Preparation of acrylic/silica nanocomposites latexes with potential application in pressure sensitive adhesive

In this study, a definite ratio of 2-ethylhexyl acrylate/acrylic acid/methyl methacrylate (2-EHA/AA/MMA) monomers was considered for the preparation of latexes through miniemulsion polymerization with applicability in pressure sensitive adhesives. Then latexes containing 0 to 4 wt% of nanosilica were prepared and their characteristics were studied. The presence of nanosilica particles in the final product was verified and its content was measured through ICP and TGA analyses. Particle size and morphological properties were studied by DLS, SEM and TEM analyses and finally rheological and adhesion properties of the samples were discussed. It was found that in the presence of nanosilica, larger particles ranging from 68 up to 152 nm with wider distribution were obtained. The results revealed that silica particles have been located in the shell of latex particles due to their hydrophilic characteristics. Also silica nanoparticles are incorporated in the polymeric particles entirely by comparing the results of ICP and TGA analyses. Rheological studies showed that by increasing the amount of nanosilica, elastic and loss modulus and also viscosity have been increased. Further investigations on the adhesion properties such as tack, peel and shear strength showed a considerable improvement in tack resistance up to 300% for the nanocomposite films containing 4 wt% of nanosilica.