CROSS-LINKING OF ISOCYANATE FUNCTIONAL ACRYLIC LATEX WITH TELECHELIC POLYBUTADIENE - II - FILM FORMATION CROSSLINKING/

The mechanism of film formation and crosslinking in a poly(methyl meth acrylate/n-butyl acrylate/TMI(R)) (PMBT) and amino-telechelic polybuta diene (PBD-NH2) latex blend was studied. Films cast from the latex ble nds were ultramicrotomed and examined by transmission electron microsc opy. The PBD-NH2 was found to be located primarily at the surface of t he PMBT particles due to a crosslinking reaction. Without the possibil ity of crosslinking (when TMI was absent in the acrylic copolymer), th e PBD-NH2 only formed segregated phases in the acrylic polymer matrix due to the incompatibility of the two polymers. While this PBD-NH2 cou ld be extracted with toluene, the PBD-NH2 crosslinked at the PMBT part icle surfaces was not extractable. FTIR results showed that the isocya nate groups in the PMBT were completely consumed when the PBD-NH2 conc entration was sufficiently high, indicating that the PBD-NH2 had diffu sed and reacted inside the PMBT particles. Thus, the crosslinking reac tion was considered to be the driving force for the diffusion of the P BD-NH2 into the PMBT particles. (C) 1998 John Wiley & Sons, Inc J Appl Polym Sci 69: 977-984, 1998.