Sustainable Microcrystalline Cellulose-graft-Diblock Bottlebrush Copolymer Elastomers Derived from All Biomass Sources

A kind of sustainable bottlebrush copolymer microcrystalline cellulose-graft-poly(lauryl methacrylate)-block-poly(isobornyl methacrylate) (MCC-g-PLMA-b-PIBOMA) was designed and synthesized via the activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) utilizing a halide exchange technique. A series of MCC-g-PLMA-b-PIBOMA was obtained by introducing the biomass-derived PLMA-b-PIBOMA side chains to the rigid cellulose backbone, for which PLMA and PIBOMA acted as a soft midblock and a hard outer block, respectively. Due to grafting of diblock side chains from the cellulose backbone, these graft copolymers possessed remarkable thermostability and enhanced mechanical property, which could be tuned with various molecular masses of the PIBOMA hard block, making them range from a thermoplastic to a thermoplastic elastomer. Distinct immiscibility between PLMA and PIBOMA blocks facilitated microphase separation, which built up a physical cross-linking network, as confirmed by atomic force microscopy and small-angle X-ray scattering measurements. This work provided a feasible and simple synthesis method for producing all biomass-derived bottlebrush graft copolymer elastomers, which had potential as an alternative candidate for petroleum-based elastomers.