MACROMOLECULES
·
2025
·
IF 5.2
Yifu Ruan,Hao Zhang,Qingzhi Zou,Pengfei Zhang,Rui Zhang,GengXin Liu
Polymer entanglements confer exceptional properties, but, at certain conditions, pose significant processing challenges. Disentangled polymers are thermodynamically unstable, leading to ambiguities in their dynamics. The soft nanoparticles (SNPs) may be considered a random coil stabilized by intramacromolecular cross-linking. As a model system of inhibited interpenetration, it could be used to illustrate the disentanglement and shed light on the boundary between polymers and colloids. We bring fractionation to SNPs and systematically curated over forty samples. Terminal relaxation time τ spanning nine decades was quantified while molecular mass spanning as narrow as two decades. Based on the analysis, governing equations for τ were established as functions of bulk diameter (Dbulk) and cross-linking strand length (Nc). We identify the parameter space capable of reducing τ 1000 times, defining the limits of disentanglement. Compared to linear polymers of equivalent molecular weights, lightly cross-linked polymeric nanoparticles exhibit significantly faster relaxation and improved processability. At larger Dbulk and Nc, τ shows a greater divergence than the mechanism of entanglements. Such precise fractionated SNPs are essential for achieving these quantitative insights.
研究领域:
高分子科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Yifu Ruan,Qingzhi Zou,Haoyan Zhang,Yipeng Zhang,Hao Zhang,Weiwei Wu,Hao Liu,Jiajun Yan,GengXin Liu
The melt rheology of single-chain nanoparticles (SCNPs), which are synthesized by intrachain cross-linking of linear precursors, remains an unresolved issue. In this study, we synthesized linear precursors with different molecular weights (MW) and varying mole percentages of cross-linkers (CrF). The cross-linker, 4-vinylbenzocyclobutene, undergoes thermal-induced coupling. The resulting SCNPs in the melt state exhibited four distinct types of linear viscoelastic behavior: 1) reduced entanglement, 2) viscous-dominant liquids, 3) viscoelastic liquid with an elastic plateau and terminal relaxation, and 4) viscoelastic solid, a persistent elastic plateau with unmeasurable long terminal relaxation times. We observed a nonmonotonic change in viscoelastic behavior as the cross-linking increases. At CrF equal to 4%, Type 1 SCNP is still polymer-like, but the degree of entanglement is reduced. When CrF increased to 8%, the elastic plateau completely disappeared, and the viscous-dominant behavior is similar to the Zimm or Rouse model. Complete disentanglement is achieved even for high MW. In Type 2, the relaxation times and zero-shear viscosities show weaker dependence (a power of 1) on MW compared to linear polymers (a power of 3.4). Thus, the relaxation times and viscosities of such SCNPs can be 100 times smaller than their linear counterparts of the same MW. At even higher CrF, the storage modulus would surpass the loss modulus again if the MW is sufficiently high. This elasticity is due to a mechanism other than entanglements but is analogous to the colloidal domain. Relaxation times or viscosities increase divergently and exceed the experimental measurability in Type 4. The boundary between Types 3 and 4 might be considered as the boundary between polymers and colloids. Using SCNPs as a model system for detailed rheological characterization, we demonstrate the dynamics of the transition from linear polymers to particles. Type 2 SCNPs could be regarded as the extreme of disentanglement, achieved by an appropriate amount of intrachain cross-linking. Such a significant viscosity reduction might support the development of more energy-efficient polymers.
研究领域:
材料科学
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高分子化学
·
流变学
✓ 已验证
产品关联
DOI
高影响因子
Soft Matter
·
2021
·Vol. 17
·期 48
·10829-10838
·
IF 3.679
Xiaohui Wang,Feifei Yan,Xue Bai,Hanchuan Li,Ming Yuan,Yanping Liu,Benjamin S. Hsiao,Chuntai Liu,Zhen Wang
Lamellar crystal-dominated (LCD) surfaces hold great superiority and broad prospects in polymer surface engineering. The key to this is avoiding the formation of an amorphous phase in the interlamellar region. Here we give a first report of achieving LCD surfaces of polyethylene films via melt stretching-induced free surface crystallization. We demonstrate that the resultant surface is constructed directly by orientated and edge-on lamellae within a surface depth of tens to hundreds of nanometers, while the normally existing amorphous phase is avoided. The crystallization-driven formation of the LCD surface has been ascribed to the heterogeneous chain dynamics of a melt free surface, that is, high chain mobility, low viscosity and loose chain entanglement, which facilitates the complete chain disentanglement during crystallization. In addition, we confirm that the surface morphology is controllable with respect to lamellar orientation, spacing and depth by changing the melt stretching strain or quenching the deformed melt. Meanwhile, owing to a possible kinetics competition between crystallization and chain disentanglement, the structural spacing of surface lamellae holds a positive correlation with the lamellar depth. Since free surface effects are immanent in polymer materials, the currently proposed melt processing strategy is demonstrated to be transferable to other semicrystalline polymers.
研究领域:
高分子材料科学
·
表面工程
✓ 已验证
DOI
高影响因子
POLYMER
·
2023
·
IF 4.6
WenKai Cao,BinXiao Wei,YinChuan Pu,LiPeng Wang,SiQi Su,YongPing Bai
Ethylene propylene diene monomer (EPDM) is difficult to demonstrate its excellent performance in the coatings due to its high entanglement between molecular chains. Inspired by the phase inversion of emulsions, the EPDM/PBMA organic dispersion was prepared through the penetration and in-situ polymerization of BMA . In this strategy, the increased solubility parameter of PBMA after polymerization led to the transition of EPDM from the continuous phase to the dispersed phase, and the disentangled chain of EPDM shrank back to the shape of rod or ball. The shape of the dispersed phase was related to the interfacial tension. Particularly, the main chains of PBMA were arranged at the interface rather than buried in EPDM to maintain the stability of the organic dispersion. The EPDM/PBMA organic dispersion had excellent elasticity, bending, dispersion stability, insulation, adhesion to the glass, and aging resistance. This study indicated that the EPDM/PBMA organic dispersion could be applied as the promising protective coating for flexible electronic devices.
研究领域:
材料科学
·
高分子化学
·
表面与界面科学
✓ 已验证
产品关联
DOI
高影响因子
ADVANCED MATERIALS
·
2025
·
IF 26.8
Huan Xia,Tao Shui,Xiaotian Wan,Yixi Chen,Fengyi Wang,Chunyang Miao,Xin Cao,Bingyige Pan,Zihe Pan,Qian Xie,Ye Chen,Wei Zhang,ZhengMing Sun
Flexible aqueous zinc-ion batteries (ZIBs) are promising candidates for next-generation wearable electronics and soft robotics, yet their development is hindered by the non-selective ion transport of conventional hydrogel electrolytes, which induces concentration polarization, uneven Zn 2+ flux, and dendrite formation, ultimately causing battery failure. Here, a microphase-separated single-zinc-ion conducting hydrogel electrolyte (SIHE) constructed via polymer chain disentanglement within a polyanionic zinc-alginate (ZA) matrix is reported. Due to the pronounced steric disparity between Zn 2+ and the alginate chains, ZA holds intrinsic potential for ion-selective transport. However, spontaneous chain entanglement within the alginate network under the applied electric field severely impedes the formation of continuous ion transport pathways, limiting Zn 2+ conduction. By incorporating Nafion, well-defined hydrophilic/hydrophobic domains are induced that simultaneously relax the entangled polymer network and establish continuous Zn 2+ -conducting pathways. This microstructural engineering enables a high Zn 2+ transference number of 0.967 and ionic conductivity of 25.5 mS cm −1 , resolving the long-standing trade-off between ion selectivity and transport kinetics. The zinc-alginate/Nafion (ZA/N) electrolyte enables dendrite-free cycling for over 4600 h. The ZA/N-based flexible ZIB retains 90% capacity after 5000 cycles at 10 A g −1 . This work presents a general strategy to engineer high-performance SIHEs for safe and durable flexible zinc-ion batteries.
研究领域:
储能
·
材料科学
·
电化学
·
柔性电子学
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电池技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）