Comparison of the Thermoresponsive Deswelling Kinetics of Poly(2-(2-methoxyethoxy)ethyl methacrylate) Hydrogels Prepared by ATRP and FRP

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.

Thermoresponsive hydrogel scaffolds with tailored hydrophilic pores

Thermoresponsive hydrogels with efficient water-release channels were prepared by incorporating star-shaped macromolecular pore precursors, with degradable disulfide crosslinked cores and hydrophilic poly(ethylene oxide) (PEO) arms, into the gel network. The gel framework exhibiting lower critical solution temperature (LCST) behavior was synthesized by atom transfer radical polymerization (ATRP) of 2-(2-methoxyethoxy)ethyl methacrylate and ethylene glycol dimethacrylate. The incorporation of degradable star macromolecules (dSM) was facilitated by growing the gel from ATRP initiator sites contained within their cores. Following the formation of the gel, the dSM cores were degraded, yielding uniform pores lined with hydrophilic PEO chains. The effect of hydrophilic pores on thermoresponsive hydrogel performances was studied by comparing hydrogels containing hydrophilic pores with analogous hydrogels with neutral pores or with pore-free controls. Dye absorption/release experiments pointed to the suitability of newly synthesized hydrogels as controlled-release media, for example, for drug delivery. Cell culture experiments confirmed their nontoxicity and biocompatibility (cell viability >98%).