Lin Xi, Huang Rong, Ulbricht Mathias
Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany.
J Mater Chem B. 2016 Feb 7;4(5):867-879. doi: 10.1039/c5tb02368h. Epub 2016 Jan 7.
Stimuli-responsive separation membranes with tunable molecular scale pore size, which are desirable for on-demand sieving of targeted macromolecules, have attracted increasing attention in recent years. In this study, novel magneto-hydrogel pore-filled composite membranes with excellent magneto-responsivity and tunability for molecular sieving have been developed. Such membranes comprising magnetic nanoparticles (MNPs) as localized heater which can be excited by high frequency alternating magnetic field (AMF), poly(N-isopropylacrylamide) (PNIPAAm) hydrogel network as the sieving medium and actuator, and polyethylene terephthalate (PET) track-etched membrane as robust support, have been prepared via in situ reactive pore-filling functionalization. Rheological study has been carried out first to investigate the influence of MNPs and initiation methods on gelation kinetics and microstructure of the MNP-PNIPAAm composite hydrogels, and to identify proper conditions for further pore-filling functionalization. Then AMF distribution of chosen field condition and its heating effectiveness for MNPs and MNP-PNIPAMm composite hydrogel were studied. Pre-functionalization of the PET membranes with linear polymer chains with different composition were compared with respect to their effects for achieving desired MNP loading and fixation of the hydrogel network in the pores. At last, in situ reactive pore-filling functionalization was carried out to immobilize robust magneto-hydrogel in the pores of the membranes. Conditions were investigated and optimized to obtain functionalized membranes with high MNP loading and suited PNIPAM network properties, i.e. good stimuli-responsivity and sieving in the ultrafiltration range. The excellent thermo- and magneto-responsivity of obtained pore-filled membranes was proved by its large and reversible change of water permeability in response to switching on and off the AMF. Finally, it was demonstrated by filtration of dextrans with different molecular weights that the membranes had ultrafiltration properties and that large changes of their molecular sieving performance could be obtained by "remote control" with the external AMF.
具有可调分子尺度孔径的刺激响应分离膜，因其可按需筛分目标大分子而受到近年来越来越多的关注。在本研究中，已开发出具有优异磁响应性和分子筛分可调性的新型磁水凝胶孔填充复合膜。这种膜由作为局部加热器的磁性纳米颗粒（MNPs）组成，其可被高频交变磁场（AMF）激发；聚（N-异丙基丙烯酰胺）（PNIPAAm）水凝胶网络作为筛分介质和致动器；以及聚对苯二甲酸乙二酯（PET）径迹蚀刻膜作为坚固支撑体，通过原位反应性孔填充功能化制备而成。首先进行了流变学研究，以研究MNPs和引发方法对MNP-PNIPAAm复合水凝胶的凝胶动力学和微观结构的影响，并确定进一步进行孔填充功能化的合适条件。然后研究了所选场条件下的AMF分布及其对MNPs和MNP-PNIPAMm复合水凝胶的加热效果。比较了用不同组成的线性聚合物链对PET膜进行预功能化对实现所需MNP负载和水凝胶网络在孔中的固定的效果。最后，进行原位反应性孔填充功能化，将坚固的磁水凝胶固定在膜的孔中。研究并优化了条件，以获得具有高MNP负载和合适PNIPAM网络性能（即良好的刺激响应性和超滤范围内的筛分性能）的功能化膜。所获得的孔填充膜优异的热响应和磁响应性通过其在AMF开启和关闭时水渗透性的大幅可逆变化得到证明。最后，通过对不同分子量的葡聚糖进行过滤证明，该膜具有超滤性能，并且通过外部AMF“远程控制”可使其分子筛分性能发生大幅变化。
