SYNTHESIS OF WATERBORNE ACRYLIC-CASEIN NANOPARTICLES

N. FIGUEROA; M.L. PICCHIO; R.J. MINARI; V.D. GONZALEZ; M.C.G. PASSEGGI(H); J.R. VEGA; M.J. BARANDIARAN; L.M. GUGLIOTTA

Bahia Blanca

Simposio; IX Simposio Argentino de Polímeros; 2011

Natural proteins, as casein, were widely used for long time in paper coatings, adhesives, glues, paint binders and so on, because the reduced environmental impact, high degradability, good stained acceptance, finishing glazed aspect and good paper penetrability. However, the caseinfilms present low wet rub resistance, susceptibility to microbial attack, and poor mechanical properties (brittleness). Therefore, casein has been replaced in many applications by synthetic polymers, which provide better mechanical properties, but resigning the good penetration and adhesion to substrates, and the low environmental impact that natural product offer. The synthesis of hybrid latexes containing proteins has been gaining technological interest because it attempts to modify and improve the properties of the natural substance by incorporating a second material, such as (meth)acrylates The adequate balance between the application properties of casein and those of the acrylic polymers are achieved when they form a compatible system. For that, the acrylic polymer should be chemically linked to casein.Then, the extent of grafted of casein to the acrylics (casein degree of grafting, CDG), is critical to develop a successful polymerization strategy. A one-step procedure for producing protein-poly(methyl methacrylate (PMMA) nanoparticles was proposed by Li et al. (2002). It consists on using alkyl hydroperoxide in order to initiate the polymerization on the amino protein according to a redox mechanism. Then, the emulsion polymerization was promoted by the amphiphilic radicals produced by the propagation of the amino protein radical. In this work the emulsion polymerization of acrylic monomers in presence of casein was investigated. With the objective of producing acrylic-protein compatibilized nanoparticles, different initiator types, monomer/casein formulations, and the use of functionalized casein was studied.