H-bonding template-directed synthesis of a complete m-PDA-bridged ladder polyhydrosiloxane （OLPHS）

A highly ordered m-phenylenediimino-bridged ladder polyhydrosiloxane (abbr. OLPHS) with Mn = 1.24 104 was synthesized under assistance of H-bonding template constructed from imino H-bonding, N(Si)-H N(Si)-H, via a modified process of stoichiometric hydrolysis and dehydrochlorination condensation reaction between Si–Cl and Si–OH bonds. The complete ladder structure of OLPHS has been confirmed by the following three data. Two characteristic Bragg’s peaks representing the ladder width (w =0:94 nm) and ladder thickness (t = 0.42 nm) were observed in XRD analysis, which are consistent with those cal- culated by molecular simulation. The very sharp absorption with a small half-peak width ew1=2=0:5 ppmT for [(–HN)HSiO2/2]n moiety of OLPHS in 29Si NMR spectrum indicated presence of the complete ladder structure. As collateral evidence, a higher glass transition temperature (Tg = 105 8C) is also recorded in the DSC measurement, implying the high stiffness of ladder chain of OLPHS.