Sustainable Elastomers from Renewable Biomass

Abstract

Sustainable elastomers have undergone explosive growth in recent years, partly due to the resurgence of biobased materials prepared from renewable natural resources. However, mounting challenges still prevail: How can the chemical compositions and macromolecular architectures of sustainable polymers be controlled and broadened? How can their processability and recyclability be enabled? How can they compete with petroleum-based counterparts in both cost and performance? Molecular-biomass-derived polymers, such as polymyrcene, polymenthide, and poly(ε-decalactone), have been employed for constructing thermoplastic elastomers (TPEs). Plant oils are widely used for fabricating thermoset elastomers. We use abundant biomass, such as plant oils, cellulose, rosin acids, and lignin, to develop elastomers covering a wide range of structure-property relationships in the hope of delivering better performance. In this Account, recent progress in preparing monomers and TPEs from biomass is first reviewed. ABA triblock copolymer TPEs were obtained with a soft middle block containing a soybean-oil-based monomer and hard outer blocks containing styrene. In addition, a combination of biobased monomers from rosin acids and soybean oil was formulated to prepare triblock copolymer TPEs. Together with the above-mentioned approaches based on block copolymers, multigraft copolymers with a soft backbone and rigid side chains are recognized as the first-generation and second-generation TPEs, respectively. It has been recently demonstrated that multigraft copolymers with a rigid backbone and elastic side chains can also be used as a novel architecture of TPEs. Natural polymers, such as cellulose and lignin, are utilized as a stiff, macromolecular backbone. Cellulose/lignin graft copolymers with side chains containing a copolymer of methyl methacrylate and butyl acrylate exhibited excellent elastic properties. Cellulose graft copolymers with biomass-derived polymers as side chains were further explored to enhance the overall sustainability. Isoprene polymers were grafted from a cellulosic backbone to afford Cell-g-polyisoprene copolymers. Via cross-linking of these graft copolymers, human-skin-mimic elastomers and high resilient elastomers with a well-defined network structure were achieved. The mechanical properties of these resilient elastomers could be finely controlled by tuning the cellulose content. As isoprene can be produced by engineering of microorganisms, these elastomers could be a renewable alternative to petroleum products. In summary, triblock copolymer and graft copolymer TPEs with biomass components, skin-mimic elastomers, high resilient biobased elastomers, and engineering of macromolecular architectures for elastomers are discussed. These approaches and design provide us knowledge on the potential to make sustainable elastomers for various applications to compete with petroleum-based counterparts.

An Ionomeric Renewable Thermoplastic from Lignin‐Reinforced Rubber

“…Because of this increased ionic crosslinking, the shear-thinning thermoplastic ionomers show superior melt-elasticity. These materials along with many other sustainable products [23] might be used in construction components such as building siding, automotive oil-resistant thermoplastic rubbers, [24] and outdoor products with improved ultraviolet and oxidation resistance. [25] Anionic lignin, formed during alkaline deconstruction of biomass for the separation of lignin and cellulose, can be used to make high-value renewable thermoplastics.…”

“…Because of this increased ionic crosslinking, the shear‐thinning thermoplastic ionomers show superior melt‐elasticity. These materials along with many other sustainable products might be used in construction components such as building siding, automotive oil‐resistant thermoplastic rubbers, and outdoor products with improved ultraviolet and oxidation resistance …”

Sustainable rubbers and rubber additives

“…Ganewatta et al . prepared thermoplastic elastomers from natural rosin and modified vegetable oil, and discussed other sustainable elastomers from renewable biomass . Plant based phenolic acids with varying functionalities were utilized to prepare thiol‐ene elastomers using a photoinitiator …”

Sustainable self‐healing elastomers with thermoreversible network derived from biomass via emulsion polymerization

“…Recently, a few articles have been reported on the opportunities, modification, and production of new green polymeric materials. Sustainable materials from biomass are gaining attention due to shortage of fossil resources and deteriorated environmental conditions over the time . Naturally occurring polymers such as cellulose, protein, and natural rubber have been widely utilized to design polymeric products .…”

“…Sustainable materials from biomass are gaining attention due to shortage of fossil resources and deteriorated environmental conditions over the time. [1][2][3] Naturally occurring polymers such as cellulose, protein, and natural rubber have been widely utilized to design polymeric products. [4][5][6] On the contrary, production of synthetic polymer from biomass, such as vegetable oils, terpenes, sugar, furfural, lignin, and lactic acid, is a fast-growing research area.…”