Field theoretic simulations of polymer nanocomposites

Koski, Jason; Chao, Huikuan; Riggleman, Robert A.

doi:10.1063/1.4853755

Cited by 71 publications

(98 citation statements)

References 86 publications

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“…On top of that the strict enforcement of incompressibility will change the nature of the UV divergence, 45 and so we should not necessarily expect χ e1 (or χ e2 ) to compensate for the UV divergence in the CL-FTS. In any case, more recent CL-FTS have modified the model by smearing the interactions, introducing a finite compressibility and switching to a discrete polymer model in order to avoid the UV divergence; 46 this has also permitted the CL-FTS to handle diblocks of a lower N̅ = 10 5 , although this is still well above the experimental regime.…”

Section: ■ Discussionmentioning

confidence: 99%

Field-Theoretic Simulation of Block Copolymers at Experimentally Relevant Molecular Weights

2015

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Field-theoretic simulation (FTS) offers an efficient means of predicting the equilibrium behavior of high-molecular-weight structured polymers, provided one is able to deal with the strong ultraviolet (UV) divergence that occurs at realistic molecular weights. Here melts of lamellar-forming diblock copolymer are studied using a Monte Carlo version (MC-FTS), where the composition field fluctuates while the pressure field follows the mean-field approximation. We are able to control the UV divergence by introducing a new effective Flory− Huggins interaction parameter, χ e , thereby permitting MC-FTS for molecular weights extending down to values characteristic of experiment. Results for the disordered-state structure function, the layer spacing and compressibility of the ordered lamellar phase, and the position of the order−disorder transition (ODT) show excellent agreement with recent particle-based simulation. Given the immense versatility of FTS, this opens up the opportunity for quantitative studies on a wide range of more complicated block copolymer systems.

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Section: ■ Discussionmentioning

confidence: 99%

Field-Theoretic Simulation of Block Copolymers at Experimentally Relevant Molecular Weights

2015

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“…27,49 Dispersed additives introduce secondary polymer surfaces to composite films, 48 which can influence aging mechanisms throughout the film's core. 49,68,73,74 Like external film surfaces, these interfaces behave as either a constrained or free surface depending on the polymer's adhesion/repulsion to the additive surface.…”

Section: Aging Mechanismsmentioning

confidence: 99%

Physical aging in glassy mixed matrix membranes; tuning particle interaction for mechanically robust nanocomposite films

et al. 2016

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Despite the exceptional separation performance of modern glassy mixed matrix membranes, these materials are not being utilized to improve the performance of existing membrane technologies. Nano-sized additives can greatly enhance separation performance, and have recently been used to overcome age-related performance loss of high performance MMMs. However nano-additives also compromise the structural integrity of films and little is known on how physical aging affects their mechanical properties over time. A solution for both physical aging and mechanical instability is required before these high performance materials can be utilised in industrial membrane applications. Here, we examine physical aging in mixed matrix membranes through mechanical properties and single gas permeation measurements using three glassy polymers, Matrimid® 5218, poly-1-trimethylsilyl-1-propyne (PTMSP), and a Polymer of Intrinsic Microporosity (PIM-1); and a range of nano-scale additives; Silica, PAF-1, UiO-66, and Ti5UiO-66, each previously shown to enhance gas separation performance. We find polymer-additive interactions strongly influence local physical aging and play a key role in determining the overall material properties of glassy nanocomposite films. Strong interface interactions can slow physical aging, and may not correlate to reinforced or age-stable films. Whereas traditionally 'incompatible' nanocomposites exhibit mechanical properties that can improve over time and even outperform their native polymers.Tuning polymer-additive interactions is vital to achieving the physical aging, mechanical stability, and permselectivity requirements of advanced mixed matrix membrane technologies and reducing the enormous global energy cost of separation processes.

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“…Formally such an approach enables one to consider nanoparticles of arbitrary shape and even grafted with polymers but at the same time it increases the computational cost and causes inherent difficulties in the simultaneous solution of partial differential equations and implementation of simulation procedures. 44 As a result, the number of publications on the topic is still very limited. 26,45 A possible simplification here is to fix the phase-separated structure of a diblock copolymer in order to study in detail the spatial distribution and orientational ordering of anisotropic nanoparticles in 5 such a system.…”

Section: Introductionmentioning

confidence: 99%

Ordering of anisotropic nanoparticles in diblock copolymer lamellae: Simulations with dissipative particle dynamics and a molecular theory

Berezkin

Kudryavtsev

Gorkunov

et al. 2017

The Journal of Chemical Physics

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Short title: Ordering of anisotropic nanoparticles: Simulations and theory a) Corresponding author. Electronic mail: yar@ips.ac.ru 2 ABSTRACT Local distribution and orientation of anisotropic nanoparticles in microphase-separated symmetric diblock copolymers has been simulated using dissipative particle dynamics and analyzed with a molecular theory. It has been demonstrated that nanoparticles are characterized by a non-trivial orientational ordering in the lamellar phase due to their anisotropic interactions with isotropic monomer units. In the simulations, the maximum concentration and degree of ordering are attained for nonselective nanorods near the domain boundary. In this case the nanorods have a certain tendency to align parallel to the interface in the boundary region and perpendicular to it inside the domains. Similar orientation ordering of spherical nanoparticles located at the lamellar interface is predicted by the molecular theory which takes into account that the nanoparticles interact with monomer units via both isotropic and anisotropic potentials. Computer simulations enable one to study the effects of the nanorod concentration, length, stiffness, and selectivity of their interactions with the copolymer components on the phase stability and orientational order of nanoparticles. If the volume fraction of the nanorods is lower than 0.1, they have no effect on the copolymer transition from the disordered state into a lamellar microstructure. Increasing nanorod concentration or nanorod length results in clustering of the nanorods and eventually leads to a macrophase separation, whereas the copolymer preserves its lamellar morphology. Segregated nanorods of length close to the width of the diblock copolymer domains are stacked side by side into smectic layers that fill domain space. Thus, spontaneous organization and orientation of nanorods leads to a spatial modulation of anisotropic composite properties creating an opportunity to align block copolymers by external fields which may be important for various applications.

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Field theoretic simulations of polymer nanocomposites

Cited by 71 publications

References 86 publications

Field-Theoretic Simulation of Block Copolymers at Experimentally Relevant Molecular Weights

Field-Theoretic Simulation of Block Copolymers at Experimentally Relevant Molecular Weights

Physical aging in glassy mixed matrix membranes; tuning particle interaction for mechanically robust nanocomposite films

Ordering of anisotropic nanoparticles in diblock copolymer lamellae: Simulations with dissipative particle dynamics and a molecular theory

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