1. Polymer Aggregates with Crystalline Cores: The System Polyethylene−Poly(ethylenepropylene)
- Author
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Michael Monkenbusch, Lewis J. Fetters, Dieter Richter, Lutz Willner, J. S. Huang, Bela Farago, M. Lin, Kell Mortensen, and D. Schneiders
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Stereochemistry ,Organic Chemistry ,Polymer ,Decane ,Paracrystalline ,Polyethylene ,Small-angle neutron scattering ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Copolymer ,Lamellar structure ,Structure factor - Abstract
We have studied the aggregation behavior of polyethylene−poly(ethylenepropylene) (PE−PEP) diblock copolymers dissolved in decane. For this purpose PE−PEP diblock copolymers of various molecular weights, compositions, and degrees of deuteration were synthesized via an anionic route. The structure and morphology of the aggregates was studied by small angle neutron scattering varying both the contrast as well as the polymer labeling. We found a hierarchy of structures: The PE component crystallizes in lamellar sheets (thickness 40−80 A) surrounded on both sides by a PEP brush which exhibits a close to parabolic density profile. Different aggregates form macroaggregates of needlelike shape with the PE lamellar planes in the long direction. This macroaggregation is well described by a paracrystalline structure factor. The structural parameters depending on composition and molecular weights can be well understood in terms of a free energy of formation based on a scaling model. A quantitative evaluation of the ...
- Published
- 1997
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