An ordered reactive ladderlike polyhydrosilsesquioxane (H-T) was successfully synthesized via a modified “stepwise coupling polymerization” process

which included two improvements in synthetic method．First

dehydrochlorination polycondensation between Si—OH and Si—Cl groups during polycondensation reaction is employed instead of the dehydration between Si—OH groups used before

which improves the H-bonding template effect of the bridged-phenylene diamine．Meanwhile

trimethylchlorosilane is used to block the terminal silanol groups

avoiding the further intermolecular crosslinking of the phenylene diamine-bridged ladderlike macromolecular intermediates．Consequently

the regularity of H-T has been improved

and compared with a very low Tg(-123℃) of the single-chained polydimethylsiloxane

a significantly higher Tg(117.0℃) of H-T in DSC measurement confirms that the ordered reactive H-T macromolecule possesses comparatively stiff main chain．Above all

the peak of HSiO3/2 (-84.8) with the baseline width (Δ) of about 5 in 29Si-NMR spectrum which is much narrower than that of the polysilsesquioxane (Δ=8～10) prepared by the usual dehydration condensation method shows that the regularity of H-T is obviously improved．Furthermore

H-T is the first soluble

reactive and purely inorganic ladderlike macromolecule

which can be grafted through hydrosilylation reaction and others to generate functional LPSs with different side groups.