Polysiloxanes are industrially important silicon-based polymeric materials which cannot be replaced by carbon-based ones. In this area, synthesis of well-defined functional poly(dimethyl siloxane) (PDMS) with nonlinear macromolecular architectures is indispensable for finding next-generation applications. Here we report the synthesis of cyclic PDMS (C) with photocleavable and reformable hexaarylbiimidazole (HABI)-derived covalent bonds in the main chain from triphenylimidadole (lophine) end-functionalized monodisperse linear precursors (Ls). Interestingly, an end-to-end cyclization reaction of L with the concentration (10 mg/mL) much higher than that of a typical concentration (~0.1 mg/mL) dominantly produced unimolecularly cyclized product. Moreover, photoirradiation to C under a solvent-free condition, molecular weight increased despite the physical state of C was solid.

聚硅氧烷是工业上重要的硅基聚合物材料，不能被碳基材料替代。在这一领域，具有非线性大分子结构的功能明确的聚二甲基硅氧烷（PDMS）的合成对于寻找下一代应用是必不可少的。在这里，我们报道了在主链中由三苯基咪唑（Lophine）末端官能化的单分散线性前体（L s）合成具有光可裂解和可重整的六芳基联咪唑（HABI）衍生的共价键的环状PDMS（C）。有趣的是，L的端到端环化反应浓度（10 mg / mL）远远高于典型浓度（〜0.1 mg / mL）占主导地位的单分子环化产物。此外，在无溶剂条件下对C进行光照射，尽管C的物理状态为固体，但分子量增加。