Trifluoropropylmethylsiloxane–phenylmethylsiloxane gradient copolysiloxanes were synthesized by anionic and cationic ring-opening polymerization (ROP) of 1,3,5-tris(trifluoropropylmethyl)cyclotrisiloxane ( ) and phenylmethylcyclotrisiloxane ( ). The analysis of reactivity ratios revealed that the reactivity of toward anionic ROP was higher than that of ; however, exhibited lower reactivity compared with during the cationic ROP. AB and BAB type gradient copolymers were obtained because of a difference in the reactivity of the monomers. The microstructure of copolymers was characterized by ²⁹Si NMR spectroscopy, gel permeation chromatography, and differential scanning calorimetry. Furthermore, the mechanism for kinetics inverse of copolymerization was proposed based on the results of the optimized molecular configuration. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 835–843

Raspberry-like SiO₂@Polymer composite particles, prepared by one-pot Pickering emulsion polymerization in aqueous medium, were used to reinforce silicone rubber. Bearing both polymer moieties and Si−OH groups on the surface, these raspberry-like particles were better dispersed in the silicone rubber matrix; therefore the mechanical performance of the resultant particle − silicone rubber composites was significantly enhanced. With 25 phr SiO₂@Polymer composite particles, the tensile strength, elongation at break and hardness were 2.02 MPa, 129% and 38, respectively. Further increasing the filler amount resulted in decrease of the tensile strength and modulus. In the meantime, although there was a large fraction of polymeric phase in the composite particles, the thermal stability of the resultant particle − silicone rubber composites was not significantly reduced, especially for particle loading exceeding 10 phr. These raspberry-like SiO₂@Polymer composite particles are easily produced on a large scale in an environmentally friendly and cost-effective way; thus these are promising novel fillers to reinforce silicone rubber. © 2015 Society of Chemical Industry

Novel fluorine containing siloxane monomer, namely, 4-trifluoromethylphenylmethyl cyclosiloxane (PF3) and mixed cyclosiloxane including both 4-trifluoromethylphenylmethyl siloxane (P) unit and trifluoropropyl siloxane (F) unit were successfully synthesized in this study. Furthermore, their series including vinyl-terminated copolymers with different compositions were synthesized. The microstructures of copolymers were investigated by ¹H NMR, ²⁹Si NMR, ¹⁹F NMR, Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC). The results of characterizations confirmed that the copolymers exhibited random microstructure. Moreover, the analysis of the result of DSC also revealed that the copolymers had a low glass transition temperature. The thermogravimetric analysis indicated that poly(4-trifluoromethylphenylmethyl)siloxane (PPF3) exhibited higher thermal stability than conventional fluorosilicones rubber (FSR). The dynamic mechanical analysis showed that the damping factors of these copolymers were greater than 0.3 in a wide range of temperature. The mass swelling ratios were less than 5.5% when the samples were immersed in No. 3 jet fuel for a month. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1023–1031

A series of random copolysiloxanes (PCDMS) containing various amount of γ-cyanopropyl groups are prepared by a new method under mild conditions. Structures of the synthesized polymers are fully characterized by FTIR, ¹H NMR, ²⁹Si NMR, and GPC. Rheological properties of PCDMS are tested by cone and plate rheometer, and thermal properties by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). Damping properties as well as fuel resistance of the cured PCDMS elastomers are also tested. The correlation between chemical structure, content of cyanopropyl group and properties are discussed. With the increasing amount of polar cyanopropyl group introduced, glass transition temperatures (T_g) of the synthesized PCDMS gradually increases from −121 to −65 °C, residual weight increases from 0 to 36% at 800°C, loss factor reaches as high as 1.74, mass increase under fuel immersion for 14 days can be as low as 3.6%. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1408–1421

New and effective approaches to the synthesis of 1,3-bis(diphenylsilyl)-2,2,4,4-tetraphenylcyclodisilazane-containing polydimethylsiloxanes (P1 and P2) were developed. P1 was obtained by polycondensation of cyclodisilazane lithium salt and chloroterminated polydimethylsiloxane. P2 was produced by hydrosilylation of vinyl-terminated cyclodisilazane and hydrogen-terminated polydimethylsiloxane. The polycondensation completed quickly at room temperature, while the hydrosilylation was facile and did not require cumbersome air-sensitive operations. P1 and P2 were characterized by Fourier transform infrared, nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis (TGA), and isothermal gravimetric analysis (IGA). TGA revealed the outstanding thermal properties of P1 and P2 with 5% weight loss temperatures (T_d5) higher than 450°C. IGA proved their better thermal stability at 450°C for 800 min, compared to polydimethyldiphenylsiloxane. Dynamic mechanical analysis showed that silicone rubbers made from cyclodisilazane-containing polydimethylsiloxanes could have a maximum tan δ value as high as 1.13 and had good prospects for damping material applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Poly(dimethylsiloxane) (PDMS) composites were prepared by simple blending process using palygorskite (PG) or modified palygorskite (MP). This study has been designed to determine the influences of PG or MP on the thermal stability and the mechanical properties of PDMS composites. The thermal stability of PG and MP were also studied by thermogravimetric analysis (TGA). The results showed that MP had the similar thermal stability to PG, and PG or MP not only increased the thermal stability but also improved the mechanical properties of PDMS composites. Meanwhile, compared with PG/PDMS composites, MP/PDMS composites had better thermal stability and mechanical properties owing to the better dispersion of MP into the matrix, the stronger chemical interfacial interaction between MP and the matrix. Copyright © 2010 John Wiley & Sons, Ltd.

Polymeric curing agent modified with hexamethyldisilazane (PCA-D), or with hexamethylcyclotrisilazane (PCA-T), was used to improve the mechanical properties of hydroxyl-teminated polydimethylsiloxane (PDMS) rubber. The structure and the gel time of PCA were characterized by ²⁹Si NMR and shear viscosity measurement, respectively. The PCA modified with silazanes was more stable in storage than that without treatment (PCA-0). Chemical bonds were formed during the reaction of silazanes and PCA according to ²⁹Si NMR results. The crosslink density (γ_e) and the mechanical properties of PCA/PDMS rubber were determined by swelling equilibrium and stress–strain tests. It was found that PCA treated with both silazanes could better enhance the mechanical properties of PCA/PDMS rubber compared with PCA-0. PCA-T/PDMS rubber, with additional crosslinks, was the best among the three types of PCA/PDMS rubber on the mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Polysiloxane–polyester copolymers have been synthesized for the first time by direct polycondensation of a series of diacids (butanedioic, hexanedioic, and octanedioic acid) and α,ω-bis(3-hydroxypropyl) polydimethylsiloxanes catalyzed with Novozyme-435 in high yields (>90%) without the cleavage of SiO bonds. The effects of monomer chain length, reaction temperature, and water removal method on the number–average molecular weight (M_n) of the resulted copolymers were investigated. Thermogravimetric and differential scanning calorimetry analyses indicated that the produced copolymer was more thermally stable than poly(1,8-octyladipate) and the T_g was lowered to −111°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A new type of polymeric curing agent (PCA) was synthesized to improve processing property, increase mechanical properties, and decrease volume shrinkage of silicone rubber. The PCA was prepared by co-hydrolysis condensation of dimethyldiethoxysilane (DDS) and polyethoxysiloxane, then modified by hexamethylcyclotrisilazane (D₃^N). Commercial silica and tetraethoxysilane (TEOS) were used as controls simultaneously. The properties of polydimethylsiloxane (PDMS) composites were characterized by shear viscosity measurements, room temperature mass loss, linear volume shrinkage, stress-strain tests, swelling behaviors and thermogravimetric analysis (TGA). PDMS composites using PCA show lower shear viscosity than those using commercial silica. Compared with the traditional PDMS/TEOS curing systems, PDMS/PCA curing systems behave relatively lower volume shrinkage, better reinforcement and thermal properties. In short, PCA acts as a good compromise in providing the best balance of processing property, volume shrinkage, mechanical properties and thermal stability in silicone rubber composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008