A Review of Natural Polysaccharides: Sources, Characteristics, Properties, Food, and Pharmaceutical Applications

Natural polysaccharides, which are described in this study, are some of the most extensively used biopolymers in food, pharmaceutical, and medical applications, because they are renewable and have a high level of biocompatibility and biodegradability. The fundamental understanding required to properly exploit polysaccharides potential in the biocomposite, nanoconjugate, and pharmaceutical industries depends on detailed research of these molecules. Polysaccharides are preferred over other polymers because of their biocompatibility, bioactivity, homogeneity, and bioadhesive properties. Natural polysaccharides have also been discovered to have excellent rheological and biomucoadhesive properties, which may be used to design and create a variety of useful and cost-effective drug delivery systems. Polysaccharide-based composites derived from natural sources have been widely exploited due to their multifunctional properties, particularly in drug delivery systems and biomedical applications. These materials have achieved global attention and are in great demand because to their biochemical properties, which mimic both human and animal cells. Although synthetic polymers account for a substantial amount of organic chemistry, natural polymers play a vital role in a range of industries, including biomedical, pharmaceutical, and construction. As a consequence, the current study will provide information on natural polymers, their biological uses, and food and pharmaceutical applications.

Grafting Polymerization of Long-Chain Hydrophobic Acrylic Monomer onto Lignin and Its Application in Poly(Lactic Acid)-Based Wholly Green UV Barrier Composite Films

The development of low-cost and high-performance bio-based composites derived from forestry waste lignin and polylactic acid has emerged as a topic of central attention. However, the weak compatibility between lignin and polylactic acid often resulted in high brittleness of the composites. Graft copolymerization is not only the most effective way to modify lignin but also can significantly improve the compatibility of lignin and polylactic acid. In this study, bio-based monomer lauryl methacrylate was grafted onto lignin by feasible radical polymerization to prepare lignin graft copolymers with excellent thermal stability and hydrophobicity, which are expected to improve the compatibility with polylactic acid. Wholly bio-based composites were prepared by compounding this graft copolymer with polylactic acid. The results showed that the crystallization ability of the composite was improved, and the highest crystallinity was increased from 6.42% to 17.46%. With addition of LG-g-PLMA lower than 9%, the thermal stability of the composites was slightly improved. At 5% copolymer addition, the elongation at break and tensile toughness of the composites increased by 42% and 36%, respectively. Observation of the frozen fracture surface of the composite by SEM found that wire drawing and ductile deformation appeared when a small amount of LG-g-PLMA was added. The thus prepared composites also showed excellent UV barrier properties. This approach provides a new idea for the high-value application of lignin.

Recent advances in synthesis of polymers based on palm oil and its fatty acids

Palm oil is a versatile bio-renewable resource for consumer products, oleochemicals, and biofuels. The utilization of palm oil in polymer production as a bio-based polymer is considered a promising alternative to conventional petrochemical-based polymers due to its non-toxicity, biodegradability, and vast obtainability. Triglycerides and fatty acids in palm oil and their derivatives can be utilized as bio-based monomers for synthesizing polymers. This review summarizes the recent advancement in using palm oil and its fatty acids for polymer synthesis and their applications. Moreover, this review will overview the most commonly used synthesis pathways for producing palm oil-based polymers. Therefore, this review can be used as a reference for designing a new approach to synthesizing palm oil-based polymers with desired properties.

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

Access to a wide range of plastic materials has been rationalized by the increased demand from growing populations and the development of high-throughput production systems. Plastic materials at low costs with reliable properties have been utilized in many everyday products. Multibillion-dollar companies are established around these plastic materials, and each polymer takes years to optimize, secure intellectual property, comply with the regulatory bodies such as the Registration, Evaluation, Authorisation and Restriction of Chemicals and the Environmental Protection Agency and develop consumer confidence. Therefore, developing a fully sustainable new plastic material with even a slightly different chemical structure is a costly and long process. Hence, the production of the common plastic materials with exactly the same chemical structures that does not require any new registration processes better reflects the reality of how to address the critical future of sustainable plastics. In this review, we have highlighted the very recent examples on the synthesis of common monomers using chemicals from sustainable feedstocks that can be used as a like-for-like substitute to prepare conventional petrochemical-free thermoplastics.

Synthesis and Evaluation of Thermoresponsive Renewable Lipid-Based Block Copolymers for Drug Delivery

Polymeric micelle forming from self-assembly of amphiphilic macromolecules is one of the most potent drug delivery systems. Fatty acids, naturally occurring hydrophobic lipid components, can be considered as potential candidates for the fabrication of block copolymer micelles. However, examples of synthesis of responsive block copolymers using renewable fatty acids are scarce. Herein, we report the synthesis, characterization and testing of block copolymer micelles composed of a renewable fatty-acid-based hydrophobic block and thermoresponsive hydrophilic block for controlled drug delivery. The block copolymers of functionalized fatty acid and poly(N-isopropylacrylamide) (PNIPAM) were prepared via consecutive microwave-assisted reversible addition fragmentation chain transfer (RAFT) polymerization. The block copolymers with variable hydrophobic block length self-assembled in aqueous media and formed spherical nanoparticles of ~30 nm with low critical micelle concentration (CMC). To demonstrate the proof-of-concept, carbamazepine (CBZ) was used as a hydrophobic model drug to evaluate the performance of these micelles as nanocarriers. The in vitro drug release tests were carried out below (25 °C) and above (37 °C) the lower critical solution temperature (LCST) of the block copolymer. The drug release showed obvious temperature-triggered response and an accelerated drug release at 37 °C.

Synthesization and Characterization of Lignin-graft-Poly (Lauryl Methacrylate) via ARGET ATRP

Lignin as an abundant biological macromolecule isolated from the plant cell wall, and it cannot be efficiently utilized until suitable modifications to its structures were made. Therefore, we proposed a strategy to prepare an all biomass-based Lignin-graft-poly(Lauryl methacrylate, LMA) by grafting LMA monomers on the organosolv lignin through ARGET ATRP. The results of FT-IR and ¹H NMR analysis demonstrated that PLMA molecular chains were successfully grafted on the lignin. Lignin improved copolymer's thermal stability and had a negligible effect on crystallization of PLMA molecular chains, according to our findings in the test of TGA and DSC. The rheological properties of the copolymer were found depending on the length of molecular chains of copolymer and lignin inside it. Both height and phase images of AFM suggest that lignin constituted a nanoscale aciculas and embedded in the microscale spheral dot composed by grafted PLMA molecular chains. Furthermore, the integrated consideration of results of all characterizations suggests a relative independent micro-component, which was composed by central lignin and peripheral PLMA, aggregates with each other to build the OL-g-PLMA copolymers. It hopes that the copolymer will be used as an additive for improving mechanical performance and UV blocking of other biopolymers.

Fatty Acid-Based Polymeric Micelles to Ameliorate Amyloidogenic Disorders

To develop anti-amyloidogenic inhibitors for ameliorating the treatment of diabetes, herein, we have synthesized amphiphilic block copolymers with side-chain fatty acid (FA) moieties via reversible addition fragmentation chain-transfer (RAFT) polymerization....

Plant oil-based polymers

Polymer materials derived from natural resources have gained increasing attention in recent years because of the uncertainties concerning petroleum supply and prices in the future as well as their environmental pollution problems. As one of the most abundant renewable resources, plant oils are suitable starting materials for polymers because of their low cost, the rich chemistry that their triglyceride structure provides, and their potential biodegradability. This chapter covers the structure, modification of triglycerides and their derivatives as well as synthesis of polymers therefrom. The remarkable advances during the last two decades in organic synthesis using plant oils and the basic oleochemicals derived from them are selectively reported and updated. Various methods, such as condensation, radical/cationic polymerization, metathesis procedure, and living polymerization, have also been applied in constructing oil-based polymers. Based on the advance of these changes, traditional polymers such as polyamides, polyesters, and epoxy resins have been renewed. Partial oil-based polymers have already been applied in some industrial areas and recent developments in this field offer promising new opportunities.

RAFT polymerization mediated core-shell supramolecular assembly of PEGMA-co-stearic acid block co-polymer for efficient anticancer drug delivery

In this work, core-shell supramolecular assembly polymeric nano-architectures containing hydrophilic and hydrophobic segments were synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Herein, polyethylene glycol methyl ether methacrylate (PEGMA), and stearic acid were used to synthesize the poly(PEGMA) homopolymer and stearyl ethyl methacrylate (SEMA), respectively. Then, PEGMA and SEMA were polymerized through controlled RAFT polymerization to obtain the final diblock copolymer, poly(PEGMA-co-SEMA) (BCP). Model anticancer drug, doxorubicin (DOX) was loaded on BCPs. Interestingly, efficient DOX release was observed at acidic pH, similar to the cancerous environment pH level. Significant cellular uptake of DOX loaded BCP50 (BCP50-DOX) was observed in MDA-MB-231 triple negative breast cancer cells and resulted in a 35 fold increase in anticancer activity against MDA MB-231 cells compared to free DOX. Scanning electron microscopy (SEM) imaging confirmed the apoptosis mediated cellular death. These core-shell supramolecular assembly polymeric nano-architectures may be an efficient anti-cancer drug delivery system in the future.

Fabrication of a Self-Healing, 3D Printable, and Reprocessable Biobased Elastomer

A novel self-healable, fully reprocessable, and inkjet three-dimensional (3D) printable partially biobased elastomer is reported in this work. A long-chain unsaturated diacrylate monomer was first synthesized from canola oil and then cross-linked with a partially oxidized silicon-based copolymer containing free thiol groups and disulfide bonds. The elastomer is fabricated through inkjet 3D printing utilizing the photoinitiated thiol-ene click chemistry and reprocessed by compression molding exploiting the dynamic nature of disulfide bond. Self-healing is enabled by phosphine-catalyzed disulfide metathesis. The elastomer displayed a tensile strength of ∼52 kPa, a breaking strain of ∼24, and ∼86% healing efficiency at 80 °C temperature after 8 h. Moreover, the elastomer showed excellent thermal stability, and the highest thermal degradation temperature was recorded to be ∼524 °C. After reprocessing through compression molding, the elastomer fully recovered its mechanical and thermal properties. These properties of the elastomer yield an ecofriendly alternative of fossil fuel-based elastomers that can find broad applications in soft robotics, flexible wearable devices, strain sensors, health care, and next-generation energy-harvesting and -storage devices.

Progress Toward Sustainable Reversible Deactivation Radical Polymerization

The recent focus of media and governments on renewability, green chemistry, and circular economy has led to a surge in the synthesis of renewable monomers and polymers. In this review, focussing on renewable monomers for reversible deactivation radical polymerizations (RDRP), it is highlighted that for the majority of the monomers and polymers reported, the claim to renewability is not always accurate. By closely examining the sustainability of synthetic routes and the renewability of starting materials, fully renewable monomers are identified and discussed in terms of sustainability, polymerization behavior, and properties obtained after polymerization. The holistic discussion considering the overall preparation process of polymers, that is, monomer syntheses, origin of starting materials, solvents used, the type of RDRP technique utilized, and the purification method, allows to highlight certain topics which need to be addressed in order to progress toward not only (partially) renewable, but sustainable monomers and polymers using RDRPs.

Modulation of side chain crystallinity in alternating copolymers

A remarkable enhancement in crystalline melting temperature (T_m) was observed in a series of fatty acids and mPEG containing alternating copolymers with the lone increase in mPEG chain lengths.

Stearoyl-appended pendant amino acid-based hyperbranched polymers for selective gelation of oil from oil/water mixtures

Stearic acid-appended pendant amino acid-based poly(methacrylate) hyperbranched polymers were developed for the phase-selective organogelation of crude oil from a binary mixture of oil/water.

Fatty Acid-Based Radically Polymerizable Monomers: From Novel Poly(meth)acrylates to Cutting-Edge Properties

The increasing price of barrels of oil, global warming, and other environmental problems favor the use of renewable resources to replace the petroleum-based polymers used in various applications. Recently, fatty acids (FAs) and their derivatives have appeared among the most promising candidates to afford novel and innovative bio-based (co)polymers because of their ready availability, their low toxicity, and their high versatility. However, the current literature mostly focused on FA-based polymers prepared by condensation polymerization or oxypolymerization, while only a few works have been devoted to radical polymerization due to the low reactivity of FAs through radical process. Thus, the aim of this Review is to give an overview of (i) the most common synthetic pathways reported in the literature to provide suitable monomers from FAs and their derivatives for radical polymerization, (ii) the available radical processes to afford FA-based (co)polymers, and (iii) the different applications in which FA-based (co)polymers have been used since the past few years.

Synthesis of Bioacrylic Polymers from Dihydro-5-hydroxyl furan-2-one (2H-HBO) by Free and Controlled Radical Polymerization

In this work, dihydro-5-hydroxyl furan-2-one (2H-HBO), a renewable-sourced chemical containing the hydroxyl functionality, is converted into its acrylic counterpart for the first time through a green chemical procedure using methacrylic anhydride. This newly synthesized acrylic monomer is able to be polymerized using different techniques such as bulk, solution, and emulsion polymerization. The ability of this monomer to copolymerize with other commercially available acrylates is studied using emulsion polymerization techniques. The pendent lactone ring remains unopened during polymerization and the new monomer is able to copolymerize with other acrylates such as methyl methacrylate and styrene. Reversible addition-fragmentation chain transfer reaction emulsion polymerization is also studied with the same monomer, leading to a steady conversion (∼60%) with a low polydispersity of 1.06. The homopolymer produced from such an emulsion polymerization shows a higher molecular weight than that produced from other methods, with a glass transition temperature of around 105 °C. This demonstrates the potential of this monomer as an interesting, green replacement for methyl methacrylate in certain fields of application.

Multiple Segmental Processes in Polymers with cis and trans Stereoregular Configurations

Altering the stereochemistry of a single double bond in the side group of a polymer resulted in systems with unprecedented local dynamics. These include (i) the appearance of three segmental processes in the cis-polymers all with Vogel-Fulcher-Tammann (VFT) temperature dependence, (ii) the low steepness index associated with fragility, m, and (iii) the lowest pressure coefficient of T_g, dT_g/dP, ever reported for polymers. We show that it is the inability of the cis-polymer to pack the side groups efficiently that controls the dynamics. Furthermore, the trans-polymers have the ability to crystallize. The wealth of dynamics reflects the cis/trans stereochemistry and the presence of different dipoles at specific positions sampling both the side group and backbone dynamics.

Highly efficient strategies toward sustainable monomers and polymers derived from fatty acids via tetramethylguanidine promoted esterification

Three efficient strategies were developed to transform fatty acids into mono-functional monomers and thermoplastic polymers by using 1,1,3,3-tetramethylguanidine promoted esterification.

Rational design of a biomimetic glue with tunable strength and ductility

A biomimetic design has been explored to achieve high-performance polymer glue with tuneable strength and ductility, which is suitable for a wide-range of substrates under both similar and dissimilar bonding.

Structure of solid lipid nanoparticles produced by a microwave-assisted microemulsion technique

The current study investigates the structure of solid lipid nanoparticles, prepared using a recently reported microwave-assisted microemulsion technique, by multi-angle static and dynamic light scattering and small angle X-ray scattering techniques.

Self-assembly of well-defined fatty acid based amphiphilic thermoresponsive random copolymers

Side-chain stearic acid containing thermoresponsive and crystalline random copolymers are synthesized via RAFT technique, which self-assembled to spherical micellar structures in aqueous solution depending on stearate content in the copolymer.

Controlled RAFT synthesis of side-chain oleic acid containing polymers and their post-polymerization functionalization

We report the synthesis and characterization of well-defined polymers from oleic acid as the bio-renewable resource. Double bonds in oleate side-chains in the polymer are further modified by thiol-ene reaction, epoxidation, and cross-linking.