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Herein, a compound has been developed via melt blending and curing of poly(styrene–ethylene butylene–styrene) triblock copolymer (SEBS) with silicone rubber (SR). The cure characteristics, mechanical, thermal, and dynamic mechanical properties of the SR/SEBS blends of different mass ratios (100/0, 90/10, 75/25, 50/50, 25/75, and 0/100) are investigated. The cure characteristics reveal that the crosslinking and cure rate of SEBS are lower than SR. The cure rate of SEBS is 0.35 dN.m/min, while it is 15.35 dN.m/min for SR. Also, in the blends, as the content of SR increased, the crosslinking and cure rate of the blends show an upward trend. The results of mechanical properties indicate that the presence of SEBS with a formed (simultaneously physical and chemical) double network can strengthen the mechanical properties of SR, as the tensile strength and elongation at break of the blends improve by increasing the content of SEBS. It is found that adding 25% of SEBS to SR enhances the tensile strength and elongation at break of the SR blend from 5.66 to 7.56 MPa and from 116 to 185%, respectively. Thermogravimetry demonstrates the better thermal stability of SR than SEBS and the blends. The obtained primary thermal parameters reveal that the thermal stability of the SEBS phase in the blends improves with growing the SR content. Dynamic mechanical thermal analysis exhibits two loss tangent peaks for SEBS at 119.61 and − 45.36 °C, which are related to the glass transition temperatures of polystyrene (as a physical crosslinker phase) and ethylene–butylene blocks, respectively. Also, two peaks are observed for SR at − 37.16 and − 134.16 °C. Differential scanning calorimetry confirms that the two temperatures are related to the melting and glass transition temperatures of SR, respectively. [ABSTRACT FROM AUTHOR]

In this study, a macroinitiator of β-CD-ONa was prepared by a substitution reaction of β-cyclodextrin (β-CD) with sodium (Na). The macroinitiator was then used in the ring-opening polymerization of octamethylcyclotetrasiloxane (D4) to obtain a star polymer, in which β-CD is the core and polysiloxane is the arm. FTIR, NMR, TGA, CA, etc., were used to characterize the structure and properties of star polymers. The results indicated that there were four polysiloxane arms attached to each β-CD core, and the star polymer had good thermal stability. With the increase in D4 monomer dosage, the hydrophobicity of the star polymer slightly improved, but the reaction time had no significant effect on hydrophobicity. When the star polymer was coated onto polyethylene terephthalate membrane, the transmittance increased from 87.6% to 92.8%, and the haze did not change significantly. Furthermore, the surface of star polymer porous membranes was prepared by the static breath-figure method using n-hexane as solvent at 30 °C. The results showed uniform pore distribution and increased hydrophobicity. [ABSTRACT FROM AUTHOR]

Double methyl oleate (MO) capping agent (MO-MM-MO) was prepared by hydrosilylation, from MO and tetramethyldisiloxane (HMMH). The structure was characterized by IR spectrum. By investigating the effects of different catalysts and reaction conditions on the hydrosilylation conversion, the H2PtCl6·6H2O/isopropanol solutions was selected as catalyst, and the optimal reaction conditions were determined. The double MO-terminated polysiloxane (MOM-Dn-MMO) with different degree of polymerization (DP) was prepared via octamethylcyclotetrasiloxane (D4) ring opening polymerization, with MO-MM-MO terminated. The effects of DP on the performance of MOM-Dn-MMO were studied. With the increase in DP, the viscosity-temperature performance of product gradually increases, and it remained basically unchanged, when the DP was 60 or more. For the lubrication performance, as the DP increased, the product lubrication performance improved gradually, and compared with polydimethylsiloxane (M-Dn-M), the lubrication performance of MOM-Dn-MMO was also more excellent. The products with large DP had good thermal stability, also. In addition, the effects of product on the mineral oil performance were also investigated. The MOM-D40-MMO was good compatible with mineral oil, and the lubrication performance of mineral oil with MOM-D40-MMO was also improved, due to the presence of MO. [ABSTRACT FROM AUTHOR]

Polysiloxane derivatives having quaternized imidazolium moieties with different length of alkyl chains ( [HPIm n ]Cl) ( n is the number of methylene group) were prepared via quaternization reaction of poly(3-chloropropylmethylsiloxane) ( P1) with 1-alkylimidazole derivatives ( Im ns). [HPIm n ]Cls were obtained with high quaternization ratio from 95 to 100 mol%. The glass transition temperatures ( T s) of a series of [HPIm n ]Cls were lowered with increase in the length of alkyl chain in the case of the number of methylene group from 1 to 6; however, those were a little raised when the number of methylene group was 7 and 8 plausibly owing to the effects of the van der Waals interactions among long alkyl chains. [HPIm n ]Cls were dissolved in high polar solvents such as methanol, dimethyl sulfoxide, N, N-dimethylformamide and water. Also, the increase in the length of alkyl chains in [HPIm n ]Cls improved the solubility in low polar organic solvents such as chloroform and dichloromethane. [ABSTRACT FROM AUTHOR]

Research deals with the assessment of grafting of cyclosiloxanes onto organically modified montmorillonite (MMT) layers through anionic ring-opening polymerization (AROP) without additional catalyst or initiator. Pristine Na-MMT was organically modified by systematically varying the hexadecyltrimethylammonium bromide (HDTMABr) loading level. X-ray diffraction and thermogravimetric analysis of differently modified MMTs (OMMTs) showed that HDTMABr cations that exchanged sodium cations were strongly attracted to the silicate platelet surfaces. Part of HDTMABr formed a sandwiched HDTMABr layer between organically modified silicate platelets. The obtained OMMTs were tested as initiator material for AROP of octamethylcyclotetrasiloxane (D4) in the bulk, since the D4 polymerization may be initiated by oxygen anions located on the silicate surfaces. The highest monomer conversion (91 % after 24 h at 80 °C) was observed when OMMT with HDTMABr amount equal to cation exchange capacity was used. At lower amounts of HDTMABr, the MMT was less organically modified and thus less compatible with D4. On the other hand, when the HDTMABr sandwiched layer was thicker, lower rates of polymerization were observed due to the hindered transport of monomer to silicate platelet surfaces. The active function of surface anions in MMT platelets in the initiation process was confirmed experimentally by varying the OMMT/D4 ratio. It was observed that monomer conversion increased with increasing OMMT/D4 ratio. The obtained composites were exfoliated. In the last part of the research, OMMT was added to the formulation for D4 emulsion polymerization, where HDTMABr was also used as an emulsifier. The obtained composite material had a significantly improved thermal stability. [ABSTRACT FROM AUTHOR]