Effect of Polymer Morphology

Enzyme-dependent and chemically derived degradation of polymers, particularly polyesters, were analyzed in-vitro in terms of chemical composition and physical properties. It was observed that the composition of a copolymer corresponding to the lowest melting point is highly susceptible to degradation, while the fastest degradation rates were observed with the lowest packing order. 

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The effect of polymer morphology on membrane structure and conductance has been shown recently. In Ref. 25 hydrogen-based graft-copolymer membranes were compared in terms of morphology and performance to random copolymer membranes with the same ion content. For the hydrated grafted membranes TEM micrographs revealed a picture of a continuous phase-separated network of water-filled channels with diameters of 5 nm. In contrast to that, the random copolymer membranes exhibit a reduced tendency toward microphase separation water is... 

Chu, C.C. and Kizil, Z., 1989. The effect of polymer morphology on the hydrolytic degradation of synthetic absorbable sutures. 3rd International ITV Conference on Biomaterials — Medical Textiles, Stuttgart, W. Germany, June 14—16,1989. 

The importance of hydrophobic binding interactions in facilitating catalysis in enzyme reactions is well known. The impact of this phenomenon in the action of synthetic polymer catalysts for reactions such as described above is significant. A full investigation of a variety of monomeric and polymeric catalysts with nucleophilic sites is currently underway. They are being used to study the effect of polymer structure and morphology on catalytic activity in transacylation and other reactions. 

An effect of network morphology is illustrated by the work of Shen and Tobolsky (ISO). They cross-linked rubbers in the presence of inert diluents such polymerizations tend to promote intramolecular chain loops rather than interchain cross-links. Their polymers had very low stress-relaxation... 

In more recent years, Herman Mark has, as we all know, concentrated more on the effects of heterophase morphology of polymers on their mechanical properties. This has enabled him to set up a useful classification system of the various types of heterogeneities which can occur in polymers, e.g., crystallinity, incompatibility, particulate and fibrous inclusions, etc. and to discuss these in the context of their effect on the mechanical properties. Such an "overview" has again kept Mark in great demand as a speaker. 

Lavorgna, M., Mensitieri, G., Scherillo, G., Shaw, M. T., Swier, S. and Weiss, R. A. 2007. Polymer blend for fuel cells based on SPEKK Effect of cocontinuous morphology on water sorption and proton conductivity. Journal of Polymer Science Part B Polymer Physics 45 395-404. 

Nguyen TQ, Martini IB, Liu J, Schwartz BJ (2000) Controlling interchain interactions in conjugated polymers the effects of chain morphology on exciton-exciton annihilation and aggregation in MEH-PPV films. J Phys Chem B 104 237... 

The Effect of Polymer Surface Morphology on Adhesion and Adhesive Joint Strengths... 

Another study of foamed polymers uses modern physicochemical methods of structure elucidation of gas-filled polymers and more accurate mathematical descriptioa These studies have considerably contributed to the understanding of the general character of the spatial structure of plastic foams. Thus, quantitative estimations of the effect of each morphological parameter (specific gravity, size and shape of ceUs, type of communication between ceUs, cell distributbn in the bulk, etc.), on the properties of a given material could be made. 

The Effect of Polymer Type on Film Morphology. At relatively high polymer concentrations, all types of polymers used, and their blends formed continuous films and provided excellent spectra. Blend composition and the presence or absence of crystallization did not cause Christiansen efiect distortions. However, at concentrations usual for SEC analysis, all polymers showed evidence of not wetting the KBr surface, yielded discontinuous films, and often had poor spectra. These results indicate, with respect to spectral distortions, that the main importance of polymer type is its infiuence on continuous-film formation. 

Carter and coworkers studied how side-chain branching in PFs affects device performance with and without an additional HTL of cross-linkable polymer 2 [ 19]. They found that the device efficiency is affected more by the position of the exciton recombination zone than by variations of polymer morphology induced by side-chain branching, which mainly controls the relative emission between vibrational energy levels and has a minimal effect on polymer charge transport properties. For double-layer devices (ITO/PEDOT PSS/2/3,4, or 5/Ca), a typical brightness of 100 cdm 2 at 0.8 MV cm-1, maximum luminance of 10 000 cd m-2 at 1.5 MV cm x, and device efficiencies between 1.3 and 1.8 cd A 1 for 3 and 5 branching can be achieved. 

The mechanical properties of PAn differ considerably between the electrochemi-cally prepared polymer and that produced from solvent casting. As described earlier, electropolymerized emeraldine salts are highly porous and, consequently, have low mechanical strength. Freestanding films may be prepared electrochemically, but their poor mechanical properties limit their usefulness. In contrast, the polymers made from solution are much less porous and are widely used as freestanding films and fibers. The effect of polymer structures and morphology on PAn mechanical properties are described in the following text. 

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