Hyperbranched polymer with alternating ureido and urethano units was prepared by direct polymerizarion of isophorone diisocyanate(IPDI, A 2) with diethanolamine(DEOA, CB 2) in the absence of catalyst. In the reaction,...Hyperbranched polymer with alternating ureido and urethano units was prepared by direct polymerizarion of isophorone diisocyanate(IPDI, A 2) with diethanolamine(DEOA, CB 2) in the absence of catalyst. In the reaction, one isocyanato group of IPDI reacts fast with amino group of DEOA, generating an intermediate with one isocyanato group and two hydroxyl groups. Now the intermediate formed is a new kind of AB 2 type monomer. Further self-condensation of this AB 2 species leads to hyperbranched poly(urea-urethane). The reaction mechanism was characterized with in situ FTIR. Temperature and concentration have great influence on the polymerization process. When the feed ratio of IPDI to DEOA is equal to \{1∶\}1, no gelation is observed if the reaction temperature within initial several hours is lower than 20 ℃. Cross-linking would occur if the reaction temperature during initial period is high. The degree of branching(DB) of the resulting hyperbranched poly(urea-urethane) is 46.5%-48.5%.展开更多
UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly（urea-formaldehyde） shell, which was in situ formed by the polymerization of formalde-hyde and urea in an oil-in-water e...UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly（urea-formaldehyde） shell, which was in situ formed by the polymerization of formalde-hyde and urea in an oil-in-water emulsion. The diameters of the microcapsules ranged from 118 μm to 663 μm depending on agitation speed, and were obtained via optical mi-croscopy and scanning electron microscopy analyses. The encapsulation percent and the yield of microcapsules prepared at the agitation speed of 600 r/min can reach 97.52wt% and 65.23wt%, respectively. When the water-borne polyurethane （WPU） coating embedded with the prepared microcapsules were scratched, the healing agent could be released from rup-tured microcapsules and lled the scribed region. The excellent anticorrosion properties of the WPU coating embedded with the prepared microcapsules were con rmed by the results obtained from both electrochemical impedance spectroscopy and Tafel curves.展开更多
文摘Hyperbranched polymer with alternating ureido and urethano units was prepared by direct polymerizarion of isophorone diisocyanate(IPDI, A 2) with diethanolamine(DEOA, CB 2) in the absence of catalyst. In the reaction, one isocyanato group of IPDI reacts fast with amino group of DEOA, generating an intermediate with one isocyanato group and two hydroxyl groups. Now the intermediate formed is a new kind of AB 2 type monomer. Further self-condensation of this AB 2 species leads to hyperbranched poly(urea-urethane). The reaction mechanism was characterized with in situ FTIR. Temperature and concentration have great influence on the polymerization process. When the feed ratio of IPDI to DEOA is equal to \{1∶\}1, no gelation is observed if the reaction temperature within initial several hours is lower than 20 ℃. Cross-linking would occur if the reaction temperature during initial period is high. The degree of branching(DB) of the resulting hyperbranched poly(urea-urethane) is 46.5%-48.5%.
文摘UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly（urea-formaldehyde） shell, which was in situ formed by the polymerization of formalde-hyde and urea in an oil-in-water emulsion. The diameters of the microcapsules ranged from 118 μm to 663 μm depending on agitation speed, and were obtained via optical mi-croscopy and scanning electron microscopy analyses. The encapsulation percent and the yield of microcapsules prepared at the agitation speed of 600 r/min can reach 97.52wt% and 65.23wt%, respectively. When the water-borne polyurethane （WPU） coating embedded with the prepared microcapsules were scratched, the healing agent could be released from rup-tured microcapsules and lled the scribed region. The excellent anticorrosion properties of the WPU coating embedded with the prepared microcapsules were con rmed by the results obtained from both electrochemical impedance spectroscopy and Tafel curves.
