title: Glassy dynamics of model colloidal polymers: The effect of "monomer" size.
abstract: In recent years, attempts have been made to assemble colloidal particles into chains, which are termed "colloidal polymers." An apparent difference between molecular and colloidal polymers is the "monomer" size. Here, we propose a model to represent the variation from molecular polymer to colloidal polymer and study the quantitative differences in their glassy dynamics. For chains, two incompatible local length scales, i.e., monomer size and bond length, are manifested in the radial distribution function and intramolecular correlation function. The mean square displacement of monomers exhibits Rouse-like sub-diffusion at intermediate time/length scale and the corresponding exponent depends on the volume fraction and the monomer size. We find that the threshold volume fraction at which the caging regime emerges can be used as a rescaling unit so that the data of localization length versus volume fraction for different monomer sizes can gather close to an exponential curve. The increase of monomer size effectively increases the hardness of monomers and thus makes the colloidal polymers vitrify at lower volume fraction. Static and dynamic equivalences between colloidal polymers of different monomer sizes have been discussed. In the case of having the same peak time of the non-Gaussian parameter, the motion of monomers of larger size is much less non-Gaussian. The mode-coupling critical exponents for colloidal polymers are in agreement with that of flexible bead-spring chains.
authors.affiliation: Department of Physics, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
authors.forename: Bo-Kai
authors.initials: BK
authors.lastname: Zhang
authors.affiliation: Center for Soft Condensed Matter Physics and Interdisciplinary Research, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China.
authors.forename: Hui-Shu
authors.initials: HS
authors.lastname: Li
authors.affiliation: Center for Soft Condensed Matter Physics and Interdisciplinary Research, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Chen
authors.affiliation: Center for Soft Condensed Matter Physics and Interdisciplinary Research, College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China.
authors.forename: Wen-de
authors.initials: WD
authors.lastname: Tian
authors.affiliation: Department of Physics, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Pei-Qing
authors.initials: PQ
authors.lastname: Tong