Silsesquioxanes. Part II. Polysilsesquioxanes
Polimery 2001, No 9, 582
SummaryA review with 90 references covering methods used to prepare polyphenylsilsesquioxanes (PPSQ) and ladder-structured polymethylsilsesquioxanes (PMSQ) (formula I), viz., (i) three- or two-step hydrolytic polycondensations of trifunctional silanes RSiX3 (R = alkyl, aryl; X = Cl, OR', OAc); (ii) stepwise coupling polymerization of RSiX3; (iii) polymerization of polyhedral silsesquioxanes. Methods to prepare insoluble globular spherical PMSQ and bridged polysilsesquioxanes (formulas III and IV) are als o reviewed. Evidence is adduced for the ladder structure of polysilsesquioxanes (formulas V and VI; Table 1). Selected physicochemical property data and thermal stability data are given. Principal polysilsesquioxane application trends are characterized.