Yoshiro Sekine

Synthesis of tetramethyl-p-silphenylenesiloxanedimethylsiloxane triblock copolymer by employing living anionic polymerization

Dimethylsiloxane-tetramethyl-p-silphenylenesiloxane-dimethylsiloxane (DMS-TMPS-DMS) triblock copolymer was synthesized by employing living anionic polymerization of hexamethylcyclotrisiloxane (D3). Two synthetic methods were carried out for the polymerization. One of those methods was the anionic polymerization of D3 initiated at the silanolate anion which was prepared from the terminal hydroxyl group of silanol-terminated TMPS prepolymer by reaction with n-butyllithium (method 1). The other was the coupling reaction of vinyl-terminated TMPS prepolymer with hydrosilyl-terminated DMS prepolymer obtained from the anionic polymerization of D3 by using diphenylmethylsilanolate anion as initiator (method 2). In method 1, DMS contents of the copolymers ranged from 25.8 to 72.5 wt% and the values agreed with the ratio of D3 to TMPS prepolymer. The weight-average molecular weights ranged from 1.36×104 to 19.4×104 and were close to the predicted values calculated from the Mv of the TMPS prepolymer and the amount of D3 added. In the case of method 2, weight-average molecular weights ranged from 19.5×104 to 24.2×104. The high molecular weight copolymer could thus be obtained by method 2. Intrinsic viscosity values of the triblock copolymers agreed with calculated values obtained by considering the copolymer as a binary mixture of these homopolymers. Differential scanning calorimetry and thermogravimetry were carried out on the triblock copolymers. The equilibrium melting temperatures of each of the copolymers were very close to that of poly-TMPS (160°C). The glass transition temperature and heat of fusion were decreased as the DMS content was increased. The thermogravimetric curves for the copolymers indicated that the thermal stability of the triblock copolymer was intermediate between the DMS and TMPS homopolymers.

Syntheses and properties of tetramethyl-p-silphenylenesiloxanealkenylmethyl-siloxane copolymers and their derivatives

Abstract Tetramethyl -p- silphenylenesiloxane alkenylmethylsiloxane (TMPS/AMS) copolymers were snyhtesized from p -bis-dimethylhydroxysilylbenzene and a series of alkenylmethyldichlorosilanes as the starting materials. The alkenyl groups of the copolymers were vinyl, allyl, 2-(3-cyclohexenyl)ethyl, methacryloxypropyl and 3-bicycloheptenyl groups. The composition ranged from TMPS/AMS mole% ratio of 92 8 to 83 17 and the molecular weights were in the range 10 4 to 10 5 . These copolymers were confirmed to have two compositions, one a certain length of TMPS segment and the other an AMS monomer unit, and that they could form films on the basis of the crystallization character of the TMPS segment. The melting temperatures of these copolymers decreased as the TMPS mole content decreased and as the alkenyl group contents were increased. The epoxidation reactions of these copolymers with m -chloroperbenzoic acid were carried out and the proportions of conversions of the alkenyl groups into epoxy groups varied depending upon the types of alkenyl groups involved. Cyclic olefin groups such as the 2-(3-cyclohexenyl)ethyl or the 3-bicycloheptenyl group were more easily epoxidized than the vinyl or allyl groups. The TMPS/dimethylsiloxane (DMS) graft copolymer could also be synthesized by the reaction of TMPS/vinylmethylsiloxane copolymer with dimethylhydrosilyl-terminated DMS oligomer in the presence of chloroplatinic acid acting as the catalyst.

Tetramethyl-p-silphenylenesiloxanedimethylsiloxane block and graft copolymers as selective permeable membranes

We synthesized tetramethyl-p-silphenylenesiloxane (TMPS)dimethylsiloxane (DMS) copolymers as selective permeable membranes for oxygen and nitrogen, and investigated the relation between their permeability and selectivity and microstructure after preparing some membranes by a solvent casting method. First, we examined the permeability of TMPS/DMS block and graft copolymers (DMS segment length 100) using measurements of dynamic viscoelasticity, crystallinity, melting temperature (Tm) and glass transition temperature (Tg). These measurements showed the permeability to increase by mixing the TMPS and DMS phases, thus disturbing the fold crystallinity of the TMPS phase. Accordingly we investigated the permeability of block copolymers having shorter DMS segment lengths (DMS segment length 40,20). The membranes with mixed microstructures with shorter DMS segment lengths were successfully synthesized and showed excellent permeability. The selectivity also increased by shortening the DMS segment length, the selectivity being affected considerably by the TMPS phase. In particular, one of the copolymers containing 19% DMS (segment length 20) showed high permeability (PO2 = 2.3 × 10−8 cm3 cm/s cm2 cmHg) and high selectivity (α = 3.0).

Thermal and mechanical properties of tetramethyl-p-silphenylenesiloxanedimethylsiloxane block copolymer

Abstract Several kinds of tetramethyl -p- silphenylenesiloxane dimethylsiloxane (TMPS/DMS) block copolymers having various compositions and segment lengths were synthesized by the polycondensation of p -bis(dimethylhydroxysilyl)benzene and silanol-terminated DMS oligomers of different degrees of polymerization, which were 19, 43, 300, 380 and 540 DMS monomer units. The compositions ranged from TMPS/DMS wt% ratio of 100/0 to 24/76. For these copolymers, differential scanning calorimetry was carried out to determine the melting temperatures, the heat of fusion and the crystallinities. The melting temperatures and the crystallinities of the block copolymers were found to decrease as DMS contents were increased from 11 to 76 wt% and as DMS segment lengths were decreased from 540 to 19. The crystalline parts of TMPS segment would be increased according to the long TMPS sequences which were obtained from the copolymerizations by using DMS oligomers with high degrees of polymerization such as 300, 380 and 540. The stress-strain behaviour and the dynamic mechanical behaviour were also investigated for these copolymers. The tensile strength was decreased and the percentage elongation was increased with increasing DMS content and segment length. In the case of the copolymers for which the DMS contents remained constant at 26 wt%, two major transitions were observed at around −120° and −10°C for the copolymers having DMS block sizes of 300, 380 and 540. But for the copolymers having those of 19 and 43 the two transitions merged together at −50°C. The relaxations at −120°C corresponding to the glass transition of DMS component and those at −10°C are due to the amorphous TMPS phase which is separated from the DMS phase owing to the longer sequence length. The relaxation observed around −50°C is due to the shorter sequence length of TMPS in the main chain plus the presence of more flexible DMS component. It may be suggested that the long sequence length causes large domains of hard and soft phases which consist of TMPS and DMS blocks respectively.

Catalytic activity of poly(amino-organosiloxane)s

Abstract The poly(amino-organosiloxane)s (PAOS) form PAOS-Cu( ii ) complexes. The copper catalysed oxidation of ascorbate and hydroquinone by molecular oxygen was studied in the presence of PAOS. It was found that the addition of PAOS enhances the catalytic efficiency of Cu( ii ). The PAOS-Cu( ii ) catalysed reaction, unlike the Cu( ii ) catalysed reaction, becomes zero-order in the substrate concentration at relatively low concentration of substrate and exhibits Michaelis-Menten kinetics, which indicates the existence of a catalyst-substrate complex. This catalytic activity is similar to the poly( l -histidine)-Cu( ii ) catalysed reaction described by Pecht and Levitski. The specific effect of PAOS on the Cu( ii ) catalysed reactions is interpreted by the conformation of PAOS in aqueous solution, which is dependent on the flexibility and hydrophobicity of the PAOS main chain. In order to investigate the conformation of PAOS in aqueous solution, the decarboxylation of 6-nitrobenzisoxazole-3-carboxylate anion was studied, and it was found that the conformation of PAOS is easily controlled by altering the pH, the coordination to Cu( ii ) ions and the hydrophobicity of PAOS.

Synthesis of silica gels containing imidazole groups and their binding affinity for methyl orange in water

Abstract Silica gels containing imidazole groups or hexyl groups whose compositions are well controlled have been prepared. The imidazole group in the gel was quaternized with C 4 H 9 Br, C 6 H 13 Br or C 12 H 25 Br to obtain gels that are charged and have an alkyl chain. Their binding affinities for methyl orange in water were then investigated. We aimed to clarify the relation between the structure of the gel and its binding behaviour for small molecules in water. So the binding affinities of the unquaternized and quaternized gels were compared for methyl orange in water at various temperatures and we obtained the thermodynamic parameters for this binding. It was found that in silica gel the alkyl chain that is bound chemically to the charged site is very efficient for binding the dye in water.

Studies on Molecular Weight Distribution of Chlorinated Polycarbonate with Turbidimetric Precipitation Titration Method

Morey-Tamblyn の沈殿濁度滴定法 (塩化メチレン-シクロヘキサン系) を用い, 前報で合成した塩素化ポリカーボネートの分子量分布について検討した。検量線の作成には重合法の異なった二種類の共重合物 (TT-BB, TB-TB) と単独重合物 (TT-TT) の分別試料を用い, γ=k log c+f(M) から k と M, k と f(M) の関係を求めた。TT-BB : -k=O.0539 M-0.111(M 15000～100000), TT-TT:-k=3.652 k log M-0.498(M 10000～60000) となり k は Mによって変わる。濁度法と逐次分別沈殿法との比較, 等量混合物の検討はいずれもよい一致を示した。重合の経時変化から求めた分子量分布曲線は重合条件によって多峰性となるが, 条件の適切なものは計算から求めた Schulz-Zimm 型の分布曲線とよい一致を示し, 前報の検討結果が裏付けされた。最終時の重合体の分布曲線から算出した変動係数 δ=(Mz/Mw-1)1/2 は TT-BB:0.5～0.6,TB-TB:0.3となり重合法により差異が認められた。第二ビリアル係数は BPA からのポリカーボネートより小さい。

Process for Producing Tetrachloro-Bisphenol A (TCBPA) with Aluminum Chloride Catalyst

前報の塩化アルミニウム触媒による研究結果に基づいて, 四塩化ピスフェノールA (TCBPA) の工業的製造法を検討するため, 氷酢酸を溶媒とし塩素化を行ない母液を循環再使用する半連続操作法について, 不純物の生成条件, 精製法について調べた。ビスフェノールA (BPA) の初回仕込み濃度 10～15%, 反応温度 32±0.5℃, 塩素/BPA mol 比 4.2～4.6 で再循環させた結果, 収率は 80% であった。母液中の水分量が使用回数に最も著しい影響を与える。5～6% までは初回の TCBPA の純度と差はないが, それ以上になると著しい低下が見られる。前報の手法に従い算出した相対速度定数からは, BPAの消失速度, ジクロル-BPA 生成速度は大きく, トリクロル-BPA, TCBPA の速度は小さくなり, 反応中間物と TCBPA の分離が困難となることがわかった。また抑制された状態でのトリクロル-BPA, TCBPA生成速度は逐次大きくなって, 前報の無触媒における典型的な逐次反応の様相を呈し, 過塩素化物生成速度も大きくなる。塩素の過剰の吹込みは, 過塩素化物の混入となって再循環使用が不可能となる。TCBPAの精製には冷却下カキマゼによる晶析法と水洗塔による方法の併用が有効であった。

Interfacial Copolycondensation of Bisphenol A and Tetrachloro-Bisphenol A by the Successive Addition Process

モノマーの逐次添加方式により, 化学的に均一組成の共重合体を合成する方法の検討を行なった。モノマーの添加方法は反応の初期に BPA を少なく, TCBPA を多く, 後期に BPA のみを添加する添加曲線 I, II (モノマー比 50/50) に従った。反応条件は前報の検討結果に基づいた。重合物は収率 80～90%, M 18000～72000, Cl% 20～22 (計算値 21.94%) で合成され, 再現性もよい。勾配の急な I の方が好結果となり, メタノールの添加による分子量の調節, モノマー組成比変化 75/25, 25/75 からも目的の共重合体が得られた。分別物の塩素 % と M の関係から組成の均一性が示され, 熱分解曲線から, 不均一のものと明らかに差異が認められた。皮膜の弾性率も向上する。ホスゲン化反応におけるCl%の経時変化はビニル重合の共重合組成式 [m1]/[m2]=[M1]/[M2]・r1[M1]+[M2]/r2[M2]+[M1](r1,r2前報参照) から計算した結果とほぼ一致し, 不一致の部分は前報のホスゲン化速度比の考慮により補正される。重縮合では乳化剤量によるオリゴマーの拡散の防害と, BPA が多い配合での触媒量による分解が M の生長に大きい影響を持つ。

Effect of Various Factors in Interfacial Copolycondensation of Bisphenol A and Tetrachloro-Bisphenol A

モノマーの性質, 単独重合条件の比較および TCBPA のカセイソーダ水溶液と BPA のビスクロロホルメートの反応から共重合条件を調べた。TCBPA の重合条件を BPA と比較すると, ホスゲン化速度および縮合速度が小さいためホスゲン化時間 (6～8時間) を長くする。TCBPA のクロロホルメート基は加水分解され易いため pH9.6～10.0 で行なう。界面での接触をよくするため乳化剤 (非イオン性) 0.25～0.50% 添加する。触媒 (TMBAC) をホスゲン化に0.6%,重縮合に2～3%添加(BPAでは分解)する。これらの点に留意し, 収率 80～85%, M約3万の重合体が合成された。分子量分布の経時変化を濁度法より求め, 定性的に Schulz-Zimm 型の分布曲線と類似し, 条件の適切さが示された。共重縮合は pH12.0, 触媒量 1% (2%で分解) 乳化剤なしで行ない, 初期に塩素%の低下を伴ないつつオリゴマーが形成され, オリゴマー同志が反応して M 約 10 万塩素 % 12～13.5 (計算値21.94%) の重合物となり, 目的組成の共重合体とするには触媒量, pH による加水分解を避ける必要がある。モノマー反応性 比 r1=k11/k12=1.87, r2=k22/k21=O.5 (M1 : BPA, M2 : TCBPA) から r1・r2≒1 となり, ビニル重合のモノマー逐次添加方法と上述の反応条件の考慮により, 化学的に均一組成の共重合体の合成が可能である。