Melt Rheology of Short-Chain Branched Ring Polymers in Shear Flow

Jeong, Seung Heum; Ha, Tae Yong; Cho, Soowon; Roh, Eun; Kim, Jun Mo; Baig, Chunggi

doi:10.1021/acs.macromol.1c01727

Cited by 9 publications

(10 citation statements)

References 68 publications

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“…The alignments of the polymer chains in the shear direction induce the shear-thinning behavior of the polymer system. 48,49 The shear-thinning behavior has been commonly observed for other thermogelling systems, including poly(2methyl-2-oxazoline)-poly(2-propyl-2-oxazine) hydrogel, supramolecular branched DNA hydrogel, and multiblock copolymer hydrogel of polycaprolactone/PEG/polypropylene glycol incorporating cellulose nanofibers. 50−52 G′ and G″ were also studied in a frequency sweep mode after gelation.…”

Section: Resultsmentioning

confidence: 96%

Poly(l-threonine-co-l-threonine Succinate) Thermogels for Sustained Release of Lixisenatide

Park,

Piao,

Lee

et al. 2024

Biomacromolecules

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Negatively charged poly(L-Thr-co-L-Thr succinate) (PTTs) was developed as a new thermogel. Aqueous PTT solutions underwent thermogelation over a concentration range of 6.0−8.3 wt %. Dynamic light scattering, FTIR, 1 H NMR, and COSY spectra revealed the partial strengthening of the β-sheet conformation and the dehydration of PTTs during the transition. Extendin-4 was released from the PTTs thermogel with a large initial burst release, whereas positively charged lixisenatide significantly reduced its initial burst release to 25%, and up to 77% of the dose was released from the gel over 14 days. In vivo study revealed a high plasma concentration of lixisenatide over 5 days and hypoglycemic efficacy was observed for type II diabetic rats over 7−10 days. The biocompatible PTTs were degraded by subcutaneous enzymes. This study thus demonstrates an effective strategy for reducing the initial burst release of protein drugs from thermogels with the introduction of electrostatic interactions between the drug and the thermogel.

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Section: Resultsmentioning

confidence: 96%

Poly(l-threonine-co-l-threonine Succinate) Thermogels for Sustained Release of Lixisenatide

Park,

Piao,

Lee

et al. 2024

Biomacromolecules

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“…48−51 We additionally note that the results of the bulk region of the confined ring and SCB ring PE systems are in good agreement with those of the bulk ring and SCB ring PE systems. 85 In conjunction with ⟨R g 2 ⟩, bulk chains of the pure ring and SCB ring systems display a decreasing behavior in ⟨θ⟩ as they become more and more aligned to the flow (x-)direction with increasing flow strength (Figure 2b). However, the SCB ring chains are shown to be considerably less aligned than the pure ring systems due to the structural disturbance caused by the fast random motions of highly mobile short branches along the ring backbone.…”

Section: Resultsmentioning

confidence: 99%

“…Each system was subjected to a steady shear flow over a broad range of flow strengths (i.e., 1 ≤ Wi ≤ 5000), where the Weissenberg number Wi is defined as the product of the applied shear rate γ̇ and the longest characteristic relaxation time, τ R , of the system. τ R was estimated to be 9.8 ± 0.4 and 45 ± 2.2 ns for the corresponding bulk pure ring and SCB ring PE melts, respectively, based on the integral below the stretched-exponential decay of the time autocorrelation function of the unit ring diameter vector of polymer chains. , To obtain statistically accurate results, the simulations for pure ring and SCB ring systems were executed for a sufficiently long time (e.g., more than 3 times the longest relaxation time of the corresponding bulk system). Additional details of the potential model and simulation method are given in the Supporting Information.…”

Section: System Studied and Simulation Methodsmentioning

confidence: 99%

“…84 A recent NEMD study of bulk SCB ring melt systems under shear flow reported a distinctive synergistic influence of the closed-loop ring geometry and short-chain branching on the polymer structure and rheology in association with tight topological linking between SCB ring chains through enhanced interchain branch−branch and branch−backbone interactions. 85 The combined effects of ring topology and shortchain branching were further investigated in our recent NEMD simulations for the confined SCB ring polymer melts under shear flow. 86 The results of that study showed that the ring geometry and short branches synergistically increase the polymer−wall friction exerted on interfacial chains in the weak-to-intermediate flow regimes, leading to a significantly lower degree of interfacial slip for the SCB ring system than the corresponding pure ring and SCB linear systems.…”

Section: Introductionmentioning

confidence: 99%

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Interfacial Polymer Rheology of Entangled Short-Chain Branched Ring Melts in Shear Flow

Ha,

Jeong,

Baig

2024

Macromolecules

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We present a detailed analysis of the rheological behavior of entangled short-chain-branched (SCB) ring polymers at interfaces via direct comparison with the corresponding pure (unbranched) ring polymers using atomistic nonequilibrium molecular dynamics simulations of confined polyethylene melt systems under shear flow. To elucidate the general structural and dynamical characteristics of interfacial polymer chains, we analyze various physical properties of the chains in the bulk and interfacial regions separately within the confined systems, such as the chain radius of gyration and its distribution, the average streaming velocity profile, and the degree of interfacial slip, with respect to the applied flow strength. The pure ring polymer melt has a highly extended and aligned chain structure along the flow (x-)direction at the interface, even under weak flow fields, indicative of the strong wall effects via the attractive polymer−wall interactions. In contrast, the interfacial SCB ring chains generally form a compact structure like that of the corresponding bulk chains in the weak flow regime, representing a significant role of the short branches to effectively diminish the wall effect. In conjunction with these structural characteristics, the entangled SCB ring polymer melt displays a markedly smaller degree of interfacial slip than the corresponding pure ring analogue in the weak-to-intermediate flow regimes. Furthermore, while both the pure ring and the SCB ring polymer melt systems reveal similar fundamental molecular mechanisms at the interface with respect to the flow strength (i.e., z-to-x rotation, loop wagging, loop migration, and loop tumbling mechanisms), the SCB ring polymer melt displays relatively weaker loop migration and loop wagging dynamics with highly curvy backbone structures in the intermediate flow regime. In the strong flow regime, both the pure ring and SCB ring systems exhibit the loop tumbling mechanism together with intensive collisions between the interfacial chains and the wall. However, the interfacial SCB ring chains execute substantial loop migration dynamics even at high flow fields, which facilitates interfacial slip.

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“…The properties of the branched polymer in equilibrium and nonequilibrium conditions have been investigated by theoretical analysis [ 25 , 26 , 27 , 28 , 29 ], experiments [ 24 , 26 , 27 , 30 , 31 , 32 , 33 ] and simulations [ 9 , 34 , 35 , 36 , 37 , 38 , 39 ]. The influence of long-chain branching on the rheological properties of conventional polyolefins, such as polyethylene (PE) [ 40 , 41 , 42 , 43 , 44 ] and polypropylene (PP), has been investigated [ 45 , 46 , 47 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamical and Structural Properties of Comb Long-Chain Branched Polymer in Shear Flow

Wang

Wen

Zhang

et al. 2022

IJMS

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Using hybrid multi-particle collision dynamics (MPCD) and a molecular dynamics (MD) method, we investigate the effect of arms and shear flow on dynamical and structural properties of the comb long-chain branched (LCB) polymer with dense arms. Firstly, we analyze dynamical properties of the LCB polymer by tracking the temporal changes on the end-to-end distance of both backbones and arms as well as the orientations of the backbone in the flow-gradient plane. Simultaneously, the rotation and tumbling behaviors with stable frequencies are observed. In other words, the LCB polymer undergoes a process of periodic stretched–folded–stretched state transition and rotation, whose period is obtained by fitting temporal changes on the orientation to a periodic function. In addition, the impact induced by random and fast motions of arms and the backbone will descend as the shear rate increases. By analyzing the period of rotation behavior of LCB polymers, we find that arms have a function in keeping the LCB polymer’s motion stable. Meanwhile, we find that the rotation period of the LCB polymer is mainly determined by the conformational distribution and the non-shrinkable state of the structure along the velocity-gradient direction. Secondly, structural properties are numerically characterized by the average gyration tensor of the LCB polymer. The changes in gyration are in accordance with the LCB polymer rolling when varying the shear rate. By analyzing the alignment of the LCB polymer and comparing with its linear and star counterparts, we find that the LCB polymer with very long arms, like the corresponding linear chain, has a high speed to reach its configuration expansion limit in the flow direction. However, the comb polymer with shorter arms has stronger resistance on configuration expansion against the imposed flow field. Moreover, with increasing arm length, the comb polymer in shear flow follows change from linear-polymer-like to capsule-like behavior.

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Melt Rheology of Short-Chain Branched Ring Polymers in Shear Flow

Cited by 9 publications

References 68 publications

Poly(l-threonine-co-l-threonine Succinate) Thermogels for Sustained Release of Lixisenatide

Poly(l-threonine-co-l-threonine Succinate) Thermogels for Sustained Release of Lixisenatide

Interfacial Polymer Rheology of Entangled Short-Chain Branched Ring Melts in Shear Flow

Dynamical and Structural Properties of Comb Long-Chain Branched Polymer in Shear Flow

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