Superelastomers is an emerging class of thermoplastic elastomers (TPEs) with a rubbery backbone and glassy side chains exhibiting low residual strains and excellent elongation at break as compared to conventional TPEs. In this study, the structure-property relationship in this new class of materials is investigated by synthesizing well-defined mutligraft copolymers exhibiting a rubbery poly(n-butyl acrylate) backbone and sulfonated polystyrene side chains. The use of living anionic polymerization to prepare the PS macromonomers enables a free radical copolymerization with n-butyl acrylate yielding multigraft copolymers with controlled molecular weights and regularly spaced PS side chains. One of the advantages of using acrylic monomers as the rubbery backbone is that the monomer precursors have much better chemical resistance in oxidation than isoprene or butadiene monomers. Furthermore, slightly sulfonating the PS side chains will introduce more stiffness into the system while keeping the elasticity on desirable levels. One can thus tailor the mechanical properties of the final materials by taking advantage of the architecture, composition and the ability of those systems to self-assemble. A thorough characterization of the tensile and rheological properties of the synthesized polystyrene-poly(n-butyl acrylate) multigraft copolymers was performed and new insights for tailored design of superelastomers are discussed. Increasing the number of branches by 1, true stress takes same values (2.4MPa) and storage and loss modulus are increased by 1 order of magnitude, while elongation maintains similar highly values (1400%). Furthermore, sulfonating the PS side chains only by 13% results in a significant increase of true stress (from 2.4MPa to 38MPa). Sulfonation also introduces a notable increase of storage and loss modulus by 2 orders of magnitude, while engineering strain is decreased from 1400% to 750%.

Design and synthesis of acrylate-based sulfonated superelastomers

253rd National Meeting (2017)

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