Sticky Rouse Model and Molecular Dynamics Simulation for Dual Polymer Networks

Abstract

Dual polymer networks with stickers have a reputation for enhanced modulus and toughness. We propose a modified sticky Rouse model (SRM) from the single-chain perspective for permanent and transient dual networks, aiming to find a universal description of associative polymer dynamics. The computational complexity of obtaining the analytical relaxation spectrum is simplified by graph theory, implementing matrix reduction of the Rouse–Zimm matrix based on the symmetry. The analytical relaxation spectrum can also return to the case of linear polymers and permanent networks. The modified SRM for dual polymer networks predicts a Rouse-like scale of the linear relaxation modulus G(t) ∝ t –1/2 in sticker relaxation, consistent with the existing experimental results. In particular, the key parameter in the SRM, namely, the effective friction coefficient, can be extracted from the lifetime of sticky bonds and diffusion of chains, obtained by molecular dynamics simulations (MD). Based on that, the SRM model can predict the linear viscoelasticity of dual polymer networks, quantitatively in agreement with our MD results. Our work strongly supports the applicability of the single-chain molecular model SRM for polymer complex networks with reversible associative interactions.

Linear and Nonlinear Viscoelasticities of Dissociative and Associative Covalent Adaptable Networks: Discrepancies and Limits

“…This is actually a core reason that APs are able to analogize entangled polymers, 64,65 which also proves the rationality of describing the network with a single-Gaussian-chain model of SRM in our previous work. 12,15 Furthermore, different from the multimodal distribution of molecular size at high Wi's for entangled polymers, the non-Gaussian behavior is kept within a small range, indicating a hindrance from the network despite sticker dissociation.…”

“…Our previous work on SRM , is an elaborate molecular model, especially for the case of strong association, whose validity has been verified for APs. The purple dashed lines plotted in Figure a,c are the relaxation moduli calculated by SRM with relative frictional coefficient δ = 200 and 3000, respectively.…”

“…Jiang et al , in our group and Ricarte et al proposed the sticky Rouse model to describe the LVE of unentangled APs, which can be well applied to CANs. Shao et al in our group then extended it to a dual-network system. Wu et al and Perego et al , studied the influence of temperature and kinetic activation energy on bond exchange reactions (BERs) of Asso-CANs independently.…”

Linear viscoelasticity, nonlinear rheology and applications of polyethylene terephthalate vitrimers

“…The creep resistance and crosslinking degree were investigated by Qiu's work, confirming excellent processability of PET vitrimers 20 . The theory and simulation study with regard to dynamic network structures have been investigated in detail by our group 32–35 . However, rheology behavior of PET vitrimers in experiments such as different mechanisms in the whole relaxation process, especially nonlinear rheology of vitrimers, has not been explored rigorously so far.…”

“…20 The theory and simulation study with regard to dynamic network structures have been investigated in detail by our group. [32][33][34][35] However, rheology behavior of PET vitrimers in experiments such as different mechanisms in the whole relaxation process, especially nonlinear rheology of vitrimers, has not been explored rigorously so far. Though this PET system is not perfect for research of vitrimer dynamics due to difficulty in characterization of detailed chemical structure, high-performance PET with excellent processability has an enormous potential in industry.…”