Structure-property relationships of core-shell type waterborne polyacrylate-polyurethane microemulsions

Different cross-linking types of core-shell type waterborne polyacrylate-po lyurethane (PACPU) microemulsions, in which polyurethane acts as the shell of the latex particles and a copolymer of acrylate monomers as the core, we re synthesized. In the anionic polyurethane film, there is a certain degree of soft-hard phase mixing and different extents of short-range order of th e hard segments. The introduction of a polyacrylate core increases the soft -hard phase separation in the polyurethane and breaks the short-range order of the hard segments in polyurethane to some extent. The hard segments in the shell and the core cause a widened tan delta peak. This peak shifts to higher frequencies as the core-shell ratio increases and also when a Type A or Type B cross-linking structures exist. The cross-linking structure, esp ecially Type B, improves the soft-hard separation and the phase mixing of t he core and the hard segments in the shell and at the same time breaks the short-range order in the hard segments. The cross-linking structure does no t affect the thermogravimetric properties of the PAC-PU films.