Glass Transition of Disentangled and Entangled Polymer Melts: Single-Chain-Nanoparticles Approach

Singh, Manjesh Kumar; Hu, Minghan; Cang, Yu; Hsu, Hsiao‐Ping; Thérien-Aubin, Héloı̈se; Koynov, Kaloian; Fytas, George; Landfester, Katharina; Kremer, Kurt

doi:10.1021/acs.macromol.0c00550

Cited by 30 publications

(19 citation statements)

References 67 publications

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“…Singh et al. [ 114 ] even suggested that local packing dominates the glass transition process and that topological constraints due to chain entanglements do not play a significant role. More evidence is needed to further examine the impact of entanglement on T g .…”

Section: Effect Of Entanglement On the Polymer Propertiesmentioning

confidence: 99%

Control of Polymer Properties by Entanglement: A Review

Kong

Yang

Zhang

et al. 2021

Macro Materials & Eng

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Chain entanglement, either cohesional or topological, distinguishes polymers from other engineering materials. It impedes the movement of molecular segments and influences the polymer rheology, morphology, and mechanical properties. Although a high level of entanglement can increase the polymer toughness, excessive entanglement should be avoided because it causes a high melt viscosity making the processing difficult. This review tended to elucidate the influence of entanglement on the polymer structure, determining the material properties and processability. A wide range of methods used to fine control the degrees of chain entanglement are summarized. The methods are applicable to polymers in solutions, melts, and condensed states with advantages and limitations discussed in detail. The authors also examined the effect of the entanglement on polymer crystallization—the mechanism remains a controversial issue. This review will provide general guidance to designing and processing polymer materials with desired properties via a rational route of controlling the chain entanglement.

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Section: Effect Of Entanglement On the Polymer Propertiesmentioning

confidence: 99%

Control of Polymer Properties by Entanglement: A Review

Kong

Yang

Zhang

et al. 2021

Macro Materials & Eng

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“…The topological and/or architectural differences can have a large impact on the molecular behavior. Different chemical and physical properties, such as density [ 8 ], hydrodynamic size [ 8 , 9 , 10 , 11 , 12 ], viscosity [ 13 , 14 , 15 , 16 , 17 ], glass transition temperature [ 18 ], strength [ 19 ], and the dynamics [ 20 ], are affected by chain topology and/or architecture [ 21 , 22 ]. Scattering techniques present a great opportunity to study the intra-molecular cross-linking effects on SCNPs systems at a molecular level.…”

Section: Introductionmentioning

confidence: 99%

Collective Motions and Mechanical Response of a Bulk of Single-Chain Nano-Particles Synthesized by Click-Chemistry

et al. 2020

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We investigate the effect of intra-molecular cross-links on the properties of polymer bulks. To do this, we apply a combination of thermal, rheological, diffraction, and neutron spin echo experiments covering the inter-molecular as well as the intermediate length scales to melts of single-chain nano-particles (SCNPs) obtained through ‘click’ chemistry. The comparison with the results obtained in a bulk of the corresponding linear precursor chains (prior to intra-molecular reaction) and in a bulk of SCNPs obtained through azide photodecomposition process shows that internal cross-links do not influence the average inter-molecular distances in the melt, but have a profound impact at intermediate length scales. This manifests in the structure, through the emergence of heterogeneities at nanometric scale, and also in the dynamics, leading to a more complex relaxation behavior including processes that allow relaxation of the internal domains. The influence of the nature of the internal bonds is reflected in the structural relaxation that is slowed down if bulky cross-linking agents are used. We also found that any residual amount of cross-links is critical for the rheological behavior, which can vary from an almost entanglement-free polymer bulk to a gel. The presence of such inter-molecular cross-links additionally hinders the decay of density fluctuations at intermediate length scales.

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“…This may be due to the alternating distribution of amorphous regions between the lamellae. The melt stretching process leads to an increase in chain entanglement and an increase in the orientation of the carbon chain skeleton 50 . The highly oriented entangled molecular chains are confined between the lamellae, resulting in higher glass transition temperature.…”

Section: Resultsmentioning

confidence: 99%

The effect of melt drawing ratio on the crystal structural change and performance of polyketone extrusion cast film

Yin

Chen

et al. 2022

Journal of Polymer Science

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In this paper, the polyketone (POK) extrusion cast film is manufactured by melt stretching method, and the evolution process of the crystal morphology and mechanical properties with the increase of melt drawing ratio (MDR) are followed. The results show that the melt stretching process produces many micro shish-kebab crystals in the POK. The length of the shish crystal and the thickness of the kebab crystal hardly increase with MDR, but the lateral length of the kebab crystal shows linear growth when MDR exceeds 40. The crystalline morphology of POK is mainly affected by melt relaxation. The molecular chain has sufficient relaxation during cooling at a low MDR (20-40). At this time, micro shish-kebab crystals are mainly randomly arranged. When MDR exceeds 40, the rapid melt stretching shortens the relaxation time of the tie chain between the neighborhood shish crystal, and the atomic force microscopy image shows a typical shish-kebab structure. This experimental result indicates that the formation of the oriented lamella structure may be related to the relaxation of the molecular chains between the micro-shish. When the length of the shish axis and the thickness of the kebab lamellae are similar, it is difficult to distinguish the two.

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Glass Transition of Disentangled and Entangled Polymer Melts: Single-Chain-Nanoparticles Approach

Cited by 30 publications

References 67 publications

Control of Polymer Properties by Entanglement: A Review

Control of Polymer Properties by Entanglement: A Review

Collective Motions and Mechanical Response of a Bulk of Single-Chain Nano-Particles Synthesized by Click-Chemistry

The effect of melt drawing ratio on the crystal structural change and performance of polyketone extrusion cast film

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