Department of Chemistry, Istanbul Technical University, 34469 Maslak, Turkey.
Molecules. 2023 Jan 29;28(3):1299. doi: 10.3390/molecules28031299.
Photochemical techniques have recently been revitalized as they can readily be adapted to different polymerization modes to yield a wide range of complex macromolecular structures. However, the implementation of the photoinduced cationic methods in the polymerization of cyclic siloxane monomers has scarcely been investigated. Octamethylcyclotetrasiloxane (D4) is an important monomer for the synthesis of polydimethylsiloxane (PDMS) and its copolymers. In this study, the cationic ring-opening polymerization (ROP) of D4, initiated by diphenyl iodonium hexafluorophosphate (DPI), has been studied. Both direct and indirect initiating systems acting at broad wavelength using benzophenone and pyrene were investigated. In both systems, photochemically generated protonic acids and silylium cations are responsible for the polymerization. The kinetics of the polymerization are followed by viscosimetry and GPC analyses. The reported approach may overcome the problems associated with conventional methods and therefore represents industrial importance for the fabrication of polysiloxanes.
光化学技术最近得到了复兴，因为它们可以很容易地适应不同的聚合模式，从而产生广泛的复杂大分子结构。然而，光诱导阳离子方法在环状硅氧烷单体聚合中的应用几乎没有被研究过。八甲基环四硅氧烷（D4）是合成聚二甲基硅氧烷（PDMS）及其共聚物的重要单体。在这项研究中，研究了二苯基碘𬭩六氟磷酸盐（DPI）引发的 D4 的阳离子开环聚合（ROP）。使用苯并二苯酮和芘的直接和间接引发体系在宽波长范围内起作用。在这两个体系中，聚合反应由光化学产生的质子酸和硅鎓阳离子引发。聚合动力学通过粘度和 GPC 分析进行跟踪。所报道的方法可以克服与传统方法相关的问题，因此对于制造聚硅氧烷具有工业重要性。
