Crosslinking of isocyanate functional acrylic latex with telechelic polybutadiene. III. Application of a diffusion model

Abstract

ABSTRACT:The diffusion and reaction of amino-telechelic polybutadiene (PBD-NH 2 ) in poly(styrene/ n-butyl acrylate/TMI) (PSBT) was studied. A monodisperse poly(St/ BA/TMI) seed latex was prepared by semicontinuous emulsion polymerization. Two core/shell latices were also prepared semicontinuously, using the seed latex as the core and poly(St/BA) as the shell. These monodisperse latices were mixed with equivalent amounts of the telechelic PBD-NH 2 artificial latex before casting into films. The consumption of the TMI in these films was monitored by FTIR as a function of time and the NH 2 /TMI ratio. The results showed that without the PSB shell, the PSBT particles (80 nm radius) could be penetrated by the PBD-NH 2 completely. A 24 nm PSB shell was found to act effectively as a barrier to preventing the penetration of the PBD-NH 2 inside the particles. This was consistent with previous TEM results, indicating that the crosslinking between the isocyanate in the PSBT particles and the amine in the PBD-NH 2 particles provided the driving force for the chain diffusion. A diffusion model was established for the PSBT/PBD-NH 2 system. Assuming steady-state diffusion, the effective diffusion coefficients were calculated based on the experimental data. This lead to the estimation of the surface coverage of the PBD-NH 2 on the PSBT particles in the latex films. A film formation and crosslinking mechanism was proposed for the PSBT/PBD-NH 2 latex blend system. In the absence of crosslinking reactions, the two incompatible polymers tended to completely phase separate during the film formation. However, with the crosslinking reactions, the PBD-NH 2 will be bound to the PSBT particle surfaces, forming a PSBT-PBD copolymer interphase. This interphase facilitates the diffusion of the PBD-NH 2 into the PSBT particles.

Living Polymerization of Sulfur Ylides. Synthesis of Terminally Functionalized and Telechelic Polymethylene

“…The pyrene and dansyl groups have been used as fluorescent probes to analyze surface properties, solvent accessibility, and mobility of polymers. − Carbohydrate and biotin-functionalized polymethylene polymers have potential for use in diagnostic arrays of proteins, cells, or DNA. − The accessibility and activity of molecules bound to solid-phase media have been shown to increase with the use of various spacers. , In particular, PEG spacers have been used to ensure aggregation and display of functional groups at the surface of polyethylene . Amino-terminated polymethylene has potential applications for its use in block copolymer synthesis, surfactants, metal complexation agents, and stabilizers for polyethylene. − …”

“…39 Aminoterminated polymethylene has potential applications for its use in block copolymer synthesis, surfactants, metal complexation agents, and stabilizers for polyethylene. [49][50][51][52][53]…”