UV resistance of encapsulated low molecular weight aromatic compounds in fluoroalkyl end‐capped trimethoxyvinylsilane oligomer/silica nanocomposites

Sol–gel reactions of fluoroalkyl end‐capped trimethoxyvinylsilane oligomer in the presence of low molecular weight aromatic compounds (ArH) such as 1,1′‐bi(2‐naphthol) (BINOL) and 2‐hydroxy‐4‐methoxy benzophenone (HMB) were found to proceed smoothly under alkaline conditions at room temperature to give the corresponding fluorinated oligomeric silica nanocomposites‐encapsulated aromatic compounds (BINOL and HMB) [R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites]. UV light irradiation (λ_max: 254 nm) toward R_F‐(VM‐SiO₂)_n‐R_F/ArH nanocomposites showed that photodegradation of encapsulated ArH was not observed at all in the fluorinated nanocomposites cores, although the parent ArH can exhibit an effective photodegradation behavior under similar conditions. Especially, encapsulated ArH can exhibit no weight loss corresponding to the contents of the aromatic compounds in the fluorinated nanocomposites even after calcination at 800°C. Therefore, fluoroalkyl end‐capped trimethoxyvinylsilane oligomer has high potential for not only the thermal resistance but also the UV resistance fluorinated polymeric materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of (diorgano)chloro(4-chlorobutoxy)silanes

Some novel (diorgano)chloro(4-chlorobutoxy)silanes were obtained by the reaction of dichlorodiorganosilanes with tetra hydrofuran in the presence of chloroplatinic acid.Translated fromIzvestiva Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 943–945, April, 1996.     

Kinetics of free‐radical graft polymerization of 1‐vinyl‐2‐pyrrolidone onto silica

The kinetics of aqueous free‐radical graft polymerization of 1‐vinyl‐2‐pyrrolidone onto silica activated with vinyltrimethoxysilane was studied with a mechanistic polymerization model and experimental data for a temperature range of 70–90 °C. The polymerization was initiated with hydrogen peroxide with initial monomer concentrations ranging from 10 to 40 vol %. The kinetic model, which incorporates the hybrid cage–complex initiation mechanism, describes the experimental polymerization data for which the kinetic order, with respect to the monomer concentration, varies from 1 to . Surface chain growth occurs by both monomer addition and homopolymer grafting, although the latter contribution to the total polymer graft yield is less significant. Increasing the initial monomer concentration enhances both surface polymer density and average grafted chain length. Increasing reaction temperature, however, produces a denser surface layer of shorter polymer chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 26–42, 2002