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Reentrant phase transition and fast responsive behaviors of poly{ N ‐[3‐(dimethylaminopropyl)] methacrylamide} hydrogels prepared in poly(ethylene glycol) solutions
Author(s) -
Demirel Gökçen Birlik,
Çaykara Tuncer
Publication year - 2009
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.30120
Subject(s) - methacrylamide , self healing hydrogels , polymer chemistry , polymerization , materials science , ethylene glycol , swelling , monomer , peg ratio , chemical engineering , aqueous solution , radical polymerization , polymer , chemistry , organic chemistry , composite material , acrylamide , finance , engineering , economics
Macroporous temperature‐sensitive poly { N ‐[3‐(dimethylaminopropyl)] methacrylamide} hydrogels were synthesized by free‐radical crosslinking polymerization of the monomer N ‐[3‐(dimethylaminopropyl)] methacrylamide and the crosslinker N,N ′‐methylenebisacrylamide in aqueous solutions at 22°C. Poly(ethylene glycol) (PEG) with a molecular weight of 1000 g/mol was used as the pore‐forming agent during the polymerization reaction. The concentration of PEG in the polymerization solutions was varied between 0 and 18 wt %, whereas the crosslinker ( N,N ′‐methylenebisacrylamide) concentration was fixed at 2 wt % (with respect to the monomer). The effects of the PEG concentration on the thermo‐induced phase‐transition behavior and the chemical structure, interior morphology, and swelling/deswelling kinetics were investigated. Normal‐type hydrogels were also prepared under the same conditions without PEG. An interesting feature of the swelling behavior of both the normal‐type and macroporous hydrogels was the reentrant phase transition, in which the hydrogels collapsed once and reswelled as the temperature was continuously increased. Scanning electron micrographs revealed that the interior network structure of the hydrogels prepared in PEG solutions became more porous with an increase in the PEG concentration in the polymerization solution. This more porous matrix provided numerous water channels for water diffusion in or out of the matrix and, therefore, an improved responsive rate to external temperature changes during the deswelling and swelling processes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009