Polyolefins having low polydispersity and containing terminal functional groups are difficult to synthesize, due to limitations in catalysis technology. We have developed methods for preparing model polyolefins with terminal amine or anhydride functionality and of controlled molecular weight and narrow polydispersity. Both 1,4- or 1,2-polybutadienes are prepared by living anionic polymerization, with introduction of a functional group precursor during chain termination. The functional groups are protected as tert-butyl carbamate and tert-butyl ester for the amine and anhydride, respectively. The polymers are hydrogenated heterogeneously, with subsequent deprotection yielding saturated polymers with functionalities of up to 90%. These materials, due to their low polydispersity, comprise a useful model system for measuring melt reaction kinetics by gel permeation chromatography. Melt blending of amine- and anhydride-functional PEE90 (polyethylethylene) with complementary functional polystyrenes quickly yields extensive amounts of block copolymer with complex, sub-micron scale morphologies. Similar fine morphologies are observed for blends of amine- and anhydride-functional PE (polyethylene) with functional polystyrene. These functional PE and PEE90 polymers can also be used as reactive compatibilizers for polyethylene and polypropylene blends, respectively. The concentration of compatibilizer required to obtain sub-micron particles, however, is as high as 20% by weight.
Bibliographical noteFunding Information:
The authors wish to thank NSERC Canada, the NSF, and the Center for Interfacial Engineering at the University of Minnesota for financial support. The authors also wish to thank Drs Jeffrey Cernohous and Milan Maric and Professor Frank Bates for useful discussions.
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- Drop morphology
- Polymer blends