Strong and elastic superporous hydrogel, high network density, good mechanical properties | Various pharmaceutical, biomedical and industrial applications | [ |
Abreviations: Bis: N,N’-methylenebisacrylamide; DS: degree of substitution; APSs: alginate-derived polymeric surfactants; HM-alginate: hydrophobic modified alginate; MW: Weight average molecular weigth; SA: sodium alginate; SA-g-PAM: sodium alginate grafted polyacrylamide; VSA: vinyl sulfonic acid; PDP: potassium peroxydiphosphate.
to several types of stimuli-responsive hydrogels (e.g. temperature responsive, pH-sensitive, protonic conductor, etc.) able to be used in numerous applications such as tissue engineering, absorption of heavy metal ions, odor treatments, liquid and gas absorbtion, polymeric floculation, energy storage etc.
All those investigations clearly show the great potential of polysaccharides for the production of cheap, disposable and environmentally friendly devices. However, as shown in different sections of the present review, still more comprehensive studies are required to broaden the fundamental understanding of molecular level interactions that confer smartness to polysaccharides. This would allow manufacturing new materials with new applications, able to bring more technological impacts to markets.
Regarding innovation and bigger data: in a nutshell, the parallel between innovation and art has been progressively brought to the attention of the reader from a fairy tale landscape making innovative use of natural resources keeping “monuments in place”. Followed by the foreseeing, “4C”, dimension of the collaborative skills developed back in 1998 by Rebouillat [
Finally, Smart Materials are along with Innovation attributes and Artificial Intelligence among the most used “buzz” words in all media. Central to their practical occurrence, many talents are to be gathered within new contextual data influxes. Has this, in the last 20 years, changed some of the essential fundamental dimensions and the required skills of the actors such as providers, users, insiders, etc.? This is a preliminary focus and prelude of this review which shall not be ignored.
The era of smart materials may deserve an artistic warning-illustration to complete the picture of its tremendous potential with some level of disruptive improvisation in
Benoit Steffenino: DuPont™ Fellow technologist. His pictorial skills bring concepts to an entertaining journey.
The authors declare no conflicts of interest regarding the publication of this paper.
Serge Rebouillat [Phonetically: Rebooya], Dr. Ing., Docteur ès Sciences, Certified Prof., Ind. Energetic, Chem/Bio Eng., Rheology, IP: Mediation/Innovation & Strategy/Management/Valuation.
Fernand Pla, Dr. Ing., Dr-es-Sciences Physiques, full Professor at the University of Lorraine (Nancy, France), Head of a research group working in Polymer Reaction Engineering.
This article is primarily for educational purposes. Selected cases are strictly illustrative. Neither the authors nor the illustrator assume any liability for any errors or oversights, for how this article or its contents are utilized or interpreted or for any consequences resulting directly or indirectly from the usage of it.
This information is for general knowledge. For critical applications, requirements should be checked with the suppliers. For additional guidance, legal or any other, seek advice from the appropriate qualified professionals; this study can by no means substitute for legal, technical and managerial expert advice.
The opinions expressed by the writers in this article do not necessarily represent the viewpoints of the company which one of the authors is employed by.
Rebouillat, S. and Pla, F. (2019) A Review: On Smart Materials Based on Some Polysaccharides; within the Contextual Bigger Data, Insiders, “Improvisation” and Said Artificial Intelligence Trends. Journal of Biomaterials and Nanobiotechnology, 10, 41-77. https://doi.org/10.4236/jbnb.2019.102004