Randomly cross-linked poly

Experimental determinations of the contributions above those predicted by the reference phantom network model have been controversial. Experiments of Rennar and Oppermann [45] on end-linked PDMS networks, indicate that contributions from trapped entanglements are significant for low degrees of endlinking but are not important when the network chains are shorter. Experimental results of Erman et al. [46] on randomly cross-linked poly(ethyl acrylate)... 

The quantities B, and g, are given by Eq. (18a) and (18b). Fitting stress-strain data at different degrees of swelling by combination of Eq, (33), (34) and (35) enables one to determine x, and (presumed to be equal to Mq). Flory and Erman have performed the fitting by assuming = 1 and have determined x, C and the phantom modulus for randomly cross-linked poly(dimethylsiloxane) (PDMS) networks. These results were recently further exploited by Queslel and Mark. 

Rennar, N. Oppermann, W., Swelling Behavior and Mechanical-Properties of Endlinked Poly(dimethylsiloxane) Networks and Randomly Cross-Linked Polyisoprene Networks. Coll. Polym. Sci. 1992,270(6), 527-536. 

In earlier work preformed polymer was cross-linked, e.g. by ionizing radiation (39, 103, 104) with suitable assumptions as to randomness of the reaction, the molecular statistics of product can be calculated as a function of the degree of cross-linking. An alternative method is to co-polymerize with small amounts of tetra-functional monomer, e.g. divinyl benzene (36, 105, 107). Both these methods produce highly poly-disperse products, having tetra-functional branch-points. 

An effective polymer catalyst with protease activity has been obtained simply by attaching imidazoles randomly to poly(chloromethylstyrene-co-divinylbenzcnc) (PCD). This polymer is a cross-linked polystyrene (PS) with the styryl moiety being chloro-methylated. Imidazole was attached to PCD through either C-2 or the N atom [44]. Unreacted chloro groups of PCD were blocked by treatment with methoxide. In the best catalyst we obtained ([Imc]22PCD) imidazole was attached to PCD via C-2 and the content of imidazole was 22 residue mol%. 

Poly[(trifluoroethoxy) (octafluoropentoxy) (X)phosphazene] (X — cross-link site) PFAP(II), undergoes a loss in molecular weight at elevated temperatures (135°-200°C) that is detrimental to mechanical properties. The mechanism of molecular weight loss was found to be random chain scission at weak links in the PFAP(II) chain. These weak links are postulated to be phosphazane moieties which would be attacked by water, acids, and POH to produce PN chain scission. 

Ikegami and co-workers have prepared assembled complexes of palladium and a non-cross-linked amphiphilic polymer (Scheme 64).The material, denoted as PdAS, was prepared by reaction of (NH4)2PdCl4 with poly-[iV-isopropylacrylamide)-fo-(4-diphenylstyrylphosphine)], itself made by random co-polymerization of 4-diphenyl-... 

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