Bio-based Elastomer Research Articles

Sustainable chitin-derived elastomers via grafting strategy with tunable mechanical and adhesion properties

With increasing environmental awareness and the pursuit of sustainable development goals, environmentally friendly sustainable thermoplastic elastomers (TPEs) derived from natural resources are highly desired to replace traditional TPEs. However, preparing sustainable TPEs with high mechanical properties and multifunctionality from biobased feedstocks remains a significant challenge. In this work, a series of chitin-graft-poly(acrylamide-co-2-ethylhexyl acrylate) (Chitin-g-P(AM-co-EHA)) copolymers were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization. The tensile strength of Chitin-g-P(AM-co-EHA) copolymers can be tuned over a wide range from 1.0 to 7.3 MPa by adjusting the chitin and PAM contents. Benefiting from the brush-like architecture, Chitin-g-P(AM-co-EHA) copolymer exhibits improved mechanical properties over its linear counterparts. Moreover, these Chitin-g-P(AM-co-EHA) copolymers show good adhesion performance on different substrates. The shear strength can achieve 7.5 MPa for Chitin0.8-PAM50, which is high enough for commercial applications. The combination of chitin and grafting strategy can promote the development of strong chitin-based sustainable elastomers. This approach can be further utilized to design novel high-performance biobased elastomers and adhesives derived from natural resources.

Biomass and Transparent Supramolecular Elastomers for Green Electronics Enabled by the Controlled Growth and Self-Assembly of Dynamic Polymer Networks.

Determining the optimal method for preparing supramolecular materials remains a profound challenge. This process requires a combination of renewable raw materials to create supramolecular materials with multiple functions and properties, including simple fabrication, sustainability, a dynamic nature, good toughness, and transparency. In this work, a strategy is presented for toughening supramolecular networks based on solid-phase chain extension. This toughening strategy is simple and environmentally friendly. In addition, a series of biobased elastomers are designed and prepared with adjustable performance characteristics. This strategy can significantly improve the transparency, tensile strength, and toughness of the synthesized elastomer. The synthesized biobased elastomers have great ductility, repairability, and recyclability, and they show good adhesion and dielectric properties. A biobased ionic skin is assembled from these biobased elastomers. Assembled ionic skin can sensitively detect external stimuli (such as stretching, bending, compression, or temperature changes) and monitor human movement. The conductive and dielectric layers of the biobased ionic skin are both obtained from renewable raw materials. This research provides novel molecular design approaches and material selection methods for promoting the development of green electronic devices and biobased elastomers.

Novel bio-based polyurethane elastomers for adjustable room-temperature damping property

The distinctive viscoelastic behavior of elastomeres can be exploited for reducing vibrations and noise. However, the utility of conventional rubber-based elastomers is limited by low glass transition temperature (Tg) and narrow adjustable damping range, which constrain the room-temperature damping property. Moreover, the majority of rubber-based elastomers are sourced from unsustainable petroleum-based resources. Therefore, designing bio-based materials with room-temperature high-damping property to replace conventional rubber-based elastomers is crucial. Herein, a novel bio-based polyurethane (bio-PU) elastomer with an adjustable damping-temperature range and room-temperature high-damping property is successfully synthesized from bio-based poly (trimethylene ether) glycol. The effects of molecular chain structure on the thermal properties, mechanical properties, and adjustable damping-temperature range of the bio-PU elastomers, along with the mechanisms underlying these effects, are elucidated in detail. As the content of hard segment increasing, the Tg of bio-PU elastomers significantly increases from −13.0 to 29.9 °C, effectively encompassing the damping temperature range within the room-temperature working range. This promising strategy for formulating bio-based elastomers with adjustable damping-temperature range can advance the sustainable growth of PU industry and broaden the scope of PU damping applications.

High-Performance Biobased Elastomers with Both High Strength and High Toughness

High-Performance Biobased Elastomers with Both High Strength and High Toughness

Recent Developments in Synthesis, Properties, Applications and Recycling of Bio-Based Elastomers.

In 2021, global plastics production was 390.7 Mt; in 2022, it was 400.3 Mt, showing an increase of 2.4%, and this rising tendency will increase yearly. Of this data, less than 2% correspond to bio-based plastics. Currently, polymers, including elastomers, are non-recyclable and come from non-renewable sources. Additionally, most elastomers are thermosets, making them complex to recycle and reuse. It takes hundreds to thousands of years to decompose or biodegrade, contributing to plastic waste accumulation, nano and microplastic formation, and environmental pollution. Due to this, the synthesis of elastomers from natural and renewable resources has attracted the attention of researchers and industries. In this review paper, new methods and strategies are proposed for the preparation of bio-based elastomers. The main goals are the advances and improvements in the synthesis, properties, and applications of bio-based elastomers from natural and industrial rubbers, polyurethanes, polyesters, and polyethers, and an approach to their circular economy and sustainability. Olefin metathesis is proposed as a novel and sustainable method for the synthesis of bio-based elastomers, which allows for the depolymerization or degradation of rubbers with the use of essential oils, terpenes, fatty acids, and fatty alcohols from natural resources such as chain transfer agents (CTA) or donors of the terminal groups in the main chain, which allow for control of the molecular weights and functional groups, obtaining new compounds, oligomers, and bio-based elastomers with an added value for the application of new polymers and materials. This tendency contributes to the development of bio-based elastomers that can reduce carbon emissions, avoid cross-contamination from fossil fuels, and obtain a greener material with biodegradable and/or compostable behavior.

Design and preparation of a crosslinkable, oil-resistant, and bio-based elastomer from fumarate

Design and preparation of a crosslinkable, oil-resistant, and bio-based elastomer from fumarate

Facile preparation of near-monodisperse oligocellulose and its elastomeric derivatives with tunable mechanical properties

Oligocellulose (OC) with low polydispersity indices has been produced in large quantities using an improved method of acid-assisted hydrolysis, in which long cellulose chains disintegrate in concentrated phosphoric acid at moderately elevated temperatures. The hydrolysis time has been reduced by three orders of magnitude without compromising the overall yield of the process or the quality of OC products. The efficient production of high-quality OCs in large quantities allows for developing OC-derived elastomeric materials. A series of OC-graft-poly(isobornyl methacrylate-random-n-butyl acrylate) [OC-g-P(IBOMA-r-BA)] elastomers have been synthesized via activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP). OC-g-P(IBOMA-r-BA) elastomers have tunable molecular architectures and phase morphologies toward desirable mechanical properties and thermal stability suitable for various applications. The methodologies of the OC production and the graft-polymers synthesis in this study would help advance technologies for broader applications of bio-based elastomers.

A scalable human iPSC-based neuromuscular disease model on suspended biobased elastomer nanofiber scaffolds.

Many devastating neuromuscular diseases currently lack effective treatments. This is in part due to a lack of drug discovery platforms capable of assessing complex human neuromuscular disease phenotypes in a scalable manner. A major obstacle has been generating scaffolds to stabilise mature contractile myofibers in a multi-well assay format amenable to high content image (HCI) analysis. This study describes the development of a scalable human induced pluripotent stem cell (iPSC)-neuromuscular disease model, whereby suspended elastomer nanofibers support long-term stability, alignment, maturation, and repeated contractions of iPSC-myofibers, innervated by iPSC-motor neurons in 96-well assay plates. In this platform, optogenetic stimulation of the motor neurons elicits robust myofiber-contractions, providing a functional readout of neuromuscular transmission. Additionally, HCI analysis provides rapid and automated quantification of axonal outgrowth, myofiber morphology, and neuromuscular synapse number and morphology. By incorporating amyotrophic lateral sclerosis (ALS)-related TDP-43G298Smutant motor neurons and CRISPR-corrected controls, key neuromuscular disease phenotypes are recapitulated, including weaker myofiber contractions, reduced axonal outgrowth, and reduced number of neuromuscular synapses. Treatment with a candidate ALS drug, the receptor-interacting protein kinase-1 (RIPK1)-inhibitor necrostatin-1, rescues these phenotypes in a dose-dependent manner, highlighting the potential of this platform to screen novel treatments for neuromuscular diseases.

Solvent-Free Environmentally Friendly Method to Prepare Thermo-Reversible Fully Bio-Based Elastomers.

Most rubber products come from petrochemical resources, which are increasingly in short supply. Rubber products that formed irreversible chemical bonds in the vulcanization process are difficult to recycle, resulting in a serious waste of resources. Therefore, it is important to prepare a kind of reprocessable biobased elastomers. Using furfuryl methacrylate (FMA) as the modified monomer, poly(dibutyl itaconate-myrcene-furfuryl methacrylate) (PDBIMFA) was synthesized by high-temperature emulsion polymerization successfully. The structure and compositions of PDBIMFA were characterized by Fourier transform infrared and 1H NMR, and the effects of different FMA contents on the structures and properties of PDBIMFA were systematically studied. Based on the Diels-Alder reaction, bismaleimide (BMI) and carbon black (CB) were introduced into PDBIMFA as cross-linking agents and reinforcing fillers, respectively, by the melt blending method, and PDBIMFA-BMI elastomer materials and CB/PDBIMFA-BMI elastomer composites with thermo-reversible cross-linking characteristics were prepared. The effects of the ratio of FMA and BMI on the mechanical properties of PDBIMFA-BMI were studied. PDBIMFA-BMI and CB/PDBIMFA-BMI were reprocessed twice, and the recovery rate of tensile strength was both more than 90%. The addition of CB was found to play a reinforcing role in the elastomer and with the introduction of the amount of CB, the reprocessability of composite remained at a good level. It is hoped that this research will provide a new strategy for the sustainable development of bio-based elastomer materials.

Vitrimer-like, mechanically Robust, healable and recyclable biobased elastomers based on epoxy natural Rubbers, polylactide and layered double hydroxide

Vitrimer-like, mechanically Robust, healable and recyclable biobased elastomers based on epoxy natural Rubbers, polylactide and layered double hydroxide

Tough and strong sustainable thermoplastic elastomers nanocomposite with self-assembly of SI-ATRP modified cellulose nanofibers

The ingenious design of sustainable thermoplastic elastomers (STPEs) is of great significance for the goal of the sustainable development. However, the preparation of STPEs with good mechanical performance is still complicated and challenging. Herein, to achieve a simple preparation of STPEs with strong mechanical properties, two biobased monomers (tetrahydrofurfuryl methacrylate (THFMA) and lauryl methacrylate (LMA)) were copolymerized into poly (THFMA-co-LMA) (PTL) and grafted onto TEMPO oxidized cellulose nanofiber (TOCN) via one-pot surface-initiated atom transfer radical polymerization (SI ATRP). The grafting modified TOCN could be self-assembled into nano-enhanced phases in STPEs, which are conducive to the double enhancement of the strength and toughness of the STPEs, and the size of nano-enhanced phases is mainly affected by TOCN fiber length and molecular weight of grafting chains. Especially, with the addition of 7 wt% TOCN, tensile strength, tensile strain, toughness, and glass transition temperature (Tg) of TOCN based STPEs (TOCN@PTL) exhibited 140 %, 36 %, 215 %, and 6.8 °C increase respectively, which confirmed the leading level in the field of bio-based elastomers. In general, this work constitutes a proof for the chemical modification and self-assembly behavior of TOCN by one-pot SI ATRP, and provides an alternative strategy for the preparation of high-performance STPEs.

Toward Biosourced Elastomer from β-Farnesene and Styrene: Synthesis, Properties, and Mechanical Performance

Encouraged by the growing need for sustainability in the rubber industry, attempts have been made to fabricate biobased elastomers to replace existing petro-derived polymers for useful applications. Here, we demonstrate a simple and sustainable route to synthesize biobased elastomers based on β-farnesene (FA) and styrene (STY) under a high-temperature persulfate emulsion process for tire applications. The synthesized copolymer, poly(farnesene-co-styrene) (PFS), showed molecular weight (Mw) of 108 500 g/mol and 162 100 g/mol for 30 and 50 wt % styrene contents. The commoner reactivity ratios showed nonideal copolymerization behavior, as evaluated using Fineman–Ross and Kelen-Tüdös methods. The macromolecular chemical structure of PFS elastomers was confirmed by FT-IR and NMR analyses. The copolymer showed complete 1,4-cis and trans-microstructure formation. The glass-transition temperature (Tg) values of PFS elastomers were obtained in the range of −58 and −38 °C, depending on the styrene content. The PFS gum elastomers displayed improved thermal stability and single degradation pattern compared to the pristine polyfarnesene. Besides, carbon black was incorporated into the PFS elastomer matrix to prepare rubber vulcanizates for desired mechanical properties. The 50/50 FA/STY rubber vulcanizates displayed good tensile strength (4.43 MPa), elongation at break (183%). The 80/20 and 70/30 FA/STY rubber vulcanizates exhibited good wet skid resistance compared to its pristine polyfarnesene vulcanizate. This work provides an efficient approach to using emulsion polymerization for developing sustainable rubbers on an industrial scale for multifaceted applications.

Bioinspired ultra-tough, exceptionally stretchable, and self-recoverable bio-based coating for visual damage detection and self-healing

Developing intelligent materials with integrated ultra-high-performance damage monitoring and repair functions is of paramount significance for broadening the application of the latest generation of smart materials. Here, inspired by spider silk and biological skin, we embedded multiple hydrogen bonding motifs and rigid alicyclic groups with attached damage monitoring sensors in bio-based polyurethanes to create bio-based elastomers with exceptional mechanical properties combined with repair and damage monitoring functionalities. Benefiting from the abundance of multiple hydrogen bonding elements within the polyester backbone for fracture and remodeling as external energy dissipation, and the contribution of asymmetric alicyclic groups embedded in hard domains. The elastomer possesses exceptional toughness (583 MJ·m−3) and tensile strength (43 MPa), the elongation at break point is 2600 %, and self-healing (86 % at 60 °C for 6 h), environmental adaptability, and recyclability, thereby achieving the preparation of ultra-tough self-healing elastomeric materials. Simultaneously, the internally embedded sensors enable the localization and monitoring of damage through visually observable means, such as quenching and discoloration. The elastomer recovers well in 3.5 wt% NaCl solution and provides corrosion protection (9.23 × 107 Ω·cm2 even after 50 days of immersion), achieving the integration of ultra-high mechanical performance coating materials with damage warning and repair functions. Therefore, the molecular structure design scheme of the biomimetic elastomer provides constructive guidance for surface protection application of engineering equipment in service under harsh environments.

Biobased Polyamide 4,36 Thermoplastic Elastomer and its Cellulose Nanocomposites

AbstractThe search for fossil fuel‐based polymer alternatives has attracted significant attention over the past few decades. A biobased polyamide elastomer, namely PA4,36, is synthesized through a facile polycondensation of fatty acid‐based monomer and 1,4‐butanediamine. The chemical structure and molecular weight distribution of the polymer are characterized by Fourier infrared spectroscopy and gel permeation chromatography. PA4,36 displays a medium hardness (Shore A/Shore D = 97/50), a high stretchability (1116%), ease of melt processing, and hydrophobicity. The introduction of cellulose nanocrystals (CNCs) to the elastomer reduces the melting temperature and crystallization temperature due to the disturbance of CNCs on polymer crystallization, and influences its thermal degradation. It improves the glass transition temperature by up to 5.1 °C because of the restriction of the molecular mobility of the polymer by CNCs. It increases the storage modulus significantly from 1.5 GPa at 25 °C for neat PA4,36, to up to 10.8 GPa for the nanocomposite with 10 wt.% CNCs. The biobased elastomer and its CNC nanocomposites can be promising alternatives to some fossil fuel‐based elastomers with medium hardness.

The biomimetic design provides efficient self-healing of ultrahigh-tough and damage-warning bio-based elastomer for protective clothing of metals

The biomimetic design provides efficient self-healing of ultrahigh-tough and damage-warning bio-based elastomer for protective clothing of metals

Green and Catalyst-Free Cross-Linking of Bio-Based Elastomers toward Robust, Reprocessable Abilities and Improved Thermal Aging Resistance Enabled by β-Hydroxyl Esters

Green and Catalyst-Free Cross-Linking of Bio-Based Elastomers toward Robust, Reprocessable Abilities and Improved Thermal Aging Resistance Enabled by β-Hydroxyl Esters

Preparation of bio-based elastomer and its nanocomposites based on dimethyl itaconate with versatile properties

As the need for renewable and high-performance alternative elastomer grows, efforts have been made to develop bio-based elastic polymers for engineering applications. Herein, bio-based elastomers poly(dimethyl itaconate-co-butadiene)s (PDMIBs) were successfully synthesized by emulsion copolymerization of renewable monomer dimethyl itaconate (DMI) with partially petroleum-derived butadiene under mild conditions. It is an effective strategy to tailor PDMIB properties by comonomers with different feed ratios and to adjust the compositions and sequence distributions. The structure and thermal stability were investigated by FTIR, NMR, DSC analyses, etc. In terms of properties: (1) the vulcanizates showed excellent tensile strength (10.2 MPa), elongation at break (1146%) and toughness (37.6 MJ m−3) without filler reinforcement, which were obviously superior to the mechanical properties of most traditional petroleum-based synthetic rubbers; (2) Nanosilica-filled PDMIBs exhibited good mechanical properties, excellent abrasion resistance and oil resistance due to strong polarity in molecular chains; (3) Epoxy-functionalized poly(dimethyl itaconate-co-butadiene-co-glycidyl methacrylate) PDMIBG showed better silica dispersion and excellent dynamic mechanical properties. In summary, this new kind of bio-based elastomer PDMIBs can be used in multiple engineering applications, such as bio-based gloves, conveying belts, oil-resistant products and high-performance tire tread materials, etc. This study opens the door to the use of emulsion copolymerization and functionalization modification technology in the synthesis of new high-performance bio-based elastomer nanocomposites for the rubber industry.

Biosourced Poly(lactic acid)/polyamide-11 Blends: Effect of an Elastomer on the Morphology and Mechanical Properties.

Fully biobased polylactide (PLA)/polyamide-11 (PA11) blends were prepared by melt mixing with an elastomer intermediate phase to address the low elasticity and brittleness of PLA blends. The incorporation of a biobased elastomer made of poly(butylene adipate-co-terephthalate) (PBAT) and polyethylene oxide (PEO) copolymers was found to change the rigid interface between PLA and PA11 into a much more elastic/deformable one as well as promote interfacial compatibility. The interfacial tension of the polymer pairs and spreading coefficients revealed a high tendency of PEO to spread at the PLA/PA11 interface, resulting in a complete wetting regime (interfacial tension of 0.56 mN/m). A fully percolated rubbery phase (PEO) layer at the PLA/PA11 interface with enhanced interfacial interactions and PLA chain mobility contributed to a better distribution of the stress around the dispersed phase, leading to shear yielding of the matrix. The results also show that both the morphological modification and improved compatibility upon PEO addition (up to 20 wt %) contributed to the improved elongation at break (up to 104%) and impact strength (up to 292%) of the ternary PLA/PA11/PEO blends to obtain a super-tough multiphase system.

Mechanochemistry promoted in-situ compatibilization for highly toughened elastomer and super elastic foam

Elastic materials based on biomass fiber reinforced natural rubber (NR) composites featured by renewability, environmental friendliness, and outstanding toughness have attracted intensive attention. However, the improvement in tensile strength via natural fiber reinforcement is always accompanied by the compromise in toughness, which is rooted in the notoriously weak interfacial bonding originating from the significant mismatch in surface energies between constituent materials. In this work, we for the first time present a facile route to realize the interfacial activation of keratin fibers (KFs) derived from leather solid waste as well as the preparation of NR/KF composite with dual excellence in tensile strength and toughness via mechanochemistry. The activated thiol groups generated by mechanochemical pulverization promote the dispersion and in-situ compatibilization of KFs in rubber matrix, thereby facilitating effective interfacial stress transfer and enhancing the mechanical performance of the composites. As a result, the tensile strength, elongation, and toughness at break of composite elastomer reach 19.4 MPa, 781.0%, and 48.8 MJ/m3, respectively, outperforming the state-of-the-art natural fiber reinforced NR composites. Moreover, the incorporation of mechanochemical-pulverized KFs into NR matrix offers heterogeneous nucleation locales, facilitating the foaming of NR in supercritical carbon dioxide (ScCO2). The cell wall of the composite is in turn reinforced, and the resultant foam manages to deliver an excellent compressive recovery rate of 99.4% even after 200 cycles that outstrips those of reported foams. This work highlights a facile and green route to turn waste bovine hair in leather industry into high-performance bio-based elastomer and super-elastic foam.

Preparation and characterization of a new sustainable bio-based elastomer nanocomposites containing poly(glycerol sebacate citrate)/chitosan/n-hydroxyapatite for promising tissue engineering applications

Poly (glycerol sebacate citrate) (PGSC) has potential applications in tissue engineering due to its biodegradability and suitable elasticity. However, its applications are restricted owing to its acidity and high degradation rate. In this study, a new bio-nanocomposite based on PGSC has been synthesized by incorporating chitosan (CS) and various concentrations of hydroxyapatite nanoparticles (n-HA). It is assumed that the basicity of a CS and hydroxyl groups of n-HA will reduce the acidity of PGSC and control the rate of degradation. Also, the biocompatibility of n-HA and inherent hydrophilicity of CS can improve cell adhesion and proliferation of PGSC-based scaffolds. FTIR, XRD, FESEM, and EDX tests confirmed the synthesis of these nanocomposites and the interaction between each of the components. The results of the DMTA test also indicated the elastic behavior of the samples embedded with n-HA. The hydrophilicity assay demonstrated that the water contact angle of the scaffolds decreased as the concentration of n-HA augmented, and it reached the value of 44 ± 0.9° for nanocomposite containing 5 wt.% n-HA. The degradation rate of all PGSC nanocomposites was reduced due to the anionic groups of n-HA and CS. TGA assay indicated that the incorporation of n-HA led to the enhancement of scaffolds’ thermal stability. Furthermore, the synergistic effect of CS and n-HA on the enhancement of protein adsorption and cell proliferation was confirmed through protein adhesion and MTT assay, respectively. Consequently, the addition of n-HA and CS perform the new bio-nanocomposites scaffolds based on PGSC with sufficient hydrophilicity, flexibility, and thermal stability in tissue engineering applications.