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6. Constraint Release Mechanisms for H-Polymers Moving in Linear Matrices of Varying Molar Masses

Author

UCL - SST/IMCN - Institute of Condensed Matter and Nanosciences, Lentzakis, Helen, Costanzo, Salvatore, Vlassopoulos, Dimitris, Colby, Ralph H., Read, Daniel Jon, Lee, Hyojoon, Chang, Taihyun, van Ruymbeke, Evelyne, UCL - SST/IMCN - Institute of Condensed Matter and Nanosciences, Lentzakis, Helen, Costanzo, Salvatore, Vlassopoulos, Dimitris, Colby, Ralph H., Read, Daniel Jon, Lee, Hyojoon, Chang, Taihyun, and van Ruymbeke, Evelyne

Abstract

We investigate the influence of the environment on the relaxation dynamics of well-defined H-polymers diluted in a matrix of linear chains. The molar mass of the linear chain matrix is systematically varied and the relaxation dynamics of the H-polymer is probed by means of linear viscoelastic measurements, with the aim to understand its altered motion in different blends, compared to its pure melt state. Our results indicate that short unentangled linear chains accelerate the relaxation of both the branches and the backbone of the H-polymers by acting as an effective solvent. On the other hand, the relaxation of the H-polymer in an entangled matrix is slowed-down, with the degree of retardation depending on the entanglement number of the linear chains. We show that this retardation can be quantified by considering that the H-polymers are moving in a dilated tube at the rhythm of the motion of the linear matrix.

Published
2019

8. HPLC Characterization of Hydrogenous Polystyrene-block-deuterated polystyrene Utilizing the Isotope Effect

Author

Lee, Sanghoon, Lee, Hyojoon, Thieu, Lam, Jeong, Youncheol, Chang, Taihyun, Fu, Chao, Zhu, Yutian, and Wang, Yongmei

Abstract

HPLC elution behavior of isotopically different block copolymers was investigated. A series of three diblock copolymers of hydrogenous polystyrene and deuterated polystyrene (hPS-b-dPS), in which the length of hPS-block is fixed at 18 kg/mol and the length of dPS-block is varied from 17 kg/mol to 80 kg/mol, was synthesized and their retention behavior in liquid chromatography at critical condition (LCCC) was investigated using a C18 coated silica stationary phase and a mixed solvent of CH2Cl2and CH3CN. At this LC separation condition, hPS is retained slightly longer than dPS. The LCCC separations were performed at both LCCC conditions of dPS and hPS established with the same stationary and mobile phases, but at different column temperatures. Since the chromatographic retention difference between dPS and hPS is very small, it was possible to elute the block copolymers at both exclusion and interaction modes at the critical condition of each individual block. We found that the block at its critical condition is not fully “invisible” in both cases. In the LCCC separation at the critical condition of dPS, hPS-b-dPS elutes after the injection solvent peak (interaction mode) due to the stronger interaction of the hPS block. Although they have the same hPS block, they do not coelute but elute in the order of decreasing total molecular weight like an elution in exclusion mode. It clearly demonstrates that the dPS block is not “invisible” at the critical condition but influences the retention of the block copolymers. Monte Carlo simulations of the partition coefficient of A-b-B into a slit pore were performed to give insight on the elution behavior of A-b-B at the critical condition of the B block. The simulation shows that a block under the critical condition influences the retention of the other “visible” block whether the “visible” block is eluted in exclusion or interaction mode. When A is eluted in the interaction mode and B is at its critical condition, the partition coefficient is found to decrease with the increase of the “invisible” B block length, conforming to the observed elution behavior in experiments.

Published
2024
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9. Architectural Dispersity in Model Branched Polymers: Analysis andRheological Consequences

Author

UCL - SST/IMCN/BSMA - Bio and soft matter, Snijkers, Franck, Van Ruymbeke, Evelyne, Kim, Paul, Lee, Hyojoon, Nikopoulou, Anastasia, Chang, Taihyun, Hadjichristidis, Nilos, Pathak, Jai, Vlassopoulos, Dimitris, UCL - SST/IMCN/BSMA - Bio and soft matter, Snijkers, Franck, Van Ruymbeke, Evelyne, Kim, Paul, Lee, Hyojoon, Nikopoulou, Anastasia, Chang, Taihyun, Hadjichristidis, Nilos, Pathak, Jai, and Vlassopoulos, Dimitris

Abstract

We combine state-of-the-art synthetic, chromatographic, rheological, and modeling techniques in order to address the role of architectural polydispersity in the rheology of model branched polymers. This synergy is shown to be imperative in the field and leads to several important results. Even the best available synthesis is prone to “contamination” by side-products. The exact targeted macromolecular structure can be analyzed experimentally and statistically and eventually fractionated. Temperature-gradient interaction chromatography proves to be an indispensible tool in this process. All techniques are sensitive to the various macromolecular structures, but in different ways. In particular, the presence of side-products may or may not influence the linear rheology, due to competing contributions of the different relaxation processes involved, reflecting different structures at different fractions. Hence, combination of all these techniques is the key for fully decoding the architectural composition of branched polymers and its influence on rheology.

Published
2011

11. Viscosity of Ring Polymer Melts

Author

Pasquino, Rossana, primary, Vasilakopoulos, Thodoris C., additional, Jeong, Youn Cheol, additional, Lee, Hyojoon, additional, Rogers, Simon, additional, Sakellariou, George, additional, Allgaier, Jürgen, additional, Takano, Atsushi, additional, Brás, Ana R., additional, Chang, Taihyun, additional, Gooßen, Sebastian, additional, Pyckhout-Hintzen, Wim, additional, Wischnewski, Andreas, additional, Hadjichristidis, Nikos, additional, Richter, Dieter, additional, Rubinstein, Michael, additional, and Vlassopoulos, Dimitris, additional

Published
2013
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24. Characterization of BranchedPolymers by Comprehensive Two-Dimensional Liquid Chromatography withTriple Detection.

Author

Ahn, Seonyoung, Lee, Hyojoon, Lee, Sekyung, and Chang, Taihyun

Subjects
*POLYMERS, *LIQUID chromatography, *CHROMATOGRAPHIC analysis, *MOLECULAR weights, *TEMPERATURE effect, *SEPARATION (Technology)
Abstract

In the branching analysis by size exclusion chromatography(SEC)/triple detection (concentration, light scattering, and viscositydetectors) method, the branch number is calculated from the extentof chain size contraction due to chain branching relative to the linearpolymer of the same molecular weight (MW). A problem can arise fromthe fact that polymer chain size depends on both MW and chain branching.Since SEC separates polymers according to the chain size, an SEC fractionof randomly branched polymers may contain polymer species heterogeneousin both MW and chain architecture in general. As a solution of theproblem, we propose a separation of polymers by interaction chromatographyaccording to MW first and then measure the chain size distributionof polymers in the homogeneous MW fraction by SEC/triple detection.The analysis scheme is successfully established by online two-dimensionalliquid chromatography combining temperature gradient interaction chromatographyand SEC/triple detection. [ABSTRACT FROM AUTHOR]

Published
2012
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25. Constraint Release mechanisms for H-Polymers moving in Linear Matrices of varying molar masses

Author

Hyojoon Lee, Helen Lentzakis, Taihyun Chang, Salvatore Costanzo, Dimitris Vlassopoulos, Daniel J. Read, Evelyne Van Ruymbeke, Ralph H. Colby, Lentzakis, Helen, Costanzo, Salvatore, Vlassopoulos, Dimitri, Colby, Ralph H., Read, Daniel Jon, Lee, Hyojoon, Chang, Taihyun, van Ruymbeke, Evelyne, and UCL - SST/IMCN - Institute of Condensed Matter and Nanosciences

Subjects
chemistry.chemical_classification, Quantitative Biology::Biomolecules, Materials science, Molar mass, Polymers and Plastics, Dynamics (mechanics), Organic Chemistry, 02 engineering and technology, Polymer, Quantum entanglement, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Viscoelasticity, 0104 chemical sciences, Inorganic Chemistry, Condensed Matter::Soft Condensed Matter, Matrix (mathematics), chemistry, Chain (algebraic topology), Chemical physics, Materials Chemistry, Relaxation (approximation), 0210 nano-technology
Abstract

We investigate the influence of the environment on the relaxation dynamics of well-defined H-polymers diluted in a matrix of linear chains. The molar mass of the linear chain matrix is systematically varied and the relaxation dynamics of the H-polymer is probed by means of linear viscoelastic measurements, with the aim to understand its altered motion in different blends, compared to its pure melt state. Our results indicate that short unentangled linear chains accelerate the relaxation of both the branches and the backbone of the H-polymers by acting as an effective solvent. On the other hand, the relaxation of the H-polymer in an entangled matrix is slowed-down, with the degree of retardation depending on the entanglement number of the linear chains. We show that this retardation can be quantified by considering that the H-polymers are moving in a dilated tube at the rhythm of the motion of the linear matrix.

Published
2019

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