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The high molecular ladderlike polyhydrosilsesquioxane （LPHSQ） and its copolymer

ladderlike random copolymethylhydrosilsesquioxane （LR-PMHSQ） and ladderlike block copolymethylsilsesqui-oxane（LB-PMHSQ） have been synthesized by a preaminolysis reaction of the corresponding trichlorosilane with 1

4-phenylene diamine（PDA） then by hydrolysis and polycondensation reactions The thermographs of these polymers measured by DSC method indicate that these macromolecular backbones are very rigid as seen from the DSC curves which are almost horizontal from room temperature until 350

C

without noticeable glass transition. The content of Si—H group in the polymers can be regulated by changing the composition of the two copolymerized monomers. So the ladderlike polymers including its copolymers can be the useful precursors for the functional polymers

especially such as fishbone-like liquid crystalline polymers.