Evolution of high-temperature molecular relaxations in poly(2-(2-methoxyethoxy)ethyl methacrylate) upon network formation.

Copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (poly(MEOMA)) are regarded as bioinert replacements of poly(-isopropylacrylamide) in some biomedical applications. Networks of poly(MEOMA) of various architecture form thermo-responsive hydrogels. Here, we present dielectric and mechanical spectroscopy studies on segmental motions and network relaxation processes in linear poly(MEOMA) and its networks - bare network and the network grafted with short poly(MEOMA) chains. We show that the α process assigned to the segmental motions of poly(MEOMA) is independent on the polymer topology and the glass transition temperature, , associated with this process equals 235-236 K for all investigated systems. The α' relaxation observed above by dynamical mechanical analysis is assigned to the sub-Rouse process. It strongly depends on the polymer network architecture and slows down by four orders of magnitude upon network formation.