Influence of Freely Mobile Grafted Chain Length on Dynamic Properties of Comb-Type Grafted Poly(N-isopropylacrylamide) Hydrogels

摘要: Amino semitelechelic poly(N-isopropylacrylamide)s (PIPAAm) with three different molecular weights were synthesized by telomerization of IPAAm monomer 2-aminoethanethiol as a chain transfer agent, changing the molar ratio to agent. Macromonomers thermosensitive PIPAAm condensation reaction amino N-acryloxysuccinimide. The macromonomers determined titration terminal groups 2900, 4000, and 9000, respectively. comb-type grafted hydrogels having lengths graft chains radical copolymerization macromonomer in presence N,N'-methylenebisacrylamide cross-linker. An important aspect graft-type gels is construction architecture from normal type ofgel even though composition same. Higher equilibrium swellings at lower temperatures observed contrast normal-type gel, longer resulted higher swelling due freely mobile chains. Both exhibited reversible swelling-deswelling changes aqueous milieu response an alteration temperature. deswelling kinetics 40 °C changed states 10 °C, however, remarkable differences, rapid responses for gels. dehydration during gel shrinking was confirmed analysis DSC measurements. These dehydrated strongly aggregated hydrophobic intermolecular forces, inducing attractive forces operating between larger chains, resulting faster deswelling. A mechanism distinct polymer network collective diffusion demonstrated these network.