Copolymers supermolecular structure

In this review we first summarize methods of synthesis of ECM analogs as graft copolymers. The modification of supermolecular structure (crystallinity, crosslink density, porosity) is then discussed. Finally, the relationships between polymer structure and biologic activity are summarized. 

In liquid crystals or LC-glasses one looks for orientational order and an absence of three-dimensional, long-range, positional order. In liquid crystals, large scale molecular motion is possible. In LC-glasses the molecules are fixed in position. The orientational order can be molecular or supermolecular. If the order rests with a supermolecular structure, as in soap micelles and certain microphase separated block copolymers, the molecular motion and geometry have only an indirect influence on the overall structure of the material. 

Some interesting results have been obtained by Russian scientists [320, 321] who studied the influence of composition inhomogeneity on some service properties and supermolecular structures of copolymers. Two samples of copolymers of butyl acrylate with methacrylic acid were synthesized which had a similar average... 

Varga J. (1995). Crystallization, melting and supermolecular structure of isotactic polypropylene. In Polypropylene Structure, Blends and Composities Structure and Morphology Copolymers and Blends Composites, Karger-Kocsis, J., pp. 56-115, Chapman Hall, ISBN 9780412614309, London. 

Chowdhury, F., Haigh, J.A., Mandelkem, L. and Alamo, R.G. (1998) The supermolecular structure of ethylene-vinyl acetate copolymers. Polymer Bulletin 41,463-470. 

Also the interfacial layer between the homopolymers differs in A/B - - A-block-B blends from that in A/B - - A-block-B blends. In blends compatibilized with block copolymers having the corresponding blocks miscible with the blend components, they are supposed to be molecularly dispersed to a high degree at the A/B interface (Figs. 9,3). In A/B/A-block-B blends, block copolymers with short A blocks are localized at the A/B interface as well, but they do not lose their ordered supermolecular structure (Fig. 10). Block copolymers having long A blocks are... 

The stability of these complexes is a problem that needs further investigation. For example, when a complex of PVP formed with the aqueous disodium salt of the copolymer of isophthalic acid and 4,4 -diamino-2,2 -disulfobiphenyl was treated with sodium chloride, the PVP was gradually ejected from the complex until a supermolecular structure was formed which contained no PVP [96]. 

The information on the structure of the cholesteric mesophase of polymers is currently limited to data on cholesteric polymers of the comb-shaped type. The comb-shaped structure of macromolecules with mesogenic side groups determines their tendency to form layered structures. In this respect, the question arises of how the helical supermolecular structure is formed in such a system and what its features are in comparison to the cholesteric structure of low-molecular-weight liquid crystals. The answer to this question is given in [81, 82], where the structure of homopolymers and copolymers forming the cholesteric mesophase was studied. 

FaiUa MD, Lucas JC, Mandelkern L Supermolecular structure of random copolymers of ethylene, Macromolecules 27(6) 1334—1337, 1994. 

The morphological or supermolecular structure of fibrous cellulose is easily altered by formation of graft copolymers. The distribution of copolymer within the fibrous cellulose primarily depends on... 

It is well known that the addition of a component soluble in each of the phases of a polymer blend has a stabilizing effect. Hence, the modification of a copolymer chain by an additional block can produce a similar effect, ie., stabilization of the biphase supermolecular structure on the nano-level. The knowledge of the solubility parameters of the blocks allows the prediction of a critical degree of polymerization (DP) of the respective blocks (the maximum DP, at which the blocks dissolve in each other). The data presented in Table 2 show that the blocks PBT and PA12 are mutually soluble within the DP range of 1 12. The PA12 block with the molecular weight of 2000 g/mole (DP = 1) is insoluble in the P04 phase, whereas the PBT block dissolves in this phase when its DP < 3. 

The incorporation of a third block into the main chain of a multiblock copolymer not only changes its chemical structure, but also influences its morphology [31]. The changes in the supermolecular structure depend on the solubility of the additional block in the amorphous phases of the two other blocks. This solubility is affected by the chemical structure, molecular weight, polydispersity and the contribution of each of the blocks in the terpolymer (Figure 15). The thermoplastic elastomers of the -(4GT- -P04- -PA12)- type have a nanostructure and possess useful properties when the molecular weights of the blocks are appropriately chosen 1500 < 2500 g/mole, 1000 < < 1500 g/mole,... 

Abstract The optical achvities of poly-(R)-lactide, poly-(S)-lactide, poly(beta -hydroxybutyrate) and two beta -hydroxyvalerate copolymers were measured in soluhon, as solid powders in suspension, and where possible, as films. Poly-(plus)-3-methyl-I-pentene was also reinvestigated. In some cases the specific rotahon values of powder samples showed significant differences from the values of the solution measurements. The discrepancies of the data observed seem to reflect the local environment of the polymer chains in supermolecular assemblies and consequently the sohd state structure (morphology) of the polymers. The circular dichroism (CD) spectra of the polymers were also measured in solution and in the form of their films. For comparison, the CD spectra of the namrally occurring protein casein and of the synthetic polypeptide poly-(i-)-proline were also measured. (Author abstract) 2 I Refs. 

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