Study of the Steric Tacticity of Novel Soluble Ladderlike Poly(phenylsilsesquioxane) Prepared by Stepwise Coupling Polymerization

Abstract

A novel kind of soluble ladderlike poly(phenylsilsesquioxane) (LPPS) was prepared by stepwise coupling polymerization. Various techniques, such as fluorescence spectroscopy, X‐ray diffraction (XRD), molecular simulation and calculation, were combined to indicate that the steric structure in LPPS was predominantly cis‐isotactic. It is anticipated that stepwise coupling polymerization is a useful synthetic method for preparing ladderlike poly(silsesquioxane)s with cis‐isotactic structure, which have potential applications as functional polymers or as precursors for the further synthesis of novel advanced polymers.

Macroporous materials by self-assembly of linear oligo(phenylsilsesquioxanes).

“…Hindered rotation about siloxane bonds in the double silsesquioxane chain of poly(phenylsilsesquioxanes) [48] prevents its folding and coil aggregation in solution that could result in fluorescence quenching. Fluorescence studies were thus carried out at room temperature for the prepared Ph-LPSQ (sample 1a, Table 1) both in solution and as micelles suspended in hexanes.…”

“…The preferential activation of side silanols in linear oligomers in the twostep, acid-base catalyzed sol-gel process, as well as steric and electronic factors caused by side phenyl groups, result in formation of Ph-LPSQ of ladderlike structure. Obviously, the silsesquioxane backbone of the obtained products is statistically more branched than that prepared by stepwise coupling polycondensation method [48]. -4 ) on the structure of product was studied ( Table 1).…”

“…Regularity of the structure of Ph-LPSQ chains cannot be proved by a MALDI spectrum alone. Wide angle X-ray diffraction (WAXS) data collected for the prepared materials ( Figure 6) were compared with the diffraction pattern of cis-isotactic Ph-LPSQ obtained following the reported stepwise coupling polycondensation procedure [48]. WAXS diffractograms of both amorphous polymers are almost identical and suggest the presence of ladder segments (d 1 ).…”

“…It is expected that such structured particles could possibly find an application as precursors to ceramic silicon-oxycarbide microspheres with high C/Si ratio, macroporous templates and chromatographic stationary phases. Model linear Ph-LPSQ of regular structure was prepared as earlier reported [48]. Solvents were purified according to literature procedures [49].…”

Alkali-Metal-Directed Hydrolytic Condensation of 3-Mercaptopropyltrimethoxysilane

“…Several synthetic methods were proposed for the preparation of ladder-like polysilsesquioxanes, including step wise coupling polymerization [3][4][5][6][7] or hydrolytic condensation of trifunctional organosilanes [2,[8][9][10]. However, the most promising method for the preparation of defect-free LPSQs is hydrolytic condensation of monomers containing cyclic siloxane units [11][12][13][14][15][16][17][18][19].…”