Block copolymers morphological effects

Figure 7.12 Effect of composition on block copolymer morphology (a) spheres of A in matrix of B (b) cylinders of A in matrix of B (c) alternating A and B lamellae (d) cylinders of B in matrix of A and (e) spheres of B in matrix of A.

Woodward, A. E., Atlas of Polymer Morphology , Hanser, New York, 1989. Useful book for the practising morphologist. It discusses crystallization from the melt, block copolymers, processing effects, blends, fracture and effects of chemicals and other agents. 

Mostly, the effect of film thickness on the block copolymer morphology has been studied for systems that form lamel-lae. For example, the effect of the continuous decrease of the thickness on the block copolymer morphology is illustrated by results obtained by Fasolka for PS-b-PnBMA films, as shown in Figure 43. The film thickness decreases from A to D, being equal to Lo on the extreme right (A). Under this condition, the block copolymer morphology is formed by lamellae parallel to the substrate and there is no contrast to be observed on that area of the TEM image. 

As more complex multicomponent blends are being developed for commercial appHcations, new approaches are needed for morphology characterization. Often, the use of RuO staining is effective, as it is sensitive to small variations in the chemical composition of the component polymers. For instance PS, PC, and styrene—ethylene/butylene—styrene block copolymers (SEES) are readily stained, SAN is stained to a lesser degree, and PET and nylons are not stained (158,225—228). 

Puskas J.E., Antony P., ElFray M., and Altstadt V. The effect of hard and soft segment composition and molecular architecture on the morphology and mechanical properties of polystyrene-polyisobutylene thermoplastic elastomeric block copolymers, Eur. Polym. J., 39, 2041, 2003. 

Pedemonte E., Alfonso G.C., Dondero G., De C.F., and Araimo L. Correlation between morphology and stress strain properties of three block copolymers. 2. The hardening effect of the second deformation. Polymer, 18, 191, 1977. 

Antony, P., Puskas, J.E., Ott, H., Altstadt, V., Kovar, M., and Norton, P.R. Effect of Hard and Soft Segment Composition on the Morphology and Mechanical Properties of Polystyrene-Polyisobutylene Thermoplastic Elastomeric Block Copolymers. Proceedings of the Polymer Processing Society Meeting, May 21-24, Montreal, Canada, 2001. 

It was the objective of this work to investigate the effect of variation in block architecture (number and the order of the blocks) on the crystallinity level, morphology, the stress-strain and hysteresis behavior of this series of polymers. In addition, the composition ratio of the two block types is expected to play a crucial role in determining the bulk material properties of the block copolymers. This is related to the fact that the mechanical properties of block copolymer are typically influenced more substantially by the behavior of the continuous phase, as will be demonstrated.(1,22)... 

In order to probe the effect of junction point functionality on chain conformation and morphology of miktoarm star block copolymer architectures, a series of PI PS (n = 2, 4, 16) was synthesized [166]. A single batch of both living PS and PI arms have been used, in order to ensure that all chemically identical arms (either A or B) have the same molecular weights. The living A and B chains were reacted with the appropriate chlorosilane, under appropriate experimental conditions, to produce the corresponding //-stars, as shown in Scheme 88. 

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