Synthesis of thermosensitive double-layer gel by polymer reaction

本研究的目的是建立用烷基胺1酰胺化聚丙烯酸凝胶-1,8-重氮杂环-[5,4,0]-7-十一烯盐（DAA）合成不对称热敏双层凝胶的方法。在80℃下，在三苯基亚磷酸酯的存在下，DAA与烷基胺的第一次酰胺化反应几乎是定量的，得到了相应的DAA-聚n -烷基丙烯酰胺（PNAA）核壳型凝胶。壳层厚度由反应时间控制。将DAA-PNAA核壳型凝胶与另一烷基胺在相同的条件下进行二次酰胺化，制备了PNAA(2)-PNAA(1)核壳型凝胶。PNAA(2)-PNAA(1)核-壳型凝胶的壳层和核的溶胀/消胀几乎独立地响应温度的变化。将圆柱形PNAA(2)-PNAA(1)核壳型凝胶切成两半，制备了半圆柱形双层凝胶。在PNAA(2)和PNAA(1)的较低临界溶液温度（LCSTs）之间的温度下，所得的半圆柱形双层凝胶在水中明显弯曲。通过温度的逐步变化，观察到可逆弯曲行为。然而，在边界上的破坏是逐渐发生的，因为弯曲的凝胶的形状是极度扭曲的。提出了一种制备不受这种变形破坏的不对称热敏PNAA(2)-PNAA(1)双层凝胶的新方法。制备了一种薄而长、不对称的热敏双层凝胶。这种凝胶可以弯曲成之字形，反应速度快。

The purpose of this study is to establish synthetic method of asymmetric, thermosensitive double-layer gel by amidation of poly(acrylic acid) gel-1,8-diazabicyclo-[5,4,0]-7-undecene salt (DAA) with alkylamine.1. The first amidation of DAA with alkylamines proceeded nearly quantitatively at 80℃ in the presence of triphenylphosphite to give the corresponding DAA-poly(N-alkylacrylamide) (PNAA) core-shell type gels. The thickness of the shell layer was controlled by the reaction time. PNAA(2)-PNAA(1) core-shell type gels were prepared by the second amidation of the DAA-PNAA core-shell type gel with another alkylamine under the similar conditions as the first amidation.2. The swelling/de-swelling of shell layers and cores in the PNAA(2)-PNAA(1) core-shell type gels occurred almost independently in response to the temperature changes.3. The semi-cylindrical, double-layer gels were prepared by cutting the cylindrical PNAA(2)-PNAA(1) core-shell type gels into halves.4. The resulting semi-cylindrical, double-layer gels were markedly bent in water at temperatures between the lower critical solution temperatures (LCSTs) of PNAA(2) and PNAA(1). The reversible bending behavior was observed in response to stepwise temperature changes cross the LCSTs. However, the destruction on the boundary occurred gradually, since the shape of the bent gel was extremely distorted.5. A new approach to the preparation of asymmetric thermosensitive PNAA(2)-PNAA(1) double-layer gels, which were not damaged by this deformation, by several procedures was proposed.6. A thin long, asymmetric, thermosensitive double-layer gel was prepared. This gel can be bent in zigzag with high-speed response.