Relation between structure and diisocyanate type in hybrids acrylic/polyurethanes studied by SAXS,WAXS and FTIR

PERUZZO, P.J.; PARDINI, O.R.; AMALVY, J.I.

Activity Report 2006 – Brazilian Synchrotron Light Laboratory

Año: 2007 p. 1 - 2

1518-0204

Polyurethane elastomers are an interesting class of materials that typically consist of semi-crystalline hard segments and amorphous soft segments. It is well known that the particular chemical structure of polyurethanes is reflected in both their morphology and fundamental properties. Due to the distinct chemical incompatibility of soft and hard segments they are thermodynamically incompatible and phase separation occurs. As a consequence a specific domain structure is formed with the result that the materials are strongly nano/microphase-separated at normal conditions. Polyurethanes are prepared using diisocyanates and polyol and the structure in the solid phase depends on the type of diisocyanate. By incorporating an acrylic component chemically bond to the polyurethane chain, hybrids materials known as nanopolymers acrylic/polyurethanes or polyurethane/acrylates are formed. In this work two types of polyurethanes dispersions prepared using isophorone diisocyanate (IPDI) and mtetramethylxylene diisocyanate (TMXDI) have been investigated. SAXS was utilized to evaluate the presence of nano/microphase separation and WAXS to explore the ordering of the hard domains. Morphology modification by including an acrylic component and by thermal curing is also investigated for both systems. FTIR experiments have also been carried out to correlate with structural changes observed in SAXS and WAXS.