Controlled pore functionalization of poly(ethylene terephthalate) track-etched membranes via surface-initiated atom transfer radical polymerization
Controlled pore functionalization of poly(ethylene terephthalate) track-etched membranes via surface-initiated atom transfer radical polymerization
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DOI：
10.1021/la7016962
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发表时间：
2007-09-25
期刊：
影响因子：
3.9
通讯作者：
Ulbricht, Mathias
中科院分区：
文献类型：
--
作者：
Friebe, Alexander;Ulbricht, Mathias
开发了一种在工业聚合物聚对苯二甲酸乙二醇酯（PET）上进行表面引发原子转移自由基聚合（ATRP）的新方法，该方法可以控制和估计径迹蚀刻膜等圆柱孔中接枝聚合物的层厚度。 PET表面经氧化水解处理后，通过两步固相反应将溴代烷基引发剂固定在PET表面；等孔膜结构得以保留，孔径由760 nm增大至790 nm。聚（N-异丙基丙烯酰胺）（PNIPAAm）在 ATRP 条件下在室温下从甲醇/水混合物中接枝。单体浓度和反应时间都可以作为调节接枝程度的参数。有效接枝层厚度及其对温度的响应是根据纯水渗透率来估计的。所有数据，尤其是25℃溶胀层中的高聚合物密度(0.37 g/cm(3))，表明已经实现了具有“刷”结构的接枝PNIPAAm。对于 PET 孔壁上厚度高达 80 nm 的干燥 PNIPAAm 层，观察到温度引起的溶胀/消溶胀比率类似于 3。通过用于引发剂固定的固相合成中的反应混合物的组成来降低刷接枝密度，导致溶胀/消溶胀比的增加。此外，通过 ATRP 合成的接枝 PNIPAAm 层的密度和温度响应与通过控制较少的光接枝在相同膜中获得的密度和温度响应进行了比较，导致接枝密度较低和接枝层密度梯度较大，因此溶胀/消溶胀比更高（> 15）。
A new method for surface-initiated atom transfer radical polymerization (ATRP) on the technical polymer poly(ethylene terephthalate) (PET) has been developed which allows controlling and estimating the layer thickness of the grafted polymer in the isocylindrical pores of track-etched membranes. After PET surface treatment by oxidative hydrolysis, the bromoalkyl initiator was immobilized on the PET surface in a two-step solid-phase reaction; the isoporous membrane structure was preserved, and the pore diameter was increased from 760 to 790 nm. Poly(N-isopropylacrylamide) (PNIPAAm) was grafted under ATRP conditions from a methanol/water mixture at room temperature. Both monomer concentration and reaction time could be used as parameters to adjust the degree of grafting. Effective grafted layer thickness and its response to temperature were estimated from pure water permeability. All data, especially the high polymer densities (0.37 g/cm(3)) in the swollen layers at 25 degrees C, indicate that grafted PNIPAAm with a "brush" structure has been achieved. For dry PNIPAAm layer thicknesses on the PET pore walls of up to 80 nm, a temperature-induced swelling/deswelling ratio of similar to 3 had been observed. Reduction of the brush grafting density, via composition of the reaction mixture used in solid-phase synthesis for initiator immobilization, led to an increase of that swelling/deswelling ratio. Further, density and temperature response of the grafted PNIPAAm layers synthesized via ATRP were compared with those obtained in the same membranes by less controlled photografting, leading to lower grafting density and larger gradients in grafted layer density and, consequently, much higher swelling/ deswelling ratios (> 15).