期刊
RADIATION PHYSICS AND CHEMISTRY
卷 78, 期 2, 页码 112-118出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.radphyschem.2008.08.005
关键词
Miniemulsion polymerization; PU; Vinyl monomer; Grafting efficiency; Morphology; Radiation
资金
- National Natural Science Foundation of China [50573070, 50773073]
- Program for Changjiang Scholars
- Innovative Research Team in University
Graft copolymers of polyurethane (PU) with various vinyl monomers were synthesized through a one-pot but two-step miniemulsion polymerization process. Firstly, the polycondensation of isophorone diisocyanate (IPDI) with hydroxyl-terminated polybutadiene (HTPB) had been performed in aqueous miniemulsion at 40 degrees C in order to obtain PU dispersions. Consecutively, an in-situ graft copolymerization of the vinyl monomers with the synthesized PU was initiated by gamma-ray radiation at room temperature. The grafting efficiency of PU with vinyl monomer (G(PU/monomer)) was calculated from H-1 NMR spectra and the particle morphology of the final hybrid latex was observed by transmission electron microscopy (TEM). As there was no monomer transferring in miniemulsion system, homogenous hybrid particles would be synthesized provided that the monomer was miscible with PU, such as styrene. With the increase of the polarity of the monomer, the compatibility of PU with monomer decreased. G(PU/monomer) varied as G(PU/styrene)(37%)>G(PU/butyl) (acrylate (BA))(21%)>G(PU/methyl) (methacrylate) ((MMA))(12%). The proportion of homogeneous nucleation would increase as the hydrophilicity of the monomer increased. High temperature would destabilize the miniemulsion so as to result in a less grafting efficiency. Compared to the phase separation during the seeded emulsion polymerization, the miniemulsion polymerization method facilitated the preparation of homogeneous materials owing to its monomer droplet nucleation mechanism. (C) 2008 Elsevier Ltd. All rights reserved.
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