Functionalized Silsesquioxane Preparation Of Polymer Composites

Octa(Υ-chloropropyl)silsesquioxane(OCP-POSS)was prepared by completely hydrolysis and condensation ofΥ-chloropropyltrimethoxysilane in the presence of concentrated hydrochloric acid as the catalyst.TriSilanolPhenyl-POSS(C₄₂H₃₈O₁₂Si₇) (POSS-triol)was prepared by base catalyzed cleavage of octaphenyl-silsesquioxane(OPS). And both were characterized by Nuclear Magnetic Resonance(NMR),Fourier transform infrared(FT-IR)spectrometer,Element Analysis(EA)and X-ray diffraction(XRD).With OCP-POSS as the initiator,copper(I)chloride/2,2'-Bipyridine as the catalyst, poly(methylmethacrylate)(PMMA)was prepared via atom transfer radical polymerization in solution.The molecular weight and its distribution were determined by gel permeation chromatography(GPC).The results show that the PMMA prepared via ATRP has very narrow molecular weight distribution.The polydispersity of PMMA may reach 1.19.And differential scanning calorimetry results show that the prepared PMMA has higher glass transition temperature(T_g)than that of the liner polymer by about 20℃.Curing process of Cyanate Ester(CE),CE/OCP-POSS 100/10 and CE/POSS-triol 100/10 composites were measured by non-isothermal DSC at different scanning rates.The apparent activation energies(E_a)and reaction order(n)of the cure systems were obtained by Kissinger equation and Flynn-Wall-Ozawa method.The results indicate that CE/POSS-triol composite has lower E_a but bigger n than pure CE.However,both E_a and n of CE/OCP-POSS composite are bigger than pure CEo The curing processes of the systems were determined by extrapolation method of T-βcurves.The composite of CE/POSS and CE/EP/POSS were prepared in situ.The composites containing different content of different POSS were characterized by dynamic mechanical thermal analysis(DMTA),thermogravimetric analysis(TGA),FT-IR and scanning electron microscopy(SEM).The results show that both of OCP-POSS and POSS-triol were throughly dispersed into the resin.And the loading of OCP-POSS can reduce both the storage modulus and T_g of CE and CE/EP composite.In contrary to OCP-POSS,the incorparation of POSS-triol into CE and CE/EP resin result in higher storage modulus and T_g.The thermal stability of the composites were raised after the addition of OCP-POSS or POSS-triol.