Sustainable Multiblock Copolymer Elastomers Derived from Lignin with Tunable Performance toward Strong Adhesives and UV-Shielding Materials

Abstract

With the increasing concern about global environmental issues, reducing the carbon footprint to achieve carbon neutrality has been particularly important. Sustainable multiblock copolymer elastomers (MBCPEs) have received tremendous interest due to their unprecedented performance and huge potential applications. However, complex multistep polymerization and postpolymerization processes are needed to design MBCPEs. In this work, a series of MBCPEs, in which vanillin acrylate (VA) derived from lignin was selected as the renewable rigid segments for the glassy block, while methyl acrylate (MA) was chosen as the soft segments for the rubbery block, were prepared by two successive reversible addition–fragmentation chain transfer (RAFT) polymerization processes with polytrithiocarbonate (PTTC). These thermally stable MBCPEs exhibit distinct microphase-separated morphology, where the hard poly­(vanillin acrylate) (PVA) blocks self-assemble into discrete glassy domains serving as the physical cross-linking points in the soft poly­(methyl acrylate) (PMA) matrix. The macroscopic mechanical performance, such as tensile strength, stretchability, toughness, and elastic recovery, can be adjusted well by changing the molecular weights and PVA contents. Moreover, these sustainable MBCPEs can be applied as strong adhesives and excellent UV-shielding materials, broadening their potential applications. This novel strategy is convenient and robust by combining RAFT polymerization and renewable resources toward high-performance MBCPEs, which can open a new avenue for the development of sustainable biobased elastomers.

One-pot strategy to access dynamic dual network from lignin-initiated star polymers by side reaction and transesterification

“…Specifically, L-P(BA 350 - co -GMA 150 ) b -SA could achieve a lap shear strength of 4.083 MPa, approximately three times higher than that of P(BA 350 - co -GMA 150 ) b -SA. While previous studies often reported increased strength but decreased toughness upon adding lignin to systems, 21,28,32,44 it is noteworthy that both strength and toughness were enhanced in our work, underscoring the significant influence of lignin as a copolymer core on mechanical properties. However, the performance of L-P(BA 250 - co -GMA 250 ) b -SA declined, possibly due to excessive crosslinking density leading to increased brittleness in the material.…”

“…This phenomenon arises from the introduction of functional groups such as 2-bromo-isobutyryl bromide and carbon disulfide onto THF-L, resulting in covalent bonds with lower energy within the macromolecule. The DTG profiles clearly indicate temperature ranges of weight loss: between 100 °C and 300 °C, corresponding to the degradation of –C–Br, –C–S, and –CS bonds, 44 while the degradation stage observed beyond 300 °C in all three samples is attributed to the degradation of the benzene ring in lignin. 32…”

Vanillin-Based Polymers via Ring-Opening Metathesis Polymerization

“…The hydroxyl functional group in vanillin often serves as a starting point for chemical transformation, enabling the synthesis of biobased polymers. For example, vanillin can be acrylated to form polymerizable vinyl monomers, which can then be polymerized using controlled radical polymerization techniques such as reversible addition–fragmentation chain transfer (RAFT) or atom transfer radical polymerization (ATRP) to produce functional polymers. − Additionally, by further cross-linking through the combination of aldehyde pendent groups of vanillin, biobased resins can be created. − While controlled radical polymerization offers many advantages, it also has inherent drawbacks, such as prolonged reaction times, high reaction temperatures, and chain transfer side reactions. In this context, ring-opening metathesis polymerization (ROMP) can serve as an excellent alternative to radical polymerization.…”