Vinyl chloride monomer production catalysed by gold: A review

In this review we discuss the history of research into the use of gold for the acetylene hydrochlorin‐ation reaction, and describe the recent developments which have led to its commercialisation. We discuss the use of different precursors and the addition to gold of a secondary metal as methods which attempt to improve these catalysts, and consider the nature of the active gold species. The vast majority of poly vinyl chloride （PVC） produced globally still uses a mercuric chloride as a cata‐lyst, despite the environmental problems associated with it. Due to the agreement by the Chinese government to remove mercury usage in the PVC industry over the course of the next few years there is an obvious need to find a replacement catalyst;the potential use of gold for this process has been well known for several decades and to date gold seems to be the best candidate for this, pri‐marily due to its superior selectivity when compared to other metals.

Evaluation in vinyl chloride monomer-exposed workers and the relationship between liver lesions and gene polymorphisms of metabolic enzymes

AIM： To analyze occupational health hazards exposure to doses lower than the Chinese occupational health standard in a selected VC polymerization plant in China, and also to elucidate the relationship between genetic polymorphisms and genetic susceptibility on liver lesions of workers exposed to vinyl chloride monomer （VCM）. METHODS： In order to explore the mechanism of VCM- related health effects, we used a case-control design to investigate the association between the genetic polymorphisms of metabolic enzymes and liver lesions in workers occupationally exposed to VCM. Genotypes of CYP2E1, GSTT1, GSTM1, ALDH2 and ADH2 were identified using PCR and PCR-RFLP. RESULTS： Even when the concentration of VCM was lower than the current Chinese occupational health standard, neurasthenia, pharyngeal irritation, liver ultrasonography abnormalities and hemoglobin disorders were significantly higher in exposure subjects compared to non-exposure subjects, and the relative risks （RRand 95% C1） were 1.74 （1.06-2.85）, 1.97 （1.56-2.48）, 10.69 （4.38-26.12）, and 2.07 （1.20-3.57）. CYP2E1 c1c2/c2c2 genotype was significantly associated with liver damages （OR 3.29, 95% CI 1.51-7.20, P〈0.01）. CONCLUSION： The incidences of neurasthenia and liver ultrasonography abnormalities significantly increase when the cumulative exposure dose increases. The genotypes of metabolic enzymes （CYP2E1 c1c2/c2c2, null GSTT1 and ADH2 1-1） play important roles in VCM metabolism. Polymorphisms of CYP 2E1, GSTT1 and ADH2 may be a major reason of genetic susceptibility in VCM-induced hepatic damage.

Structure and Properties of Silk Fibers Grafted with Vinyl Siloxane Monomer

Silk fibers were grafted with a novel vinyl siloxane monomer. The properties of silk with different grafting yield were discussed. The results showed that the crease recovery of grafted silk fabric is improved significantly, handle of grafted silk is softer, and grafting has no influence on strength of silk. Graft with low grafting yield has no effect on dyeing properties of silk. The results of IR, SEM photographs and amino acid analysis indicate that the monomer combines with silk fiber by physical sediment and chemical bond, the grafting reactions mainly occurred on Ser., His. and Arg. of silk fibers, and ester crosslinking forms between silanol and Asp., Gin. of silk molecular side chains. X-ray diffraction patterns of silk fibers suggest that the grafting has no effect on the crystalline regions.

RADICAL POLYMERIZATION OF VINYL MONOMER INITIATED BY CERIC ION/TARTARIC ACID

The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid. The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been studied. The presence of the species of tartaric acid in Polyacrylonitrile produced by using ceric ion/tartaric acid as niitiator has been confirmed by FT-IR analysis.

Lewis pairs polymerization of polar vinyl monomers

The globally increasing demands for polymer materials stimulate the significantly intense attention focused on the Lewis pair polymerization(LPP) of various polar vinyl monomers catalyzed by Lewis pairs(LPs) composed of Lewis acid(LA) and Lewis base(LB). According to the degree of interaction between LA and LB, LPs could be divided into classical Lewis adduct(CLA), interacting Lewis pair(ILP) and frustrated Lewis pair(FLP). Regulation of the Lewis basicity, Lewis acidity, and steric effects of these LPs has a significant impact on the polymer chain initiation, propagation and termination as well as chain transfer reaction during polymerization. Compared with other polymerization strategies, LPP has shown several unique advantages towards the polymerization of polar vinyl monomers such as high activity, control or livingness, mild conditions, and complete chemo-or regioselectivity. We will comprehensively review the recent advances achieved in the LPP of polar vinyl monomers according to the classification of the employed LPs based on different LAs, by highlighting the key polymerization results, polymerization mechanisms as well as the currently unmet challenges and the future research directions of LPP chemistry.

Hybrid copolymerization of cyclic and vinyl monomers

In this work, we report the hybrid copolymerization of various cyclic monomers and vinyl monomers. Our studies demonstrate that 1-tert-butyl-4,4,4-tris-（dimethylamino）-2,2-bis[tris（dimethylamino） phophoranyliden-amino]-2A5,A5-catenadi（phosphazene） （t-BuP4） can catalyze the hybrid copolymerization of caprolactone （CL）, lactide （LA） or cyclic carbonate ester with acrylate or methyl acrylate. However, the polymerization of cyclosiloxane with vinyl monomers yields two corresponding homopolymers, and the polymerization of lactone with acrylonitrile （AN） produces only polyacrylonitrile. Clearly, the extent of matching of activity between a monomer and an active center determines whether or not there is hybrid copolymerization.