Soft Elastomers via Introduction of Poly(butyl acrylate) "Diluent" to Poly(hydroxyethyl acrylate)-Based Gel Networks

We report a new strategy for the synthesis of stable and well-defined supersoft elastomers. First, four-arm star-like polymers, poly(trimethylsilyloxyethyl acrylate), were synthesized and cross-linked to form a relatively uniform polymer gel network. Second, short poly(n-butyl acrylate) side chains were grown from the initiating sites along the network backbone via atom transfer radical polymerization. These soft side chains act as low molecular weight "diluent" that "swells" the cross-linked polyHEA network, but cannot be leached from it. Using this strategy, materials with shear modulus less than 5 kPa were prepared and the effect of grafted side chain fraction on their mechanical properties was explored.