SYNTHESIS AND CHARACTERIZATION OF A NOVEL REACTIVE LADDER-LIKE POLYSILSESQUIOXANE WITH LATERAL BROMOPHENYL GROUPS

A novel soluble, reactive ladder-like polysilsesquioxane (L) with lateral bromophenyl groups was synthesized successfully by stepwise coupling polymerization (SCP) method including preaminolysis, hydrolysis and polycondensation steps. The monomer 3-trichlorosilylpropoxy-4-bromobenzene (M) was first prepared via hydrosilylation reaction catalyzed by dicyclopentadienylplatinum dichloride (Cp2PtCl2). The title polymer (L) was characterized by 1H-NMR, 29Si-NMR, FTIR, X-ray diffraction (XRD), DSC and vapor pressure osmometry (VPO). The experimental results indicate that the polymer (L) possesses a typical ladder-like structure.

CONCERTED H-BONDING TEMPLATE SYNTHESIS OF AN ORDERED LADDER POLYSILSESQUIOXANE

A novel soluble regular ladder poly（benzoyl-3-aminopropyl） silsesquioxane （LPBAS） was facilely prepared under effective assistance of concerted H-bonding self-assembly of amido groups of side chains and silanol groups, respectively, of a new template monomer [1,3-bis（benzoyl-3-aminopropyl）-1,1,3,3-tetraethoxydisiloxane] （M）. The ordered ladder structure of LPBAS is manifested in： （1） the presence of two Bragg peaks representing the ladder width （d） and ladder thickness （t） in X-ray diffraction （XRD） pattern; （2） narrow base-line width （w = 6） of resonance absorption for -CH2SiO3/2 moiety in 29Si-NMR and （3） high glass transition temperature Tg = 1 12℃ in differential scanning calorimetry （DSC） analysis.

SYNTHESIS OF HIGH THERMOSTABLE SILICONE GELS CONSTRUCTED WITH LADDERLIKE POLYSILSESQUIOXANES

Heat-resistant silicone gels were synthesized by replacing the single main chain polymethylhydrosiloxane with reactive ladderlike polyhydrosilsesquioxane copolymers. Because of the interaction between polydimethylsiloxane chains and the ladderlike polysilsesquioxanes chains, the cyclization of the polydimethylsiloxane chains is hindered. The high thermal stability of the ladderlike polymers can improve the thermal stability of the silicone gels without sacrificing their good comprehensive properties.

SYNTHESIS AND CHARACTERIZATION OF A SOLUBLE LADDERLIKE POLYSILSESQUIOXANE CONTAINING REACTIVE ESTER GROUPS

A novel soluble ladderlike polysilsesquioxane containing reactive ester groups (Ester-T) was synthesized for the first time by stepwise coupling polymerization including preammonolysis, controlled hydrolysis and polycondensation. The monomer, 3-trichlorosilylpropoxy 4-acetoxybenzoate (M), was synthesized by hydrosilylation of allyloxy 4-acetoxybenzoate with trichlorosilane in the presence of dicyclopentadienylplatinum (II) chloride (Cp2PtCl2) catalyst. Combination of FTIR, H-1-NMR, C-13-NMR, Si-29-NMR, XRD, DSC, TGA and VPO methods was used to demonstrate that the polymer obtained has an ordered ladderlike structure. The synthesized Ester-T may have promising applications as a precursor of advanced functional polymers.

SYNTHESIS AND CHARACTERIZATION OF AMINO FUNCTIONALIZED LADDER-LIKE POLYSILSESQUIOXANES AND THEIR HYBRID FILMS WITH POLYIMIDE

Ladder-like polysilsesquioxanes （LPSQs） with different amino contents have been synthesized by controlling of the dosage of Pd/C catalyst. The concentration and activity of amino groups were investigated by Fourier transform infrared spectroscopy. Polyimide （PI）/LPSQ hybrid films have been prepared by incorporating of the obtained LPSQs with different amino contents into PI matrix, respectively. The interfacial interactions between PI matrix and LPSQ were studied with scanning electron microscopy and X-ray photoelectron spectroscopy, meanwhile the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests. The results indicate that the functionality of LPSQ has great effects on the interfacial interactions and the properties of hybrid films. With the increase of amino content, both the interracial interactions and the cross-linking density of hybrids enhanced, which results in the decline of surface silicon concentration, increase of Young＇s modulus and drop of elongation at break. Excessive amino content makes the hybrid films brittle and leads to incomplete imidization.

SYNTHESIS AND-CHARACTERIZATION OF THE SOLUBLE, HIGH MOLECULAR WEIGHT AND LADDERLIKE POLYHYDROSILSESQUIOXANE AND ITS COPOLYMERS

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;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.

Synthesis and Characterization of Novel Organic/Inorganic Hybrid Polymers Containing Polyhedral Oligosilsesquioxanes

Hybrid polymers, poly(vinyl pyrrolidone-co-isobutyl styryl polyhedral oligomeric silsesquioxanes)s (PVP-POSS) were synthesized by one step polymerization and characterized using GPC and DSC. Addition of POSS significantly increases the Tg of polyvinylpyrrolidone at a fair high POSS content and obtained high molecular weight polymers with very narrow molecular distribution. The POSS content in the resulted hybrids can be controlled by varying the POSS feed ratio.