Phase Behavior, Structure, and Properties of Model Block Polymers
Abstract
This project brought together three distinct experimental methods in an integrated investigation of the phase behavior, structure and properties of block copolymers in the vicinity of the order-disorder transition. Anionic polymerization of polydiene diblock copolymers followed by catalytic hydrogenation was used to produce three classes of model saturated hydrocarbon materials. Dynamic mechanical spectroscopy and large amplitude dynamic shearing were employed to probe and manipulate, respectively, the melt state microstructure. Small angle neutron scattering (SANS) experiments provided detailed information regarding the structure of the materials. A significant achievement during this work was the development of a dynamic shearing device that could be operated in situ with a SANS instrument. Together with the spectrum of materials produced, this combined scattering-rheology technique has led to a qualitative improvement in our understanding of block copolymer phase behavior, and uncovered a rich polymorphism that is accompanied by dramatic variations in physical properties. Two new parameters have been shown to play a crucial role in determining block copolymer phase behavior. The degree of polymerization, controls the extent of composition fluctuations which strongly affects the types of phases encountered near the order-disorder transition. Conformational asymmetry, which is controlled by the block volume and radius of gyration, leads to different phases on either side of the phase diagram. These effects have not been accounted for theoretically.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 14, 1993
- Accession Number
- ADA277530
Entities
People
- Frank S. Bates
Organizations
- University of Minnesota