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Li YC, Wu ZP, Zong ZH, Cao XZ. Rheological Role of Stiff Nanorings on Concurrently Strengthening and Toughening Polymer Nanocomposites. ACS Macro Lett 2023; 12:183-188. [PMID: 36692488 DOI: 10.1021/acsmacrolett.2c00610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Nanorings, which are increasingly uncovered in natural systems and synthesized in man-made materials, exhibit dynamics distinct from those known for linear chains. We show in this study that, when immersed in a polymer melt matrix, segments of a stiff nanoring (SNR) have more facilitated subdiffusion, i.e., with a larger scaling exponent in the mean squared displacement, than those belonging to one flexible counterpart, while the whole SNR is more suppressed by its surroundings. It is revealed that adding SNRs contributes to achieving the long-anticipated rheological objective of sol- and gel-like characteristics at high and low shearing frequencies, respectively. This study suggests the promising prospect of exploiting SNRs to concurrently strengthen and toughen target polymer nanocomposites.
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Affiliation(s)
- Yu-Chao Li
- Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, P.R. China
| | - Zong-Pei Wu
- Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, P.R. China
| | - Ze-Hao Zong
- Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, P.R. China
| | - Xue-Zheng Cao
- Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, P.R. China
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Chen Y, Xu H, Ma Y, Liu J, Zhang L. Diffusion of polymer-grafted nanoparticles with dynamical fluctuations in unentangled polymer melts. Phys Chem Chem Phys 2022; 24:11322-11335. [PMID: 35485911 DOI: 10.1039/d2cp00002d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The dynamics of polymer-grafted nanoparticles (PGNPs) in melts of unentangled linear chains were investigated by means of coarse-grained molecular dynamics simulations. The results demonstrated that the graft monomers closer to the particle surface relax more slowly than those farther away due to the constraint of the grafted surface and the confinement of the neighboring chains. Such heterogeneous relaxations of the surrounding environment would perturb the particle motion, making them fluctuating around their centers before they can diffuse through the melt. During such intermediate-time stage, the dynamics is subdiffusive while the distribution of particle displacements is Gaussian, which can be described by the popular fractional Brownian motion model. For the long-time Fickian diffusion, we found that the diffusivity D decreases with increasing grafting density Σg, grafted chain length Ng, and matrix chain length Nm. This is due to the fact that the diffusivity is controlled by the viscous drag of an effective core, consisting of the NP and the non-draining layer of graft segments, and that of the free-draining graft layer outside the "core". With increasing Σg, the PGNPs become harder with greater effective size and thinner free draining layer, resulting in a reduction in D. At extremely high Σg, the diffusivity can even be estimated by the diameter-renormalized Stokes-Einstein (SE) relation. With increasing Ng, both the effective core size and the thickness of the free-draining layer increase, leading to a reduction in diffusivity by D ∼ N-γg with 0.5 < γ < 1. Increasing Nm would lead to the enlargement of the effective core size but meanwhile result in the reduction of the free-draining layer thickness due to autophobic dewetting. The counteraction between these two opposite effects leads to only a slight reduction in the diffusivity, significantly different from the typical SE behavior where D ∼ Nm-1. These findings bear significance in unraveling the fundamental physics of the anomalous dynamics of PGNPs in various polymers, including biological and synthetic.
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Affiliation(s)
- Yulong Chen
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
| | - Haohao Xu
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
| | - Yangwei Ma
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
| | - Jun Liu
- Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, China.
| | - Liqun Zhang
- Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, China.
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Hoogenboom BW, Hough LE, Lemke EA, Lim RYH, Onck PR, Zilman A. Physics of the Nuclear Pore Complex: Theory, Modeling and Experiment. PHYSICS REPORTS 2021; 921:1-53. [PMID: 35892075 PMCID: PMC9306291 DOI: 10.1016/j.physrep.2021.03.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The hallmark of eukaryotic cells is the nucleus that contains the genome, enclosed by a physical barrier known as the nuclear envelope (NE). On the one hand, this compartmentalization endows the eukaryotic cells with high regulatory complexity and flexibility. On the other hand, it poses a tremendous logistic and energetic problem of transporting millions of molecules per second across the nuclear envelope, to facilitate their biological function in all compartments of the cell. Therefore, eukaryotes have evolved a molecular "nanomachine" known as the Nuclear Pore Complex (NPC). Embedded in the nuclear envelope, NPCs control and regulate all the bi-directional transport between the cell nucleus and the cytoplasm. NPCs combine high molecular specificity of transport with high throughput and speed, and are highly robust with respect to molecular noise and structural perturbations. Remarkably, the functional mechanisms of NPC transport are highly conserved among eukaryotes, from yeast to humans, despite significant differences in the molecular components among various species. The NPC is the largest macromolecular complex in the cell. Yet, despite its significant complexity, it has become clear that its principles of operation can be largely understood based on fundamental physical concepts, as have emerged from a combination of experimental methods of molecular cell biology, biophysics, nanoscience and theoretical and computational modeling. Indeed, many aspects of NPC function can be recapitulated in artificial mimics with a drastically reduced complexity compared to biological pores. We review the current physical understanding of the NPC architecture and function, with the focus on the critical analysis of experimental studies in cells and artificial NPC mimics through the lens of theoretical and computational models. We also discuss the connections between the emerging concepts of NPC operation and other areas of biophysics and bionanotechnology.
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Affiliation(s)
- Bart W. Hoogenboom
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom
| | - Loren E. Hough
- Department of Physics and BioFrontiers Institute, University of Colorado, Boulder CO 80309, United States of America
| | - Edward A. Lemke
- Biocenter Mainz, Departments of Biology and Chemistry, Johannes Gutenberg University and Institute of Molecular Biology, 55128 Mainz, Germany
| | - Roderick Y. H. Lim
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, 4056 Basel, Switzerland
| | - Patrick R. Onck
- Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Anton Zilman
- Department of Physics and Institute for Biomedical Engineering (IBME), University of Toronto, Toronto, ON M5S 1A7, Canada
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Cao XZ, Merlitz H, Wu CX, Forest MG. Chain stiffness boosts active nanoparticle transport in polymer networks. Phys Rev E 2021; 103:052501. [PMID: 34134347 DOI: 10.1103/physreve.103.052501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/27/2021] [Indexed: 11/07/2022]
Abstract
Recent advances in technologies such as nanomanufacturing and nanorobotics have opened new pathways for the design of active nanoparticles (NPs) capable of penetrating biolayers for biomedical applications, e.g., for drug delivery. The coupling and feedback between active NP motility (with large stochastic increments relative to passive NPs) and the induced nonequilibrium deformation and relaxation responses of the polymer network, spanning scales from the NP to the local structure of the network, remain to be clarified. Using molecular dynamics simulations, combined with a Rouse mode analysis of network chains and position and velocity autocorrelation functions of the NPs, we demonstrate that the mobility of active NPs within cross-linked, concentrated polymer networks is a monotonically increasing function of chain stiffness, contrary to passive NPs, for which chain stiffness suppresses mobility. In flexible networks, active NPs exhibit a behavior similar to passive NPs, with a boost in mobility proportional to the self-propulsion force. These results are suggestive of design strategies for active NP penetration of stiff biopolymer matrices.
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Affiliation(s)
- Xue-Zheng Cao
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
| | - Holger Merlitz
- Leibniz-Institut für Polymerforschung Dresden, 01069 Dresden, Germany
| | - Chen-Xu Wu
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
| | - M Gregory Forest
- Departments of Mathematics, Applied Physical Sciences, Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3250, USA
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Bailey EJ, Winey KI. Dynamics of polymer segments, polymer chains, and nanoparticles in polymer nanocomposite melts: A review. Prog Polym Sci 2020. [DOI: 10.1016/j.progpolymsci.2020.101242] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Chen Y, Ma R, Qian X, Zhang R, Huang X, Xu H, Zhou M, Liu J. Nanoparticle Mobility within Permanently Cross-Linked Polymer Networks. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00334] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Yulong Chen
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Rui Ma
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Xin Qian
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Ruoyu Zhang
- Key Laboratory of Bio-based Polymeric Materials Technology and Application of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Xifu Huang
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
- Ningbo Detai Chemical Co., Ltd., Ningbo 315204, China
| | - Haohao Xu
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Mi Zhou
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Jun Liu
- Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029, China
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Park J, Bailey EJ, Composto RJ, Winey KI. Single-Particle Tracking of Nonsticky and Sticky Nanoparticles in Polymer Melts. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00457] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Jinseok Park
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Eric J. Bailey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Russell J. Composto
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Karen I. Winey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Cao XZ, Merlitz H, Forest MG. Nanoparticle Loading of Unentangled Polymers Induces Entanglement-Like Relaxation Modes and a Broad Sol-Gel Transition. J Phys Chem Lett 2019; 10:4968-4973. [PMID: 31386385 DOI: 10.1021/acs.jpclett.9b01954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We combine molecular dynamics simulations, imaging and data analysis, and the Green-Kubo summation formula for the relaxation modulus G(t) to elicit the structure and rheology of unentangled polymer-nanoparticle composites distinguished by small NPs and strong NP-monomer attraction, εNPM ≫ kBT. A reptation-like plateau emerges in G(t) beyond a terminal relaxation time scale as the volume fraction, cNP, of NPs increases, coincident with a structure transition. A condensed phase of NP-aggregates forms, tightly interlaced with thin sheets of polymer chains, the remaining phase consisting of free chains void of NPs. Rouse mode analyses are applied to the two individual phases, revealing that long-wavelength Rouse modes in the aggregate phase are the source of reptation-like relaxation. Imaging reveals chain motion confined within the thin sheets between NPs and exhibits a 2D analogue of classical reptation. In the NP-free phase, Rouse modes relax indistinguishable from a neat polymer melt. The Fourier transform of G(t) reveals a sol-gel transition across a broad frequency spectrum, tuned by cNP and εNPM above critical thresholds, below which all structure and rheological transitions vanish.
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Affiliation(s)
- Xue-Zheng Cao
- Departments of Mathematics and Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3250, United States
- Department of Physics, Xiamen University, Xiamen 361005, P.R. China
| | - Holger Merlitz
- Leibniz-Institut für Polymerforschung Dresden, 01069 Dresden, Germany
| | - M Gregory Forest
- Departments of Mathematics and Applied Physical Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3250, United States
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Li SJ, Qian HJ, Lu ZY. A simulation study on the glass transition behavior and relevant segmental dynamics in free-standing polymer nanocomposite films. SOFT MATTER 2019; 15:4476-4485. [PMID: 31111851 DOI: 10.1039/c9sm00267g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In polymer/nanoparticle composite (PNC) thin films, polymer chains experience strong confinement effects not only at the free surface area but also from nanoparticles (NPs). In this work, the influence of NP-polymer interaction and NP distribution on the polymer segmental dynamics and the glass transition behavior of PNC free-standing films are investigated through molecular dynamics simulations. We demonstrate that NPs will migrate to the film surface area and form an NP-concentrated layer when NP-polymer interactions are weak, while NPs are well dispersed in the bulk region when NP-polymer interactions are strong. In both cases, we find increases in the glass transition temperature Tg compared with the pure film without NPs, although with a different degree. The weakly interacting system has the same Tg as the pure bulk system without NPs. The NP layer formed at the surface area reduces both the mobility of the surface polymer beads and the mobility gradient in the film normal direction (MGFND), therefore resulting in an increase in the Tg which highlights the vital role of the mobile surface layer. In contrast, the NPs in the bulk region enlarge the MGFND. NPs have opposite influences on the polymer bead dynamic anisotropy when they interact weakly or strongly with polymers, weakened for the former and enhanced for the latter. These findings offer a clear picture of the segmental dynamics and glass transition behavior in free-standing PNC films with different NP-polymer interaction strengths. We hope these results will be helpful for the property design of related materials.
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Affiliation(s)
- Shu-Jia Li
- State Key Laboratory of Supramolecular Structure and Materials, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130021, China.
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Chen Y, Xu Q, Jin Y, Qian X, Ma R, Liu J, Yang D. Shear-induced parallel and transverse alignments of cylinders in thin films of diblock copolymers. SOFT MATTER 2018; 14:6635-6647. [PMID: 29999081 DOI: 10.1039/c8sm00833g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Coarse-grained Langevin dynamics simulations were performed to investigate the alignment behavior of monolayer films of cylinder-forming diblock copolymers under steady shear, a structure of significant importance for many technical applications such as nanopatterning. The influences of shear conditions, the interactions involved in the films, and the initial morphology of the cylinder-forming phase were examined. Our results showed that above a critical shear rate, the cylinders can align either along the shearing direction or transverse (log-rolling) to the shearing direction depending on the relative strength between the interchain attraction in the cylinders (εAA) and the surface attraction of the confining walls with the film (εBW). To understand the underlying mechanism, the microscopic properties of the films under shear were systematically investigated. It was found that at low εAA/εBW, the majority blocks of the diblock polymer that are adsorbed on the confining walls prefer to move synchronously with the walls, inducing the cylinder-forming blocks to align along the flow direction. When εAA/εBW is above a threshold value, a strong attraction between the cylinder-forming blocks restrains their movement during shear, leading to the log-rolling motions of the cylinders. To predict the threshold εAA/εBW, we developed an approach based on equilibrium thermodynamics data and found good agreement with our shear simulations.
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Affiliation(s)
- Yulong Chen
- College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
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Li SJ, Qian HJ, Lu ZY. Translational and rotational dynamics of an ultra-thin nanorod probe particle in linear polymer melts. Phys Chem Chem Phys 2018; 20:20996-21007. [DOI: 10.1039/c8cp03653e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Translational and rotational dynamics of a single rigid ultra-thin nanorod probe particle in linear polymer melts are investigated using coarse-grained molecular dynamics (CG-MD) simulations.
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Affiliation(s)
- Shu-Jia Li
- State Key Laboratory of Supramolecular Structure and Materials
- Laboratory of Theoretical and Computational Chemistry
- International Joint Research Laboratory of Nano-Micro Architecture Chemistry
- Institute of Theoretical Chemistry
- Jilin University
| | - Hu-Jun Qian
- State Key Laboratory of Supramolecular Structure and Materials
- Laboratory of Theoretical and Computational Chemistry
- International Joint Research Laboratory of Nano-Micro Architecture Chemistry
- Institute of Theoretical Chemistry
- Jilin University
| | - Zhong-Yuan Lu
- State Key Laboratory of Supramolecular Structure and Materials
- Laboratory of Theoretical and Computational Chemistry
- International Joint Research Laboratory of Nano-Micro Architecture Chemistry
- Institute of Theoretical Chemistry
- Jilin University
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12
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Yang H, Cao XZ, Zhou B, Liu YS, Wu CX. Adding Nonconnected Monomers to Manage the Layering Crystallization of Polymers on Athermal Substrate. MACROMOL THEOR SIMUL 2017. [DOI: 10.1002/mats.201700068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Huan Yang
- Department of Physics; Zhejiang Sci-Tech University; Hangzhou 310018 P. R. China
| | - Xue-Zheng Cao
- Department of Physics; Zhejiang Sci-Tech University; Hangzhou 310018 P. R. China
- Department of Chemistry; University of North Carolina at Chapel-Hill; Chapel-Hill NC 27514 USA
| | - Bin Zhou
- Department of Physics; Zhejiang Sci-Tech University; Hangzhou 310018 P. R. China
| | - Yong-Song Liu
- Department of Physics; Zhejiang Sci-Tech University; Hangzhou 310018 P. R. China
| | - Chen-Xu Wu
- Department of Physics; Xiamen University; Xiamen 361005 P. R. China
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