Microphase Separation and Crystallization in H-Bonding End-Functionalized Polyethylenes

Abstract

Well-defined, crystalline, low molar mass polyethylene PEx (where x is the molar mass 1300 and 2200 g mol–1) bearing thymine (Thy) or 2,6-diaminotriazine (DAT) end groups have been synthesized from amino-terminated PE. Either double-layer or monolayer solid-state morphologies were attained depending on the nature of the end-group(s). PE1300-NH2, PE1300-DAT, and the equimolar blend PE1300-Thy/DAT-PE1300 all organized into double-layer structures composed of extended PE chains sandwiched between H-bonding chain-ends. The double-layered morphology arose from the microphase separation of the polar end-groups and the nonpolar PE chains and was frozen by the crystallization of the PE domains. The regularity of the PE lamellar stacking was higher for the stronger and more directional associated pair Thy/DAT compared with samples of either PE-NH2 or PE-DAT. For PE1300-Thy, the mesoscopic organization was driven by the crystallization of Thy domains prior to crystallization of the PE chains, forcing the small prop...