Waterborne polyurethane latexes

Sapurina et al. have reported the synthesis of PANI-coated waterborne polyurethane latexes in the presence of a polymeric stabihzer, polyvinylpyrrolidone (PVP). The composite particles showed a conductivity of 10 S cm i, with good colloidal and mechanical properties [73]. Recently, Huang et al. synthesized a series of PPy-coated styrene-butyl acrylate (SBA) core-shell latex particles [74], The Tg of the composite particles was shown to be determined mainly by the core material. It was reported that the conductivity of the hybrid particles could be tuned by varying the butyl acrylate content in the SBA copolymer. The composite particles showed a conductivity of 0.17 S cm Composite particles having a photochromic dye as the core and ICP as shell, and possessing properties of photoluminescence, have been studied by Jang etal. [75]. Thin PEDOT-coated PS particles (Fig. 6.14) were reported for self-assembled crystalline coUoidal arrays with a stop band in the visible regime by Han and coworkers [76]. 

Lu, Y., Xia, Y, Larock, R. C. (2011). Surfactant-free core-shell hybrid latexes from soybean oil-based waterborne polyurethanes and poly(styrene-butyl acrylate). Proa. Ora. Coat. 71, 336-342. 

Polyfunctional aziridines are used as cross-linkers. Polyaziridines are skin irritants, and some individuals may become sensitized. Mutagenicity of polyaziridines is controversial however, dilution by coating vehicles reduces their possible toxic effects (195). Polyaziridines, such as the addition product of 3 mol of aziridine to 1 mol of trimethylolpropane triacrylate, react with polyfunctional carboxylic acids to form 2-aminoester cross-links. The main uses are to cross-hnk carboxylic acid groups on latexes and waterborne polyurethanes. Reaction with the carboxylic acid is much faster than the reaction of the aziridine groups with water, pot lives are 48-72 h. Additional cross-linker can be added to restore reactivity. 

Yongshang L, Richard CL (2007) New hybrid latexes from a soybean oil-based waterborne polyurethane and acrylics via emulsion polymerization. Biomacro 8 3108-3144... 

The coatings industry has developed waterborne paints and coatings that greatly reduce VOC emissions. Some applications include automotive coatings, interior latex paints, and polyurethane coatings (Sherman et al., 1998). 

Polycarbodiimides react with carboxylic acid and slowly enough with water so that they can be used in waterborne systems. The product of the reaction with a carboxylic acid is an AT-acylurea. Polycarbodiimides cross-link carboxylic acid-functional resins, including aqueous polyurethane dispersions and latexes (196, 197). Cross-linking occurs within several days at ambient temperature and faster with heat. 

The efforts to synthesize waterborne hybrid polymer-polymer nanopartide dispersions are due to the expected synergetic behavior of the positive properties of each polymer phase. Hybrid latexes made of alkyd resins, " polyurethanes, polydimethylsiloxane (PDMS), polyester,"" ... 

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