The Formation and Structure of Olympic Gels

TL;DR

This paper investigates the formation and structure of Olympic gels through computer simulations, analyzing different creation methods, and introduces a novel 'progressive construction' technique for gel synthesis.

Contribution

It provides a detailed analysis of Olympic gel formation, including a new single-step construction method and insights into ring formation behavior.

Findings

Pairwise concatenation distribution follows a Poisson distribution.

Enhanced ring formation occurs above overlap concentration, deviating from mean field predictions.

The 'progressive construction' method enables single-step gel formation from concentrated mixtures.

Abstract

Different methods for creating Olympic gels are analyzed using computer simulations. First ideal reference samples are obtained from freely interpenetrating semi-dilute solutions and melts of cyclic polymers. The distribution of pairwise concatenations per cyclic molecule is given by a Poisson-distribution and can be used to describe the elastic structure of the gels. Several batches of linear chains decorated with different selectively binding groups at their ends are mixed in the "DNA Origami" technique and network formation is realized. While the formation of cyclic molecules follows mean field predictions below overlap of the precursor molecules, an enhanced ring formation above overlap is found that is not explained by mean field arguments. The "progressive construction" method allows to create Olympic gels with a single reaction step from a concentrated mixture of large compressed rings with a low weight fraction short chains that are below overlap concentration. This method, however, is limited by the difficulty to obtain a sufficiently high degree of polymerization of the large rings.