Kosik Katalin, Wilk Erzsébet, Geissler Erik, László Krisztina
Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest 1521, Hungary.
J Phys Chem B. 2008 Jan 31;112(4):1065-70. doi: 10.1021/jp075227w. Epub 2008 Jan 9.
Copolymerization of thermosensitive hydrogels based on poly(N-isopropylacrylamide) (PNIPA) is a possible route to enhanced storage capacity of guest molecules. This article describes the synthesis of the amphiphilic crown ether N9-propenoyl-3,6,12,15-tetraoxa-9,21-diazabicyclo[15.3.1]heneicosa-1(21),17,19-triene (CE) and its incorporation into a PNIPA hydrogel (PNIPA/CE). Mechanical measurements on the gel show that the CE units contribute to the elasticity of the network, but the swelling ratio in water is reduced compared to the unmodified system. The comonomer reduces the temperature of the volume phase transition (VPT), TVPT, and broadens the transition. Both the enthalpy and the entropy associated with the VPT decrease. Scattering measurements indicate that the local structural features on the scale of 10 A are unchanged, but the CE units form large clusters, the size of which increases with rising temperature. In the phase-separated state above TVPT these clusters are distributed on the polymer-water interface.
基于聚（N-异丙基丙烯酰胺）（PNIPA）的热敏水凝胶的共聚是提高客体分子存储容量的一种可能途径。本文描述了两亲性冠醚N9-丙烯酰基-3,6,12,15-四氧杂-9,21-二氮杂双环[15.3.1]二十一碳-1(21),17,19-三烯（CE）的合成及其掺入PNIPA水凝胶（PNIPA/CE）中。对该凝胶的力学测量表明，CE单元有助于网络的弹性，但与未改性体系相比，其在水中的溶胀率降低。共聚单体降低了体积相转变（VPT）温度TVPT，并拓宽了转变范围。与VPT相关的焓和熵均降低。散射测量表明，10 Å尺度上的局部结构特征未发生变化，但CE单元形成了大的聚集体，其尺寸随温度升高而增大。在高于TVPT的相分离状态下，这些聚集体分布在聚合物-水界面上。
