Design of temperature-responsive polymers with enhanced hysteresis: alpha,alpha-disubstituted vinyl polymers
Takeshi Mori1, Suguru Beppu, Mohamed R Berber
1Department of Applied Chemistry, Kyushu University, 744 Moto-oka Nishi-ku, Fukuoka 819-0395, Japan.
Abstract:
Three temperature-responsive polymers which are alpha,alpha-disubstituted vinyl polymers having two amphiphilic groups (ethylamide or ethylester) per monomeric unit were designed. Two of these polymers showed unusually large hysteresis in their phase transition temperatures between a heating and a cooling process. This hysteresis resulted from the extremely slow kinetics of the dissolution process of the aggregated polymer chains in the cooling process due to intra- and interchain interactions including hydrogen bonding and hydrophobic interaction. The high density of the amphiphilic substituents on the polymer chain due to the alpha,alpha-disubstituted structure enhanced these intra- and interchain interactions. The large hysteresis was also observed in the volume change of a corresponding hydrogel. These new classes of temperature-responsive polymers are interesting materials because their large hystereses can be regarded as erasable memory function.
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