ISSN:
0098-1273
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The Leary-Williams model for the microphase thermodynamics of triblock ABA copolymers has been modified to accommodate deviations from homogeneous random-coil configurations in the B-chain dimensions as well as in those of the A chains, and has also been extended to cover the case of diblock AB copolymers. Only planar morphology is considered, but qualitative conclusions reported herein are expected to hold for other morphologies as well. The focus is on interphase thickness ΔT, with predictions made also for separation temperature Ts and planar repeat distance D. Results are presented as systematic functions of copolymer composition (0 ≤ φA ≤ 1), total molar volume (25,000 ≤ Ṽ ≤ 4 × 106 cm3/g mol), block architecture (AB vs. ABA), temperature (298, 373 K), and for five different interphase composition profiles. In most cases, A represents a polystyrene block and B a butadiene block in these calculations. Predictions for ΔT increase with temperature and depend on architecture, profile, and Ṽ; comparisons with data are close, in the range 15-30Å. It is shown that Ts depends strongly on profile choice and φA, reaching a maximum in the φA midrange but always with φA 〉 0.5. The major parameter influencing D (at constant Ṽ) is architecture, with D(SB) ≈ 2D(SBS), and D(Ṽ) varies from D ∝ Ṽ0.75 at low Ṽ to D ∝ Ṽ0.5 at high Ṽ.
Additional Material:
15 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1985.180230512
