Entanglements in polymer nanocomposites containing spherical nanoparticles

Karatrantos, Argyrios; Clarke, Nigel; Composto, Russell J.; Winey, Karen I.

doi:10.1039/c5sm02010g

Cited by 65 publications

(73 citation statements)

References 76 publications

(126 reference statements)

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“…) are of size about or smaller than the tube diameter of the dilated PS/POSS # ‐sty network. Hence, there is chain intercalation promoted by the increase of free volume and therefore chain disentanglement, a result also reported for small nanoparticles dispersed in a polymer matrix .…”

Section: Resultssupporting

confidence: 62%

Co‐(POSS#‐styrene) nanocomposites reduced the glass‐transition temperature, rubbery modulus, and melt viscosity of entangled polystyrene

Romo-Uribe

2019

Polymer Engineering & Sci

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The addition of polyhedral oligomeric silsesquioxane‐styrene copolymers, co(POSS#‐sty), to entangled polystyrene (PS) reduced (1) the glass‐transition temperature, Tg,blend, (2) the rubbery modulus, and (3) the melt viscosity. POSS#‐sty copolymers with # = 15, 25, and 45 wt% POSS were blended with PS. The blends were miscible and Tg,blend decreased with POSS#‐sty content. Strikingly, POSS#‐sty copolymers also reduced the melt viscosity, up to an order of magnitude reduction. The reductions of Tg,blend and melt viscosity were driven by the type of POSS#‐sty copolymer, POSS45‐sty producing the largest decrease of Tg,blend. Linear viscoelasticity and the time–temperature superposition (TTS) principle (using Tref = Tg + 50 K to ensure iso‐frictional conditions) revealed that POSS#‐sty induced up to an order of magnitude reduction of the rubbery modulus Ge. The increase of free volume fg promoted by POSS#‐sty induced the reduction of Tg,blend and Ge, as revealed by TTS analysis. The increase of free volume promoted by POSS#‐sty induced chain intercalation (TEM showed that POSS domains were smaller than the molecular mesh) and these are key factors for the chain disentanglement with the consequent rubbery modulus and melt viscosity reductions. The use of low‐molecular weight polystyrene alone will not produce increase of free volume and tube dilation. POLYM. ENG. SCI., 59:2377–2386, 2019. © 2019 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 62%

Co‐(POSS#‐styrene) nanocomposites reduced the glass‐transition temperature, rubbery modulus, and melt viscosity of entangled polystyrene

Romo-Uribe

2019

Polymer Engineering & Sci

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“…This assumption is usually considered appropriate in the bulk melt but appears questionable for confined systems. Alternative measures for the entanglement length that count the number of kinks in primitive paths which are generated using Kröger's Z1 algorithm 21 have also been investigated under confinement [22][23][24] . One such measure, the 'modified S-kink' estimator, is:…”

Section: Introductionmentioning

confidence: 99%

Entanglement dynamics at flat surfaces: Investigations using multi-chain molecular dynamics and a single-chain slip-spring model

Kirk

Wang

Ilg

2019

The Journal of Chemical Physics

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The dynamics of an entangled polymer melt confined in a channel by parallel plates is investigated by Molecular Dynamics (MD) simulations of a detailed, multi-chain model. A primitive path analysis predicts that the density of entanglements remains approximately constant throughout the gap and drops to lower values only in the immediate vicinity of the surface. Based on these observations, we propose a coarse-grained, single-chain slip-spring model with a uniform density of slip-spring anchors and slip-links. The slip-spring model is compared to the Kremer-Grest MD bead-spring model via equilibrium correlation functions of chain orientations. Reasonably good agreement between the single-chain model and the detailed multi-chain model is obtained for chain relaxation dynamics, both away from the surface and for chains whose center of mass positions are at a distance from the surface that is less than the bulk chain radius of gyration, without introducing any additional model parameters. Our results suggest that there is no considerable drop in topological interactions for chains in the vicinity of a single flat surface. We infer from the slip-spring model that the experimental plateau modulus of a confined polymer melt may be different to a corresponding unconfined system even if there is no drop in topological interactions for the confined case.

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“…Following an approach similar to the one used in previous computational investigations in nanocomposites with impenetrable spheres representing hard nanoparticles, 18,[46][47][48][49] we have determined the entanglement length in our all-polymer nanocomposites by analysing the primitive path (PP) of the polymer chains. The PP is identified as the shortest path between the end monomers of the chain that is compatible with the topological constraints.…”

Section: Introductionmentioning

confidence: 99%

The Role of the Topological Constraints in the Chain Dynamics in All-Polymer Nanocomposites

et al. 2017

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We investigate all-polymer nanocomposites, formed by linear chains and single-chain polymer nanoparticles (SCNPs), by means of large-scale simulations. To distinguish the role of the soft penetrable character of the SCNPs in the topological constraints from other specific contributions present in experiments, the simulations for different compositions of the mixture are performed at constant density, and with identical segmental mobility and monomer excluded volume for the SCNPs and linear chains. Every composition leads to a well-dispersed nanocomposite with fully-penetrated nanofillers. Hence, unlike in the case of hard nanofillers, the SCNPs do not exert confinement effects on the linear chains, and only contribute to the topological constraints. We discuss the intramolecular dynamics of the linear chains in terms of the tube model. We determine the entanglement length of the linear chains by analysing their isoconfigurational mean paths (IMP) and the primitive paths (PP), as a function of the concentration and topology of the SCNPs. In the analysis we use different estimators proposed in the literature. The IMP and PP analysis in the nanocomposites with sparse SCNPs yields values of the entanglement length smaller and larger, respectively, than in the reference pure linear melt, though small variations are observed. A more consistent trend is found in the nanocomposites with globular SCNPs, where both the IMP and PP analysis unambiguously reveal that the linear chains are more entangled than in the pure linear melt. Such differences between the effects of SCNPs with different topologies are presumably related to the much higher fraction of threadable loops in the globular SCNPs, with respect to their sparse counterparts, which effectively lead to more topological constraints.

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Entanglements in polymer nanocomposites containing spherical nanoparticles

Cited by 65 publications

References 76 publications

Co‐(POSS#‐styrene) nanocomposites reduced the glass‐transition temperature, rubbery modulus, and melt viscosity of entangled polystyrene

Co‐(POSS#‐styrene) nanocomposites reduced the glass‐transition temperature, rubbery modulus, and melt viscosity of entangled polystyrene

Entanglement dynamics at flat surfaces: Investigations using multi-chain molecular dynamics and a single-chain slip-spring model

The Role of the Topological Constraints in the Chain Dynamics in All-Polymer Nanocomposites

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