Molecular dynamics simulations of a coarse-grained bead-spring model of ring polymer brushes under compression are presented. Flexible polymer brushes are always disordered during compression, whereas semiflexible polymer brushes tend to be ordered under sufficiently strong compression. Further, the polymer monomer density of the semiflexible polymer brush is very high near the brush surface, inducing a peak value of the free energy near the surface. Therefore, when nanoparticles are compressed in semiflexible ring polymer brushes, they tend to exhibit a closely packed single-layer structure between the brush surface and the impenetrable wall, and a quasi-two-dimensional ordered structure near the brush surface is formed under strong compression. These findings provide a new approach to designing responsive applications.
M. V. Reddy, T. Yu, C. H. Sow, Z. X. Shen, C. T. Lim, G. V. S. Rao, and B. V. R. Chowdari, α-Fe2O3 nanoflakes as an anode material for Li-ion batteries, Adv. Funct. Mater. 17(7), 2792 (2006)
2
T. Yu, Y. W. Zhu, X. J. Xu, Z. X. Shen, P. Chen, C.T. Lim, J. T. L. Thong, and C. H. Sow, Controlled growth and field-emission properties of cobalt oxide nanowalls, Adv. Mater. 17(13), 1595 (2005)
https://doi.org/10.1002/adma.200500322
3
X. D. Gao, X. M. Li, W. D. Yu, F. Peng, and C. Y. Zhang, Oversized hexagonal nanosheets of layered zinc hydroxysulfates via the hexamethylenetetraminemediated solution route, Mater. Res. Bull. 41(3), 608 (2006)
https://doi.org/10.1016/j.materresbull.2005.09.001
4
X. Huang, S. Tang, X. Mu, Y. Dai, G. Chen, Z. Zhou, F. Ruan, Z. Yang, and N. Zheng, Freestanding palladium nanosheets with plasmonic and catalytic properties, Nat. Nanotechnol. 6(1), 28 (2011)
https://doi.org/10.1038/nnano.2010.235
5
H. L. Wang, H. S. Casalongue, Y. Y. Liang, and H. J. Dai, NiOH2 nanoplates grown on graphene as advanced electrochemical pseudocapacitormaterials, J. Am. Chem. Soc. 132(21), 7472 (2010)
https://doi.org/10.1021/ja102267j
6
S. H. Chen and D. L. Carroll, Silver nanoplates: Size control in two dimensions and formation mechanisms, J. Phys. Chem. B 108(18), 5500 (2004)
https://doi.org/10.1021/jp031077n
7
X. P. Sun, S. J. Dong, and E. Wang, Large-scale synthesis of micrometer- scale single-crystalline Au plates of nanometer thickness by a wet-chemical route, Angew. Chem. Int. Ed. 43(46), 6360 (2004)
https://doi.org/10.1002/anie.200461013
M. Q. Yang, N. Zhang, M. Pagliaro, and Y. J. Xu, Artificial photosynthesis over graphene-semiconductor composites: Are we getting better? Chem. Soc. Rev. 43(24), 8240 (2014)
https://doi.org/10.1039/C4CS00213J
10
S. Z. Butler, S. M. Hollen, L. Cao, Y. Cui, J. A. Gupta, , Challenges and opportunities in two-dimensional materials beyond graphene, ACS Nano 7(4), 2898 (2013)
https://doi.org/10.1021/nn400280c
11
J. Yu, Y. Yu, P. Zhou, W. Xiao, and B. Cheng, Morphology dependent photocatalytic H2-production Activity of CdS, Appl. Catal. B 184(2), 156 (2014)
https://doi.org/10.1016/j.apcatb.2014.03.013
12
F. Dong, L. Wu, Y. Sun, M. Fu, Z. Wu, and S. C. Lee, Efficient synthesis of polymeric g-C3N4 layered materials as novel efficient visible light driven photocatalysts, J. Mater. Chem. 21(39), 15171 (2011)
https://doi.org/10.1039/c1jm12844b
13
J. Hong, Y. Wang, Y. Wang, W. Zhang, and R. Xu, Noble-metal-free NiS/C3N4 for efficient photocatalytic hydrogen evolution from water, ChemSusChem 6(12), 2263 (2013)
https://doi.org/10.1002/cssc.201300647
14
X. Song, J. Hu, and H. Zeng, Two-dimensional semiconductors: Recent progress and future perspectives, J. Mater. Chem. 1, 2952 (2013)
https://doi.org/10.1039/c3tc00710c
15
S. Khanchandani, S. Kundu, A. Patra, and A. K. Ganguli, Shell thickness dependent photocatalytic properties of ZnO/CdS core-shell nanorods, J. Phys. Chem. C 116(44), 23653 (2012)
https://doi.org/10.1021/jp3083419
16
Y. Xu, W. Zhao, R. Xu, Y. Shi, and B. Zhang, Synthesis of ultrathin CdS nanosheets as efficient visiblelight- driven water splitting photocatalysts for hydrogen evolution, Chem. Commun. 49(84), 9803 (2013)
https://doi.org/10.1039/c3cc46342g
17
Y. Yu, P. Zhang, L. Guo, Z. Chen, Q. Wu, Y. Ding, W. Zheng, and Y. Cao, The design of TiO2 nanostructures (nanoparticle, nanotube, and nanosheet) and their photocatalytic activity, J. Phys. Chem. C 118(24), 12727 (2014)
https://doi.org/10.1021/jp500252g
18
I. Y. Kim, Y. K. Jo, J. M. Lee, L. Wang, and S. J. Hwang, Unique advantages of exfoliated 2D nanosheets for tailoring the functionalities of nanocomposites, J. Phys. Chem. Lett. 5(23), 4149 (2014)
https://doi.org/10.1021/jz502038g
19
T. Sagawa, S. Yoshikawa, and H. Imahori, Onedimensional nanostructured semiconducting materials for organic photovoltaics, J. Phys. Chem. Lett. 1(7), 1020 (2010)
https://doi.org/10.1021/jz100065u
20
L. Yuan, M. Q. Yang, and Y. J. Xu, Tuning the surface charge of graphene for self-Assembly synthesis of a SnNb2O6 nanosheet-graphene (2D-2D) nanocomposite with enhanced visible light photoactivity, Nanoscale 6(12), 6335 (2014)
https://doi.org/10.1039/c4nr00116h
A. Halperin, M. Tirrell, and T. P. Lodge, Tethered chains in polymer microstructures, Adv. Polym. Sci. 100, 31 (1992)
https://doi.org/10.1007/BFb0051635
R. C. Advincula, W. J. Brittain, K. C. Caster, and J. Rühe, Polymer Brushes, Weinheim: Wiley VCH, pp 427–440 (2004)
https://doi.org/10.1002/3527603824
25
G. S. Grest and K. Kremer, Molecular dynamics simulation for polymers in the presence of a heat bath, Phys. Rev. A 33(5), 3628 (1986)
https://doi.org/10.1103/PhysRevA.33.3628
26
A. Brasiello, S. Crescitelli, and G. Milano, Development of a coarse-grained model for simulations of tridecanoin liquid-solid phase transitions, Phys. Chem. Chem. Phys. 13(37), 16618 (2011)
https://doi.org/10.1039/c1cp20604d
27
T. Carlsson, N. Kamerlin, G. A. Arteca, and C. Elvingson, Brownian dynamics of a compressed polymer brush model: Off-equilibrium response as a function of surface coverage and compression rate, Phys. Chem. Chem. Phys. 13(35), 16084 (2011)
https://doi.org/10.1039/c1cp21433k
28
I. G. Elliott, T. L. Kuhl, and R. Faller, Molecular simulation study of the structure of high density polymer brushes in good solvent, Macromolecules 43(21), 9131 (2010)
https://doi.org/10.1021/ma101252c
Y. F. Hua, L. X. Zhang, and L. Zhang, Compressiondriven migration of nanoparticles in semiflexible polymer brushes, Polymer 83(9), 67 (2016)
https://doi.org/10.1016/j.polymer.2015.12.003
32
A. Milchev and K. Binder, Unconventional ordering behavior of semi-flexible polymers in dense brushes under compression, Soft Matter 10(21), 3783 (2014)
https://doi.org/10.1039/c3sm53133c
33
G. M. Torrie and J. P. Valleau, Nonphysical sampling distributions in Monte Carlo free-energy estimation: Umbrella sampling, J. Comput. Phys. 23(2), 187 (1977)
https://doi.org/10.1016/0021-9991(77)90121-8