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Authors Schwenke, K. ; Lang, M. ; Sommer, J.-U.
Title On the structure of star-polymer networks
Date 12.12.2011
Number 30409
Abstract Using the bond fluctuation model we study polymer networks obtained by endlinking of symmetric 4-arm star polymers. We consider two types of systems. Solutions of one type (A) of star polymers and solution of two types (A, B) of star polymer where A-type polymers can only cross-link with B-type polymers. We find that network defects in A networks are dominated by short dangling loops close to overlap concentration c*. AB networks develop a more perfect network structure, since loop sizes involving an odd number of stars are impossible, and thus, the most frequent dangling loop with largest impact on the phantom modulus is absent. The analysis of the pair-correlation and scattering function reveals that there is an amorphous packing of A and B type stars with a homogenization of A and B concentrations upon cross-linking at intermediate length scales in contrast to the previously suggested crystalline like order of A and B components at c* . This result is corroborated by the coincidence of the probabilities of the shortest loop structures (which is impossible upon the previously suggested packing of stars) in both types of networks. Furthermore, we derive the vector order parameters associated with the most frequent network structures based on the phantom model. In particular, for AB networks we can show that there is a dominating cyclic defect with a clearly separated order parameter that could be used to analyze cyclic network defects.
Publisher Macromolecules
Wikidata Q105744719
Citation Macromolecules 44 (2011) 9464-9472
DOI https://doi.org/10.1021/MA202022Q
Tags monte-carlo diffusion dynamics

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