pH或/和温度双重响应嵌段接枝膜的开关特性

利用原子转移自由基聚合法(ATRP)成功地制备了聚甲基丙烯酸-嵌段-聚N-异丙基丙烯酰胺(PMN)和聚N-异丙基丙烯酰胺-嵌段-聚甲基丙烯酸(PNM)接枝开关膜。通过通量实验系统考察了两类开关膜分别或同时对pH和温度的响应性。结果表明:用ATRP法接枝嵌段共聚物开关中第一段接枝物的接枝率总是高于第二段接枝物的接枝率;该嵌段接枝开关膜对pH和温度同时响应的开关系数要大于其对单一pH或温度响应的开关系数;嵌段接枝开关中第一段接枝物对膜孔的开或关起主导作用,而第二段接枝物的影响相对较小。实验结果还表明,PMAA的pH响应开关系数比PNIPAM的温度响应开关系数显著。研究结果为设计和制备双重或多重嵌段接枝开关膜提供了有价值的参考。

Gating characteristics of dual pH-/thermo-responsive membranes with grafted diblock copolymers

Gating membranes with grafted diblock poly(methacrylic acid)- block-poly(N-isopropylacylamide) (PMN) and poly(N-isopropylacylamide)-block-poly(methacrylic acid) (PNM) are successfully prepared via surface-initiated atom transfer radical polymerization (ATRP).The dual pH-/thermo-responsive property of these membranes are systematically investigated by buffer solution permeation experiments at different pH values and temperatures. Results indicate that the grafting yields of the first blocks grafted in the diblock polymers are always higher than those of the second ones. The responsive gating coefficients of the prepared membranes triggered by simultaneous pH and temperature stimuli are much higher than that triggered by single pH or temperature stimulus. The gating characteristics of the membranes are mainly dominated by the first blocks in the grafted diblock polymers, and the second blocks have smaller effect on it. The pH-responsive gating coefficient of grafted PMAA chains is more significant than the thermo-responsive gating coefficient of grafted PNIPAM chains. The results in this study provide valuable guidance for designing and preparing dual- or multi-responsive gating membranes.