Mechanosynthesized copper(i) complex based initiating systems for redox polymerization: towards upgraded oxidizing and reducing agents

Significant improvements of the recently proposed Cu(i)/VitC + water/dibenzoyl peroxide (BPO) system for the redox free radical polymerization of methacrylates in air are presented here.

Study on the Supramolecular Interaction of Dibenzoyl Peroxide(BPO) and ß-Cyclodextrin(ß-CD) by Spectrophtometry and its Analytical Application

The supramolecular interaction of BPO and ß-CD has been studied by spectrophtometry. The mechanism of the inclusion was studied. The results showed that ß-CD react with BPO to form a 2:1 or 1:1 host-guest complex.The ß-CD reacts with benzoic acid to form a 1:1 host-guest complex after the BPO was reduced by hydroxyl ammonium chloride.Based on the enhancement of the absorbance of BPO produced through complex formation, a spectrophotometric method for determination BPO in bulk aqueous solution in the presence of ß-CD was developed. A linear relationship between the absorbance and BPO concentration was obtained in the range of 0.2～50 μg.ml-1. The proposed method was used to determine the BPO in the flour with satisfactory results. The principal advantage of the proposed method is its excellent selectivity based on molecule recognition of ß-CD and simple.

Hypercrosslinked polystyrene microspheres by suspension and dispersion polymerization

To determine the influence of particle size on the specific surface area of hypercrosslinked poly(styrene-co-divinylbenzene) (PS) microspheres, two methods were chosen for preparation of particles, suspension and dispersion polymerization. While the former method produced hundred micrometer-sized PS-S microspheres, the latter yielded PS-D particles of ca. 1-μm size. Dispersion copolymerization of styrene (St) and divinylbenzene (DVB) in ethanol was stabilized by (hydroxypropyl)cellulose (HPC) and initiated with dibenzoyl peroxide (BPO). Monodisperse 1.4-μm PS-D microspheres were prepared only in the presence of 3.6 wt% HPC. All microspheres were chloromethylated with chloromethyl methyl ether (CMME), chloromethyl ethyl ether (CMEE) or chloromethyl octyl ether (CMOE) to investigate the effect of the chloromethylation agent on the specific surface area of microspheres. Chloromethylated microspheres were hypercrosslinked in 1,2-dichloroethane (DCE) in the presence of a Lewis acid (SnCl4). The effects of the crosslinker (DVB) and DCE/microsphere ratio on properties of the product were studied. The specific surface area, pore volume and pore size distribution of the microspheres were analyzed by dynamic desorption of nitrogen, cyclohexane regain and mercury porosimetry.