Unsaturated polymers epoxidation

The systems made up of epoxidized polydienes and vinylic monomers (e.g., styrene) with mixtures of (especially unsaturated) anhydrides react in ionic catalysis or with radicalic initiators, yielding solid products with various applications. Mixed with other unsaturated polymers, epoxidized polydienes can become solid materials in the presence of radicalic initiators or can participate in sulfur vulcanization of rubber mixtures. 

Unsaturated polymers undergo reactions such as isomerisation, cyclisation, addition, epoxidation and hydrogenation. Saturated polymeric hydrocarbons undergo substitution on the main chain or the side chain. Loaded butyl vulcanisates were shown to be less... 

Warwel, S., Demes, C., and Steinke, G. (2001) Polyesters by lipase-catalyzed polycondensation of unsaturated and epoxidized long-chain a,co-dicarboxylic acid methyl esters with diols. J. Polym. Sci. Part A Polym. Chem., 39 (10), 1601-1609. 

Unsaturated polymers, prepared from butadiene or isoprene, can be epoxidized with peroxyacids. The peroxyacids used can either be preformed or prepared in situ by reacting hydrogen peroxide with lower aliphatic carboxylic acids. The epoxidized polymers can be reacted with diamines or dianhydrides to give a cross-linked resin useful for adhesive and coating applications. 

The epoxidation of NR and other unsaturated polymers has been reported in the literature. However, there are little data on the properties of these materials and, where they do exist, they tend to be conflicting. The above reactions established criteria for the chemical modification of NR, which led to the development of clean epoxidized natural rubber (ENR). These new polymers have improved oil resistance and decreased gas permeability, whilst retaining many of the properties of NR and also exhibiting some novel features. 

Epoxidation processes are based on the reaction between unsaturated polymers (solubilized in organic solvents) and peracids organically preformed or obtained in situ from the respective acids and oxygenated water. 

In the case of epoxidation with peracids formed in situ, the process occurs in a markedly heterogeneous environment, with oxygenated water and carboxylic acid to be found in an aqueous phase, and the unsaturated polymer and the solvent forming the organic phase. The peracid is formed in the aqueous phase, and it diffuses in the organic phase, where it attacks the double bond and the resulting carboxylic acid has a tendency to return the aqueous phase. This cycle continues until exhaustion of oxygenated water. 

The unsaturated polymer has via epoxidation and hydrolysis been converted into a polysaccharide type polymer. ... 

The epoxidation of diene-based polymers is advantageous because it provides active sites along the polymer chains for further modification. Furthermore, introducing an epoxide functional group to unsaturated polymers can help improve abrasion resistance, adhesive strength, and heat stability. Epox-idized polymers can be prepared by polymerizing epoxidized monomers however, this method typically results in many side reactions. Numerous reports have focused on the epoxidation of diene-based polymers with... 

Crystallinity is low the pendent allyl group contributes to the amorphous state of these polymers. Propylene oxide homopolymer itself has not been developed commercially because it cannot be cross-baked by current methods (18). The copolymerization of PO with unsaturated epoxide monomers gives vulcanizable products (19,20). In ECH—PO—AGE, poly(ptopylene oxide- o-epichlorohydrin- o-abyl glycidyl ether) [25213-15-4] (5), and PO—AGE, poly(propylene oxide-i o-abyl glycidyl ether) [25104-27-2] (6), the molar composition of PO ranges from approximately 65 to 90%. 

In polymer applications derivatives of oils and fats, such as epoxides, polyols and dimerizations products based on unsaturated fatty acids, are used as plastic additives or components for composites or polymers like polyamides and polyurethanes. In the lubricant sector oleochemically-based fatty acid esters have proved to be powerful alternatives to conventional mineral oil products. For home and personal care applications a wide range of products, such as surfactants, emulsifiers, emollients and waxes, based on vegetable oil derivatives has provided extraordinary performance benefits to the end-customer. Selected products, such as the anionic surfactant fatty alcohol sulfate have been investigated thoroughly with regard to their environmental impact compared with petrochemical based products by life-cycle analysis. Other product examples include carbohydrate-based surfactants as well as oleochemical based emulsifiers, waxes and emollients. 

Polyamino acids are easy to prepare by nucleophUe-initiated polymerisation of amino acid JV-carboxyanhydrides. Polymers such as poly-(L)-leucine act as robust catalysts for the epoxi-dation of a wide range of electron-poor alkenes, such as y-substituted a,Ji-unsaturated ketones. The optically active epoxides so formed may be transformed into heterocyclic compounds, polyhydroxylated materials and biologically active compounds such as dUtiazem and taxol side chain. 

One of the first attempts to extend polymer-assisted epoxidations to asymmetric variants were disclosed by Sherrington et al. The group employed chiral poly(tartrate ester) hgands in Sharpless epoxidations utilizing Ti(OiPr)4 and tBuOOH. However, yields and degree of stereoselection were only moderate [76]. In contrast to most concepts, Pu and coworkers applied chiral polymers, namely polymeric binaphthyl zinc to effect the asymmetric epoxidation of a,/9-unsaturated ketones in the presence of terPbutyl hydroperoxide (Scheme 4.11). 

S. Itsuno, M. Sakakura, and K. Ito, Polymer-supported poly(amino acids) as new asymmetric epoxidation catalyst of a,)3-unsaturated ketones, J. Org. Chem. 

As a second example, there is a wide variety of breakdown products and oligomeric products that may be formed from the reactive monomers that are the building blocks of plastics. For plastics, the general assumption has been that any side-reaction products and breakdown products are likely to be significantly less toxic than the monomers, and so restricting the migration of the monomer was accepted as an indirect way to limit any hazard from the oligomers also. Whilst this approach is probably acceptable for addition polymers, such as those made from the unsaturated monomers vinyl chloride, butadiene and acrylonitrile where the unsaturated monomer is far more noxious than their products, the validity of this means of indirect control is questionable for condensation polymers such as polyesters and for polyethers formed from epoxide monomers. 

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