Cross-Linking with Epoxides

4-butandioldiglycidyl ether (BDDE) in alkaline media [39], However, this method has several deficiencies  

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Other possible reactions, such as homopolymerization (epoxide+epoxide) and epox-ide+hydroxyl group (in the latter stages of cure), can be neglected when the ratio of epoxide to amine is stoichiometric and in the absence of catalyst or accelerator [194], For TGDDM/DDS resins, the homopolymerization reaction may be neglected at cure temperature below 180°C [84], At temperatures between 177°C and 300°C, dehydration and/or network oxidation occur, which results in formation of ether cross-linkings with loss of water. Decomposition of the epoxy-OH cure reaction can also take place, which results in propenal... 

Now a closer look at the mapping of vinyl PB can be considered. A further refinement of the total PB citations revealed 926 references for vinyl PB, which are mapped in Fig. 4. Here, the aqueous preparation of syndiotatic 1,2-PB is seen along with the use of both syndiotatic and atactic PB in tire beads, silica containing treads, and even medical applications after cross-linking with peroxide or radiation.Mixtures of catalysts have been used to allow amorphous 1,2-PB to be coproduced with syndiotatic PB in the same reactor.Epoxidized vinyl PB can be used to reduce tire rolling resistance, toughen resin, and stabilize PVC... 

Recently, a series of polymer-anchored tungsten carbonyl catalysts based on modified polystyrenes was prepared [86]. Polymer modification was carried out by reaction of chloromethylated polystyrene (2% cross-linked with DVB) with diphosphines, di- and triamines, pyrazine, 4,4 -bipyridine, and imidazole. The polymers were treated with W(CO)6(TEIF) and their catalytic performance was evaluated in the epoxidation of cyclooctene. Different solvents and oxidants were tested and epoxide yields up to 98% were obtained using the system CH3CN/ H2O2. A detailed catalyst recycling study was carried out and the catalyst containing 4,4 -bipyridine units kept constant activity over 10 reactions whereas other catalysts revealed deactivation. 

Typical of the epoxidized diene polymers are the products produced by treatment of polybutadiene with peracetic acid. Epoxidized diene polymers are not very reactive toward amines but may be cross-linked with acid hardeners. Cured resins have substantially higher heat-distortion temperatures (typically, 250°C) than do the conventional amine-cured diglycidylether resins. 

Largely unsaturated PHAs have been cross-linked by a very slow chemical procedure (it usually takes days), which implies the conversion of double bonds into epoxy groups and exposure to air (Ashby et al. 20(X)). Other epoxidized bacterial copolyesters, poly[(/ )-3-hydroxyoctanoate-co-(/ )-3-hydroxy-10,ll-epoxyunde-canoate], were cross-linked with succinic anhydride in the presence of 2-ethyM-methylimidazole or with hexamethylene diamine without a catalyst at 90°C (Lee et al. 1999a Lee and Park 1999). 

The mode of action of azinomycins is driven by the aziridino[l,2-a]pyrrolidine and the epoxide moieties which impart the capacity to form interstrand cross-links with DNA via the electrophilic C-10 and C-21 carbons of azinomycin and the N-7 positions of suitably disposed purine bases [18]. 

An oligomer containing two or more epoxide groups per molecule cross-linked with a hardener, usually diglycidyl ether of bisphenol A or pentaerythritol ... 

Epoxidized dienes are not very reactive towards amines but may be cross-linked with anhydride hardeners to give products with high heat distortion temperatures. 

The reaction is not limited to amino acids but can be extended to proteins in general [27,28]. For example, hydrolyzed wheat protein can be cross-linked with siloxane chains. These products are obtained by the reaction of epoxide or anhydride groups of organo-modified polysiloxanes with amino groups of the protein. 

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