Polymer Diffusion and Mechanical Properties of Films Prepared from Crosslinked Latex Particles

By Patrick Pinenqt , Mitchell A Winnik, Benoit Ernst , Didier Juhue

We describe energy transfer (ET) measurements to follow polymer diffusion, as well as oscillatory dynamic mechanical measurements and tensile measurements, on films prepared from structured and unstructured latex particles consisting of a copolymer of butyl methacrylate and butyl acry­late with a Tg of 20°C Structure was introduced in the form of a low level (1 mol%) of crosslinking, using seeded semi-continuous emulsion polymer­ization to control the locus of the crosslinking agent in the particles.

Linear dynamic mechanical measurements showed the G’ and G” were sensi­tive to the particle morphology, with particular sensitivity exhibited by the elastic modulus G’. The tensile properties were less sensitive to par­ticle morphology; sufficient polymer diffusion oc­curs during film formation for the films to acquire strength and toughness. As expected, crosslinking increases strength but decreases elongation to break. Some interesting compromises could be found through control of the location of the cross linked regions of the film.