Water and polymer dynamics in poly(hydroxyl ethyl acrylate-co-ethyl acrylate) copolymer hydrogels
(2391-2402) European Polymer Journal 47  #12 (2011)
Kyritsis et al, Greece, Germany, Japan studied water and polymer dynamics in hydrogels based on random copolymers of hydrophilic poly(hydroxyl ethyl acrylate) (PHEA) and hydrophobic poly(ethyl acrylate) (PEA) by of two dielectric techniques, thermally stimulated depolarization currents (TSDC) and, mainly, broadband dielectric relaxation spectroscopy (DRS).  The results show that the copolymers are homogeneous at nm scale, except at very high PEA content.  Distinct changes in the dielectric response, in particular in the time scale and the dielectric strength of the βsw relaxation, at the water content of the completion of the first hydration layer indicate that water molecules themselves contribute to the dielectric response at higher water contents.  (RDC 11/16/2011)

Swelling control in thermo-responsive hydrogels based on 2-(2-methoxyethoxy)ethyl methacrylate by crosslinking and copolymerization with N-isopropylacrylamide
(887-892) Polymer Journal 43 #11 (2011)
Abstract
García-García, et al of the Instituto de Ciencia y Tecnología de Polímeros, Spain, used two different strategies to modulate the swelling capacity of thermo-responsive hydrogels based on 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) in water.  In the first approach, several poly(MEO2MA) hydrogels were synthesized using different proportions of a conventional crosslinker, as tetra(ethylene glycol) dimethacrylate and a non-conventional inorganic crosslinker, as polyhedral oligomeric silsesquioxane (POSS) functionalized with eight methacrylic groups (POSS-meth8).  The experiments showed that the equilibrium swelling and the volume transition temperature (VTT) could be tuned by varying the crosslinker degree, regardless of the type of crosslinker. In the second approach, several poly(MEO2MA-co-N-iPAAm) hydrogels were prepared for the very first time, because N-isopropylacrylamide (N-iPAAm) is also a thermo-responsive component that increases the swelling capacity of the hydrogel in water. In addition, the VTT and the glass transition temperature of these new copolymer hydrogels could also be tuned by varying the monomeric composition.  (RDC 11/11/2011)