星形聚硅氧烷的热稳定性研究和结构表征

含六苯基环三硅氮烷 (P3N)的聚硅氧烷的低温性能与普通聚硅氧烷相当 .35 0℃ ,封闭氮气中老化2 4h后 ,含P3N 聚硅氧烷的热失重比普通聚硅氧烷低 4～ 10倍 ,随聚合物含氮量增加 ,其失重呈下降趋势 ,最低失重为 1 1% .六苯基环三硅氮烷三锂盐 (P3NLi)引发环硅氧烷聚合得到的含P3N 聚硅氧烷的2 9Si NMR谱、IR谱和分子量 (GPC)与特性粘数的关系证明其具有星形结构

STUDIES ON THE THERMAL STABILITY AND STRUCTURAL CHARACTERIZATION OF STAR POLYSILOXANE

The low temperature properties of polydimethylsiloxane(PDMS+N) containing hexaphenylcyclotrisilazane(P-3+N) and the commerical PDMS were comparable according to their DSC data.The glass transition temperature of PDMS+N was -120℃.After heating for 24 hours at 350℃ in a sealed N-2 system,the weight loss of PDMS+N was 4～10 times lower as that of the commericial PDMS,and decreased with increasing its nitrogen content,thus,its least weight loss was 1.1%.The 29 Si|NMR spectra,IR spectra and the relationship between the molecular weight (by GPC) and limiting viscosity number of PDMS+N,which was synthesized through the polymerization of cyclosiloxane with trilithium salt (P 3 NLi ) of hexaphenylcyclotrisilazane as an initiator,demonstrated that PDMS+N was a star polymer.Also, N,N,N| trimethylhexaphenylcyclotrisilazane,which was prepared quantitatively through the reaction of P-3 NLi and MeI in the polar solvent,was characterized by the elemental analysis, 1H|NMR and 29 Si|NMR spectra,IR spectra.The star polymer nature of PDMS+N was also proved indirectly by the characterization of N,N,N| trimethylhexaphenylcyclotrisilazane.