Grafting of Polymers from Clay Nanoparticles via In Situ Free Radical Surface-Initiated Polymerization: Monocationic versus Bicationic Initiators
Grafting of Polymers from Clay Nanoparticles via In Situ Free Radical Surface-Initiated Polymerization: Monocationic versus Bicationic Initiators
复制标题
通过原位自由基表面引发聚合从粘土纳米粒子接枝聚合物：单阳离子引发剂与双阳离子引发剂
作者：
Xiaowu Fan;Chuanjun Xia;R. Advíncula
比较了表面结合的单阳离子和双阳离子自由基引发剂在粘土纳米颗粒表面引发聚合（SIP）中的作用。作为使用两种不同的引发剂架构的结果，观察到分子量（MW），剥离的程度，和颗粒形态的不同属性。X射线衍射（XRD）结果表明，单阳离子引发剂插层后，粘土层间距增大，结构更加有序。IR、X射线光电子能谱和定性热重分析证实了两种引发剂的附着。XRD进一步表明，来自双阳离子引发剂的SIP产物保留了一些插层结构，而通过单阳离子引发剂的SIP实现了高度剥离的结构。因此，单阳离子引发剂产生了更高MW的聚合物。我们已经发现，良好分散的插层粘土颗粒和有效的单体扩散是进行成功的SIP和在实现高分子聚合的关键因素。
Surface-initiated polymerization (SIP) from clay nanoparticles was compared between surface-bound mono- and bicationic free radical initiators. Distinct properties in molecular weight (MW), extent of exfoliation, and particle morphology were observed as a consequence of using two different initiator architectures. X-ray diffraction (XRD) results showed that the clay intercalated with monocationic initiator has a larger d spacing and gave a more ordered structure. IR, X-ray photoelectron spectroscopy, and qualitative thermogravimetric analysis confirmed the attachment of both initiators. XRD further showed that the SIP product from the bicationic initiator retained some intercalated structure while a highly exfoliated structure is achieved by the SIP through the monocationic initiator. Consequently the monocationic initiator gave a higher MW polymer. We have found that well-dispersed intercalated clay particles and efficient monomer diffusion are crucial factors in performing a successful SIP and in achiev...