Accession Number:

ADA315860

Title:

Thermodynamics and Processing of Block Copolymers with NLO Application.

Descriptive Note:

Final rept. 1 Mar-31 Aug 96,

Corporate Author:

MINNESOTA UNIV ST PAUL

Personal Author(s):

Report Date:

1996-08-01

Pagination or Media Count:

19.0

Abstract:

During this project more than one-hundred block copolymers, spanning seven different chemical combinations and numerous molecular weights and compositions, were synthesized using anionic polymerization and chemical modification techniques. Phase behavior was characterized with small-angle neutron scattering SANS and transmission electron microscopy, guided by dynamic mechanical spectroscopy measurements. A comprehensive picture of the phase behavior of diblock copolymers near the order-disorder transition has been established. Three new morphologies, bicontinuous with Ia3bard space group symmetry, hexagonally perforated layers HPL and hexagonally modulated layers HML have been identified along with the classical lamellar, cylindrical and spherical structures. Application of a new in-situ shear-SANS experiment has aided in elucidating the susceptibility of these phases to deformation and flow. Reciprocating shear has been shown to produce macroscopic orientation, and to shift the phase boundaries. Similar static and dynamic phenomena were found for binary mixtures of diblock copolymers, thereby demonstrating a versatile method for controlling structure and properties without the need to produce new materials at each desired composition. p1

Subject Categories:

  • Polymer Chemistry
  • Physical Chemistry
  • Thermodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE