Thermo-sensitive switching membranes regulated by pore-covering polymer brushes
Thermo-sensitive switching membranes regulated by pore-covering polymer brushes
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DOI：
10.1016/s0376-7388(03)00182-0
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发表时间：
2003-07
影响因子：
9.5
通讯作者：
Biao Yang;Wantai Yang
中科院分区：
文献类型：
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作者：
Biao Yang;Wantai Yang
以二苯甲酮（BP）为引发剂，将N-异丙基丙烯酰胺（NIPAAm）光接枝到聚对苯二甲酸乙二醇酯（PET）轨道膜上，制备了新型的覆孔聚合物刷调控的温敏开关膜。考察了溶剂、引发剂浓度和温度对接枝反应的影响。ATR-FTIR和SEM证实了聚NIPAAm刷固定在暴露于紫外光的膜表面，而不是孔内。接枝层的厚度可以通过接枝率来调节接枝反应参数。膜通量的调节是通过接枝链延伸进入膜孔的孔覆盖效应实现的。随着温度的变化，聚NIPAAm膜刷的溶胀和收缩使膜的孔径发生变化，从而调节膜通量。当接枝率超过1%时，0.2μ m接枝膜在30-35°C温度范围内不表现出明显的热敏阀效应。对于0.4μm膜，接枝刷的长度不足以覆盖膜孔，因此需要交联剂。交联网络限制了接枝聚合物刷的自由移动，从而使临界温度向高温移动。
Novel thermo-sensitive switching membrane regulated by pore-covering polymer brushes was prepared by photografting N-isopropylacrylamide (NIPAAm) onto the polyethylene terephthalate (PET) track membranes with benzophenone (BP) as initiator. The influence of solvent, initiator concentration and temperature on photografting has been investigated. ATR-FTIR and SEM confirmed that poly-NIPAAm brushes were immobilized on the membranes surface exposed to the UV light instead of inside the pores. The thickness of grafted layer can be adjusted by grafting reaction parameters via grafting degree. The membrane flux is regulated by pore-covering effect that comes from the grafted chains’ stretching into the membrane pores. Responding to the change of the temperature, the pore size varied with the swelling and shrinkage of poly-NIPAAm brushes and accordingly adjusted the membranes flux. The 0.2μm-grafted membranes do not show a remarkable thermo-sensitive valve effect near the range of 30–35°C until the grafting degree exceeds 1%. To 0.4μm membrane, the grafted brushes are not long enough to cover the membrane pores and thus crosslink agent is necessary. The crosslink network limit the free movement of grafted polymer brushes and thus the critical temperature has a shift to high temperature.