Effect of different monomer precursors with identical functionality on the properties of the polymer network

Abstract

The association between thermo-mechanical properties in polymers and functionality of monomer precursors is frequently exploited in the materials science. However, it is not known if there are more variables beyond monomer functionality that have a similar link. Here, by using simulations to generate spatial networks from chemically different monomers with identical functionality we show that such networks have universal graph-theoretical properties as well as a near-universal elastic modulus. The vitrification temperature was found to be universal only up to a certain network density, as measured by the bond conversion. The latter observation is explained by the fact that monomer’s tendency to coil enhances formation of topological holes, which, when accumulated, amount to a percolating cell complex restricting network’s mobility. This higher-order percolation occurs late after gelation and is shown to coincide with the onset of brittleness, as indicated by a sudden increase in the glass transition temperature.

Decoding Elasticity Build-Up and Network Topology in Free-Radical Cross-Linking Polymerization: A Combined Experimental and Atomistic Approach

“…A marked enhancing effect was demonstrated for the glasstransition temperature beyond this point. 30 The simulated structures at p = 0.9 and 1.0 were additionally subjected to a uniaxial tensile deformation in order to probe the effect of the fluctuation level of the network junctions on the elastic response of the strands. The average strand length increases linearly with the strain for both conversion degrees.…”

“…Independently, computational schemes were elaborated over time and could be implemented to investigate the equilibrium topology of networks generated by a free-radical mechanism and later to predict the density, the glass transition, and mechanical properties. − In addition, topological details such as the density of the elastically effective network strands can be extracted from molecular simulations, which so far can merely be estimated approximately from experimental data within the framework of the classical statistical models . Recently, Zhong et al proposed the real elastic network theory (RENT) that accounts for the effect of topological defects on the bulk elasticity of polymer hydrogels.…”

Isolating Chemical Reaction Mechanism as a Variable with Reactive Coarse-Grained Molecular Dynamics: Step-Growth versus Chain-Growth Polymerization

“…Many contemporary polymer simulations focus on a specific polymer or class of polymers, − and we use similar analytical approaches to investigate and validate the work presented here. However, the methodology we introduce with the UM approach is more closely related to studies where researchers systematically disabled components of MD force fields.…”

Sequential construction of spatial networks with arbitrary degree sequence and edge length distribution

“…To mention examples, spatial networks are ubiquitous in soft materials and polymer gels, where vertices represent correspondingly monomer units and granules [7,8]. Likewise, in wireless communication the vertices are receivers/transmitters distributed on a plane and the edges represent neighbours at a close distance [9,4].…”