Conformational evolution under steady shear flow: a comparison between cyclic and linear block copolymers

Chen, Quan

doi:10.1007/s00397-011-0596-4

Cited by 3 publications

(1 citation statement)

References 21 publications

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“…Namely, the low-frictional A segments become more highly oriented on average than the high-frictional B segments. This seemingly contradictory result was attributable to, as explained in our previous study (Chen 2011), that the high-frictional B segments of two end blocks, in particular those near the two junction points, tend to orient along the same direction and thus exhibit strong orientational correlation. These highly correlated B segments exert a tensile force (along their orientation) on the central A block, thereby increasing the segmental anisotropy of the A segments.…”

Section: Resultsmentioning

confidence: 77%

Creep dynamics of non-entangled miscible polymer blends and block copolymers

Chen

2012

Rheol Acta

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The bead-spring model, as a fundamental model of polymer physics, has been widely utilized so far for polymer chains under the strain-controlled conditions. Nevertheless, full analysis of conformational dynamics of the polymer chains during the creep (stress-controlled) process has not been given until recently by Watanabe and Inoue (Rheol. Acta 43: 634-644, 2004a). In this paper, this analysis is extended to disordered block copolymers and miscible polymer blends for which an effect of frictional distribution/heterogeneity manifests. Due to the requirement of constant stress, segments of different blocks of the block copolymers as well as those of different components of the polymer blends exhibit correlated anisotropic change during the creep process. Furthermore, this change contains two stages with a growth of the orientational correlation among the segments, that is, the first segmental stage where the anisotropic change reflects the intrinsic mobility of segments, and the second global stage where the anisotropy approaches the steady-state defined with respect to the specific position of a chain.

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Section: Resultsmentioning

confidence: 77%

Creep dynamics of non-entangled miscible polymer blends and block copolymers

Chen

2012

Rheol Acta

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Conformational and Dynamical Evolution of Block Copolymers in Shear Flow

et al. 2020

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Conformation and dynamical evolution of block copolymers in shear flow is an important topic in polymer physics that underscores the forming process of various materials. We explored deformation and dynamics of copolymers composed of rigid or flexible blocks in simple shear flow by employing multiparticle collision dynamics integrated with molecular dynamics simulations. We found that compared with the proportion between rigid and flexible blocks, the type of the central blocks plays more important role in the conformational and dynamical evolution of copolymers. That is, if the central block is a coil, the copolymer chain takes end-over-end tumbling motion, while if the central block is a rod, the copolymer chain undergoes U-shape or S-shape deformation at mid shear rate. As the shear strength increases, all copolymers behave similar to flexible polymers at high shear rate. This can be attributed to the fact that shear flow is strong enough to overcome the buckling force of the rigid blocks. These results provide a deeper understanding of the roles played by rod and coil blocks in copolymers for phase interface during forming processing.

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Theory of mobility of inhomogeneous-polymer-grafted particles

Tian

Chen

et al. 2023

The Journal of Chemical Physics

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We develop a theory for the motion of a particle grafted with inhomogeneous bead-spring Rouse chains via the generalized Langevin equation (GLE), where individual grafted polymers are allowed to take different bead friction coefficients, spring constants, and chain lengths. An exact solution of the memory kernel K(t) is obtained for the particle in the time (t) domain in the GLE, which depends only on the relaxation of the grafted chains. The t-dependent mean square displacement g(t) of the polymer-grafted particle is then derived as a function of the friction coefficient γ0 of the bare particle and K(t). Our theory offers a direct way to quantify the contributions of the grafted chain relaxation to the mobility of the particle in terms of K(t). This powerful feature enables us to clarify the effect on g(t) of dynamical coupling between the particle and grafted chains, leading to the identification of a relaxation time of fundamental importance in polymer-grafted particles, namely, the particle relaxation time. This timescale quantifies the competition between the contributions of the solvent and grafted chains to the friction of the grafted particle and separates g(t) into the particle- and chain-dominated regimes. The monomer relaxation time and the grafted chain relaxation time further divide the chain-dominated regime of g(t) into subdiffusive and diffusive regimes. Analysis of the asymptotic behaviors of K(t) and g(t) provides a clear physical picture of the mobility of the particle in different dynamical regimes, shedding light on the complex dynamics of polymer-grafted particles.

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Conformational evolution under steady shear flow: a comparison between cyclic and linear block copolymers

Cited by 3 publications

References 21 publications

Creep dynamics of non-entangled miscible polymer blends and block copolymers

Creep dynamics of non-entangled miscible polymer blends and block copolymers

Conformational and Dynamical Evolution of Block Copolymers in Shear Flow

Theory of mobility of inhomogeneous-polymer-grafted particles

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