Trichlorophenylsilane Research Articles

One-Pot Synthesis of Oligo-Ladder Phenylsilsesquioxanes via Pyridine–Silicon Adduct Formation at Aqueous–Organic Liquid Boundary

Three kinds of oligo-ladder polyphenylsilsesquioxanes were synthesized by two unique methods through the aqueous–organic boundary reaction via octahedrally-coordinated pyridine–silicon adduct PhSiCl3(Py)2, which is formed from trichlorophenylsilane (TCP) monomer and pyridine in n-propyl acetate. When two equivalent pyridines to TCP were used, SQ polymer-1 was formed as a viscous solid, which was recrystallized in n-hexane to obtain SQ polymer-2B. When an excess pyridine was used (pyridine/Si = 10), SQ polymer-2A was directly obtained as a white solid. MALDI–TOF/TOF–MS, FT-IR and 29SiNMR clearly shows that the “Ladder” structure of SQ polymers is dominant in both methods. It was shown that in this one-pot synthesis, SQ polymer structure was controlled by pyridine amount. Furthermore, MO simulation of pyridine adduct formation (PhSiCl3(Py)2) supports the hydrolysis pathway for synthesis as well as the “Ladder” structure formation. Finally, it was also suggested that the hydrolysis reaction occurred in a stepwise manner.

Synthesis of silicon-containing monomers with aldehyde groups

Silicon-containing monomers with different functional groups are used in the synthesis of heat and corrosion resistant polymers, as well as modifiers for various polymers to improve their operational characteristics [1–3]. The goal of the present work was to synthesize silicon-containing monomers functionalized with aldehyde groups, which may be used for the preparation of polymers with enhanced heat and frost resistance and tensile strength as compared to carboxycontaining polymers [3]. The procedure developed by us for the synthesis of such monomers is based on the reaction of trichloro(phenyl)silane with hydroxy aldehydes. The reaction of trichloro(phenyl)silane with β-hydroxybutyraldehyde gave tris-butanal I (Scheme 1). alcohols, ketones, and ethers and insoluble in aliphatic hydrocarbons and water.

Reaction of Germanium Tetrachloride with Chloro(phenyl)silanes in the Presence of Aluminum Chloride

The effect of the quantity of aluminum chloride on the direction and depth of reaction of germanium tetrachloride with chloro(phenyl)silanes of the general formula PhnSiCl4−n (n = 1 – 3) was studied to show that radical exchange between germanium and silicon is initiated only if the mixture contains no less than 2.5–5 wt % of aluminum chloride. With trichloro(phenyl)silane, the radical exchange is initiated at 5 wt % of aluminum chloride and results in exclusive formation of trichloro(phenyl)germane. The reactions of GeCl4 with dichlorodiphenylsilane and chlorotriphenylsilane in the presence of 2.5–7.5 wt % of aluminum chloride give dichlorodiphenylgermane as the major product, and at AlCl3 concentrations of above 10 wt % the major product becomes to be trichloro(phenyl)germane.

Formation of Stable Nanoparticles of Poly(phenyl/methylsilsesquioxane) in Aqueous Solution

Nanoparticles of poly(phenyl/methylsilsesquioxane) (PPMSQ) were prepared by emulsion polymerization of the co-hydrolysate that had been formed from a mixture of trichlorophenylsilane (TCP) and trichloromethylsilane (TCM) in aqueous solution. The average size of the resultant particles was controlled from 30 to 250 nm in diameter by changing the initial concentration of the co-hydrolysate and the amount of the emulsifier added. The PPMSQ formed from the hydrolysate of TCP/TCM had a high cross-linking density, being insoluble and stable in nature. The 1 H NMR spectrum of the co-hydrolysate revealed that both the primary hydrolysates of TCP and TCM are involved in the fast co-polycondensation to afford meta-stable water-soluble oligomers having many silanol groups. These oligomers are allowed to react with each other to form the nanoparticles with the aid of emulsifier.

Preparation of Nano-Particles of Poly(phenylsilsesquioxane)s by Emulsion Polycondensation of Phenylsilanetriol Formed in Aqueous Solution

Spherical nano-particles of Poly(phenylsilsesquioxane) (PPSQ) were prepared by emulsion polymerization of phenylsilanetriol (PST) that had been formed in aqueous solution after hydrolysis of trichlorophenylsilane (TCP). The average size of the resultant particles was controlled from 30 nm to 110 nm in diameter by changing the amount of the emulsifier added to the solution. The PPSQ forming the particles was low molecular weight oligomer, consisting of silanol groups that can be utilized as functional groups for further chemical modification.

Synthesis and Polycondensation of a Cyclic Oligo(phenylsilsesquioxane) as a Model Reaction for the Formation of Poly(silsesquioxane) Ladder Polymer

A tetracyclo(phenylsilsesquioxane) (T4) was first synthesized by the oligomerization of the low molecular weight hydrolysate of trichlorophenylsilane (TCP) by catalysis of the weak base, NaHCO3, followed by KOH-catalyzed polycondensation in toluene to form poly(phenylsilsesquioxane) (PPQS). The rate of polycondensation of T4 was much slower than that of direct polycondensation of the TCP hydrolysate under identical conditions. The molecular weight of the former product (Mn=35800) was significantly lower than that of the latter product (Mn=110000). X-Ray scatterings of the PPQS prepared by both processes were slightly different, probably due to the difference in structural regularity or branched structure. These data suggest that the polycondensations of T4 and the TCP hydrolysate should be driven through different reaction mechanisms, although the formation of the double strand ladder chain in the produced PPQS should be common to both.

Structural Regularity of Poly(phenylsilsesquioxane) Prepared from the Low Molecular Weight Hydrolysates of Trichlorophenylsilane

Various hydrolysates of trichlorophenylsilane (TCP) and their polycondensates were reacted with trichlorosilane for capping the silanol groups formed in defect points of the ladder structure. The 1H NMR spectra of the capping products obtained showed several signals due to the Me3Si groups in different environment. Particularly, the polycondensate prepared from the TCP hydrolysate having higher molecular weight showed both sharp and broad Me3Si signals, suggesting a core-shell type branched structure. No Me3Si signal was shown in the polycondensate prepared from the hydrolysate with low molecular weight, supporting an almost perfect ladder structure with few bonding defects. The wide angle X-ray scattering (WAXS) of this polycondensate showed clear Debye-Scherrer rings due to the crystallization of the polymer chains having the regular ladder structure. The structural regularity of this polycondensate was also supported by the 29Si NMR spectrum. This polymer, having a stable double-strand structure, was found to undergo no base-catalyzed depolymerization in solution. A stepwise polycondensation is proposed for the formation of the ladder polymer in which the trivalent (T0: PhSi(O−)3) or divalent (T1: PhSi(OSi)(O−)2) siloxyl units should be involved in the reaction, leaving the monovalent siloxyl (T2: PhSi(OSi)2(O−)) units unreacted.

A New Formation Process of Poly(phenylsilsesquioxane) in the Hydrolytic Polycondensation of Trichlorophenylsilane. Isolation of Low Molecular Weight Hydrolysates to Form High Molecular Weight Polymers at Mild Reaction Conditions

Trichlorophenylsilane (TCP) was hydrolyzed in an toluene/water heterogeneous solvent system, and a low molecular weight hydrolysate with simple structure was isolated from the aqueous solution while a high molecular weight hydrolysate with complicated structure was isolated from the toluene layer. When this hydrolysis was conducted strictly at 0°C, the primary hydrolysate consisting mainly of phenylsilanetriol (PST) could be crystallized out from the aqueous layer. When the low molecular weight hydrolysate obtained from the aqueous layer was subjected to the KOH-catalyzed polycondensation in refluxing toluene, poly(phenylsilsesquioxane) (PPQS) with a highly ordered ladder structure could be obtained. Its molecular weight increased with decreasing molecular weight of the initial hydrolysate, and its silanol content oppositely decreased with it. Since this polycondensation proceeded stepwise, it has been considered that intramolecular cyclization is favored in the first condensation of the low molecular weight hydrolysate and that the resultant higher oligomers are then connected into high polymer with ladder structure by the silanol coupling. The molecular weight of PPQS finally obtained reached 120 kDa.