Preparation of the stable core–shell latex particles containing organic-siloxane in the shell

In this study, the latex particles with a polyacrylate core and a polydimethylsiloxane shell via 3-(methacryloxypropyl)-trimethoxysilane as the space arm to link the core and shell have been prepared by semi continuous seeded emulsion polymerization. And several key polymerization reaction conditions such as the emulsifier concentration, 3-(methacryloxypropyl)-trimethoxysilane dosages, feeding sequence and the acrylates/siloxanes ratio were detailedly discussed. Then, the optimal condition to prepare stable core/shell particles was selected and a proper preparation process has been established. The as-synthesized particles were characterized by TEM and XPS. The clear core/shell structure of the particles could be observed through analysis TEM. In addition, the results of XPS analyses manifested that siloxanes had been grafted on the surface of the polyacrylate particles and they distributed on the outmost layer of the particles. Finally, the surface hydrophobicity of the film formed by latex particles was investigated by the water absorption ratio measurement. The results indicated the developed latex particle provided with a fair water-repellency property.     

全氟磺酸盐与硅氧烷协同阻燃聚碳酸酯的研究

采用全氟磺酸盐/聚硅氧烷复合阻燃剂,制备了聚碳酸酯(PC)工程阻燃材料。通过热重分析(TGA)、微型燃烧量热测试(MCC),以及垂直燃烧性能测试等手段,研究了该阻燃材料的热降解和燃烧过程,并对复合阻燃剂的阻燃机理进行了分析。结果表明:全氟磺酸盐和聚硅氧烷具有良好的协同阻燃作用,可大幅提高阻燃效率,实现阻燃剂的小剂量化。     

Synthesis and properties of cyclopentadithiophene-based poly(silarylenesiloxane) derivatives

Poly(silarylenesiloxane) derivatives with 4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene moiety, bearing dimethyl- (P1), methylphenyl- (P2) and diphenyl- (P3) substituents on silyl moieties, were prepared via polycondensation of the corresponding disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M1), 2,6-bis(methylphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M2), and 2,6-bis(diphenylhydroxysilyl)-4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene (M3), respectively. P1-P3 exhibited the good solubility in common organic solvents, such as benzene, toluene, chloroform, dichloromethane, THF, and so on. The glass transition temperatures (T_gs) of P1, P2 and P3 were determined by differential scanning calorimetry to be 56, 97 and 137 °C, respectively, depending on the substituent on the silyl moieties. No melting temperatures (T_ms) of P1, P2 and P3 were observed, suggesting the obtained P1-P3 are amorphous polymers. The temperatures at 5% weight loss (T_d5s) of P1, P2 and P3 were 460, 459 and 479 °C, respectively, indicating that the larger number of phenyl group on the silyl moieties resulted in the better thermostability. Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra by introducing silyl substituents onto 4,4-dimethylcyclopenta[2,1-b:3,4-b′]dithiophene moiety. In addition, the bathochromic shift of the maximum absorption (λ_abs) and the increase in the fluorescence quantum yield (Φ_F) were observed by the introduction of phenyl group onto the silyl moieties.     

有机硅改性聚醋酸乙烯酯的合成与性能

采用乳液聚合制备了新的有机硅改性的聚醋酸乙烯酯 (PVAc)聚合乳液。考察了有机硅改性的PVAc乳液及胶膜的性能。结果表明该乳液具有优良的成膜性 ,粘接强度高 ,优良的耐水性和耐寒性。     

Synthesis and characterization of side-chain liquid crystalline polysiloxanes containing (S)-2-methyl-l-butyl [6-(4-alkenyloxyphenyl)-carbonyloxy]naphthylene-2-carboxylate and (S)-2-methyl-l-butyl 6-[(4-alkenyloxy-biphenyl)-4′-carbonyloxy]naphthalene-2-carboxylate side groups

The synthesis of side-chain liquid crystalline polysiloxanes containing either (S)-2-methyl-l-butyl [6-(4-hydroxyphenyl)carbonyloxy]naphthalene-2-carboxylate or (S)-2-methyl- I -butyl 6-[(4-hydroxybiphenyl)-4-carbonyloxy]naphthalene-2-carboxylate moiety as mesogenic units and aliphatic spacers containing respectively three to eleven methylene units is presented. Differentical scanning calorimetry, optical polarizing microscopy, and X-ray diffraction measurements reveal smectic mesomorphism for all polymers. Most of the obtained polymers display only an enantiotropic smectic A phase. The temperature range of the mesophase formed increases with an increase in the spacer length. All of the synthesized polymers reveal no chiral smectic C phase. The experimental results demonstrate that incorporation of a naphthalene ring in the mesogenic core decreases dramatically the tendency to form a chiral smectic C phase.     

Synthesis of novel poly{methyl-[3-(9-indolyl)propyl]siloxane}-based nonlinear optical polymers via postfunctionalization

A novel series of nonlinear optical (NLO) polysiloxanes with a high density of chromophore moieties based on poly{methyl-[3-(9-indolyl)propyl]siloxane} (PMIPS) were synthesized by a post functional strategy. First, PMIPS (P1) was prepared through hydrosilylation reaction, then P1 is partially formylated by the reaction between P1 and the reagents of dimethylformamide (DMF) and phosphorus oxychloride under the standard Vilsmeier reaction conditions, and these formyl groups with high reactivity are condensed with four predesigned cyanoacetylated chromophores to afford the series of chromophore functionalized polysiloxanes (P3-6). The most special point is the molar concentrations of chromophore moieties are the same in polymers P3-6, which makes it convenient to study the behavior of different chromophores in the polymeric system. The poled films of P3-6 reveal the resonant d₃₃ values in the range of 7.9-55.2 pm/V by second harmonic generation (SHG) measurements.     

具有活性端胺基聚硅氧烷低聚体及其改性环氧树脂的合成和结构表征

本文合成了具有活性端胺基聚二甲基二苯硅氧烷共聚物的低聚体（分子量２９４６—３１８２），用以改性双酚Ａ型环氧树脂（分子量４８０—１８００）进行交联固化，研究了不同结构组成和配比对环氧树脂改性的影响及最佳条件，随着共聚物中苯基含量的增加．提高了软段的溶度参数，使两相的相容性增加，微区尺寸减小，材料的力学性能改进，具有较好的增韧效果。对聚合物进行结构和形态的研究表明，材料表面硅氧烷富集程度不随改性剂的结构组成和含量而变化。     

含硅阻燃剂的新进展

硅化合物被期待作为新型阻燃剂。它可完全不依赖卤素和磷化合物而发挥阻燃作用。最近有关硅阻燃剂的文章和专利成为新热点，几乎所有组成的硅化合物都被用作阻燃剂研究过。含硅化合物不管是作为聚合物的添加剂，还是与聚合物组成共混物，都具有明显的阻燃作用。     

Digital light processing fabrication of porous cordierite ceramics from polysilxoane-based slurries

Herein, a pohotosentive polysiloxane (PSO)/talc/Al₂O₃ slurry was prepared for the digital light processing printing. Liquid photosensitive PSO was exploited as a triple-functioned material, acting both as the resin matrix, a high reactive Si source and a pore generator. Through adjusting the raw material components, polysiloxane can be sintered with talc and Al₂O₃ fillers after being pyrolyzed to 1200 ^oC while pores with variable diameters can be generated. Ternary component slurry prepared based on the above strategy possesses the characteristics of low viscosity, high reaction activity and good homogeneity. Sintering schedule of the printed thin-walled precursor was investigated to guarantee the morphology of cordierite product was consistent with the printed model. This work aims to provide a new strategy for DLP printing of MgO-Al₂O₃-SiO₂ ternary and other polymer derived ceramics.