The Effect of Weight Fraction of H-PDMS on the Latex Membrane and the Stability of Composite Emulsion of H-PDMS/Acrylate

High hydrogen-containing polymethylsiloxane(H-PDMS)/polyacrylate composite emulsion was synthesized by a drop-adding method for monomer emulsion. The effects of weight fraction of H-PDMS on the stability of composite emulsion, water resistance and heat-aging resistance of the latex membrane have been investigated. The TEM demonstrated that latex particles are a core-shell structure. By analyzing the spectrums of FTIR and ¹H-NMR, it can be indicated that H-PDMS had reacted with acrylate monomer resulting chemical bond formation. The core-shell structure and chemical bond play an important role to restrain phase separation of composite emulsion and enhance the stability of the emulsion. By analyzing the surface tension, apparent viscosity and morphological structure, the results showed that the stable composite emulsion system can be obtained in which the average latex particle size was smaller than 90 nm when weight fraction of H-PDMS is below 16% (based on the weight of acrylate monomer), the stable emulsion system can be obtained in which the average latex particle size becomes larger than 90 nm when the weight fraction of H-PDMS is above 20% of the acrylate monomer. The DSC demonstrated that the T_g of pure polyacrylate is 49°C, and there is only one T_g (35°C) when the weight fraction of H-PDMS is 13%, but there are two T_g (15°C and 25°C) when the weight fraction of H-PDMS is 16%. In addition, the water resistance and heat-aging resistance of composite latex membrane enhanced gradually with the increase of amount of H-PDMS.     

Studies on the Pseudo Ternary Phase Diagrams of Micro-emulsion Systems and Micro-emulsion Polymerization of H-PDMS/MMA/ n-BA

The pseudo phase diagrams of the systems of (OP-10/SDS)/butanediol-hydrogen-contained polymethylsiloxane (H-PDMS)/methyl methacrylate (MMA)/n-butyl acrylate (n-BA)–water, with different amounts of H-PDMS, were drawn. PDMS/P (MMA-BA) nano-composite latex particles were prepared by micro-emulsion polymerization, and the initiator was dripped into the micro-emulsion. The experiment results showed that when the amount of H-PDMS was in the range of 2.5～3.5%, the area of O/W of micro-emulsion in pseudo phase diagram was relatively large, while when the amount of H-PDMS was less than or greater than 2.5～3.5 %, the area of O/W of micro-emulsion was relatively small. In the micro-emulsion polymerization process, the average size of latex particles was dominated by the amount of initiator and the polymerization temperature. The experiment results also indicated that the size of the PDMS/P (MMA-BA) nano-composite latex particles is in the range of 26–65 nm, with the concentration of the initiator in the range of 0.6 × 10^–2-1.46×10^?2mol/L, at temperature 60–65°C.     

Polysiloxane-Diamine Modified Gel as Precursor to Crystalline/Amorphous Si3N4

New hybrid organic-inorganic materials are prepared by reaction of polymethylhydrosiloxane (PMHS) with aniline (An) or 4,4-diamino,diphenyl methane (APM) through a condensation between NH₂-terminated amines and Si—H groups. The obtained modified-polysiloxane is a liquid polymer (PS-An) in the first case and a cross-linked gel (PS-APM) in the second one. The chemical structures of PS-An and PS-APM were investigated by ²⁹Si nuclear magnetic resonance and were proved to be formed of created (Si—O)₂(Me)Si—N(H)— and unreacted (Si—O)₂(Me)Si—H sites. The pyrolysis of the diamine-based gel has been carried out in N₂ atmosphere up to 1450°C. FTIR, ²⁹Si MAS NMR and X-ray diffraction have shown that Si—O and Si—C bonds are totally broken during pyrolysis and that the final product is formed of crystalline and amorphous silicon nitride in the presence of a free carbon phase.     

Synthesis of alkyl polymethylsiloxane (APMS) by condensation reaction and study of properties as lubricants

The alkyl polymethylsiloxane (APMS) was prepared by condensation reaction from low hydrogen contenting polymethylsiloxane (l-HPMS) and 1-Chloroalkane, with aluminum chloride as catalysts. In the experiment, the optimum reaction conditions were determined as follows: reaction time 7 h, reaction temperature 150℃, Si-H:C-Cl 1:1.1 and amount of catalyst 4%. The effects of molecular structure on viscosity-temperature characteristics and lubrication performance of APMS were investigated. The viscosity-temperature characteristics reached the optimum with low chain unit ratios and high degree of polymerization. The lubrication performance increased with the increase of the chain unit ratios and degree of polymerization. In addition, effects of the alkyl length were also considered. The viscosity-temperature characteristics decreased, but lubrication performance of APMS increased with the increase of alkyl length.     

苯丙共聚物-聚硅氧烷复合固相微萃取涂层的制备及性能研究

合成了苯乙烯-丙烯酸乙酯共聚物,以此聚合物与甲基聚硅氧烷色谱固定液混合作为固相微萃取头涂层。通过热分析手段考察了该涂层的热稳定性,涂层使用温度可达280℃。使用微量进样器和不锈钢毛细管,自制了SPME装置。使用该涂层萃取分析了水中氯苯系化合物,各标准样品质量浓度在0—20μg／L内与色谱峰面积呈良好线性关系（r=0．9674—0．9934）,检出限为0．28—0．64ng／L,相对标准偏差为5．4％-7．7％,加标回收率为91％-99％。将自制涂层与商品涂层（PDMS、PA）进行了比较,结果表明苯丙聚合物-甲基聚硅氧烷复合涂层对氯苯系化合物具有优良的吸附特性。在固相微萃取研究和应用中,提供了新的吸附物质和色谱固定液与石英纤维结合的新途径。     

含氢聚甲基硅氧烷/丙烯酸丁酯/羟甲基丙烯酰胺复合乳液的制备方法对乳液性质的影响

采用自由基引发剂用３种不同的聚合方法制备了新型的含氢聚甲基硅氧烷（ＰＨＭＳ）／丙烯酸丁酯（ＢＡ）／羟甲基丙烯酰胺（ＮＭＡ）复合聚合物乳液。详细讨论了不同聚合方法对乳液稳定性和乳胶粒子的影响，同时对聚合反应的机理、产物的结构作了考察．结果表明：通过乳液聚合，得到了ＰＨＭＳ／ＢＡ／ＮＭＡ共聚物；单体乳液滴加法所得乳液粒径较小，乳液性能稳定，是制备ＰＨＭＳ／ＢＡ／ＮＭＡ复合聚合物乳液较适宜的方法．     

氢封端聚二甲基硅氧烷的定性分析

使用气相色谱质谱联用（GC-MS）和电喷雾四极杆飞行时间质谱（ESI-Q-TOF）对氢封端聚二甲基硅氧烷进行分析,通过谱图解析,确定了样品中有100个相对分子质量134~3 908的组分,分别属于4种同系物,包括2种链状聚二甲基硅氧烷和2种环状聚二甲基硅氧烷.     

New sparse polymethylsiloxane dendrimers

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二硅烷表面活性剂的合成与表面性能测定

合成了一种新型有机硅表面活性剂--聚醚改性二硅烷。 首先以(CH3)3SiCl和(CH3)2HSiCl为原料,金属钠作还原偶合剂,二甲苯作溶剂,用Wurtz偶合法合成了含氢二硅烷,对其结构进行了红外光谱、紫外吸收光谱和气相色谱表征,并确定了合成最佳反应条件：n((CH3)3SiCl)∶n((CH3)2HSiCl)=1.2∶1,反应物浓度为1.8 mol/L,助剂15-冠醚-5用量为总反应原料质量的2%,反应温度为80 ℃,反应时间为11 h。 再以合成的含氢二硅烷和甲基封端烯丙基聚醚（Mr=400）为原料,在Karstedt铂催化剂作用下进行硅氢加成反应,合成了聚醚改性二硅烷表面活性剂,确定的合成反应最佳温度为95 ℃,时间为4 h;该表面活性剂的表面张力为22.49 mN/m,临界胶束浓度为0.9 g/L,在pH值为6.94和4.12的水溶液中,具有良好的水解稳定性。