EUROPEAN POLYMER JOURNAL
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2024
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IF 5.8
Yangjing Chen,Zhiyu Hu,Hongting Pu
The incorporation of nanoparticles into linear polymers can significantly alter the rheological properties of the system. Nevertheless, the fundamental mechanisms behind this phenomenon have remained elusive. In present study, the changes in the microstructure, particularly the mesh size ( ξ ) and relaxation time ( τ d ) of entangled chains, in a fully polymer/single chain nanoparticles (SCNPs) nanocomposite (PNC) composed of linear polymethyl methacrylate (PMMA) chains and PMMA SCNPs was investigated by microrheological techniques. This research aims to elucidate the mechanism by which soft nanofillers affects the macroscopic properties of SCNP and linear polymer composite systems from a microstructural perspective. Results reveal that SCNPs demonstrate rapid chain segment relaxation and exhibit low viscosity in solution due to three-dimensional spherical structure. More importantly, the addition of SCNPs to the linear matrix significantly modifies the entanglement behavior of the linear polymer, decreasing the entanglement density (lager mesh size), resulting in a lower viscosity, and quicker relaxation times for the system. Additionally, it is observed that the dispersed nature and high penetrability of SCNPs lead to increased disorder in their conformation in solution as their size grows, which gradually diminishes their impact on the entanglement behavior of the system’s chains. Consequently, the effect of SCNPs on the rheological behavior of the system shows a strong dependence on size.
研究领域:
材料科学
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高分子物理
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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
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流变学
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产品关联
DOI
高影响因子
MACROMOLECULAR RAPID COMMUNICATIONS
·
2017
·Vol. 38
·期 17
·1700269
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IF 4.265
Hui Cao,Zhigang Cui,Pan Gao,Yi Ding,Xuechao Zhu,Xinhua Lu,Yuanli Cai
Easy access to discrete nanoclusters in metal-folded single-chain nanoparticles (metal-SCNPs) and independent ultrafine sudomains in the assemblies via coordination-driven self-assembly of hydrophilic copolymer containing 9% imidazole groups is reported herein. 1 H NMR, dynamic light scattering, and NMR diffusion-ordered spectroscopy results demonstrate self-assembly into metal-SCNPs (>70% imidazole-units folded) by neutralization in the presence of Cu(II) in water to pH 4.6. Further neutralization induces self-assembly of metal-SCNPs (pH 4.6–5.0) and shrinkage (pH 5.0–5.6), with concurrent restraining residual imidazole motifs and hydrophilic segment, which organized into constant nanoparticles over pH 5.6–7.5. Atomic force microscopy results evidence discrete 1.2 nm nanoclusters and sub-5-nm subdomains in metal-SCNP and assembled nanoparticle. Reduction of metal center using sodium ascorbate induces structural rearrangement to one order lower than the precursor. Enzyme mimic catalysis required media-tunable discrete ultrafine interiors in metal-SCNPs and assemblies have hence been achieved.
研究领域:
材料科学
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化学
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纳米医学
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产品关联
DOI
PubMed
高影响因子
MACROMOLECULAR RAPID COMMUNICATIONS
·
2024
·
IF 4.2
Yongming Zeng,Tianchi Xu,Weizhi Chen,Jianglin Fang,Dongzhong Chen
Organic and polymer fluorescent nanomaterials have been a frontier research focus. Here in this work, a series of fluorinated zwitterionic random copolymers end-attached with a quasi-chromophoric group of pyrene or tetraphenylethylene (TPE) have been well synthesized via atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP). Those random copolymers with total degree of polymerization 100 or 200 are able to produce fluorescent single-chain nanoparticles (SCNPs) through intra-chain self-folding assembly with quite uniform diameters in the range of 10∼20 nm as characterized by dynamic light scattering and transmission electron microscopy. By virtue of the segregation or confinement effect, both SCNPs functionalized with pyrene or TPE group are capable of emitting fluorescence, with pyrene tethered SCNPs exhibiting stronger fluorescence emission reaching the highest quantum yield around 20%. Moreover, such kind of fluorescent SCNPs manifest low cytotoxicity and good cell imaging performance for Hela cells. The creation of fluorescent SCNPs through covalently attached one quasi-chromophore to the end of one fluorinated zwitterionic random copolymer provides an alternative strategy for preparing polymeric luminescence nanomaterials, promisingly serving as a new type of fluorescent nanoprobes for biological imaging applications. This article is protected by copyright. All rights reserved
研究领域:
材料科学
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生物医学工程
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高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER
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2023
·
IF 4.6
Jiankang Liu,Zhijian Lv,Yini Fang,Guozhang Wu,Yu Lin
Polymer Single-chain nanoparticles (SCNPs) with different cross-linking densities were synthetized from poly (methyl methacrylate-co-(2-acetoacetoxy) ethyl methacrylate) (PMMA-co-PAEMA) random copolymers , and the molecular dynamics of SCNPs was investigated using differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The DSC results show that the glass transition temperature ( T g ) of SCNPs formed after intra-molecular cross-linking is higher than that of linear precursor, and increases with increasing the cross-linking density. The BDS results reveal that the segment ( α ) relaxation of SCNPs is significantly inhibited, as evidenced by an increase in the relaxation time and a decrease in the dielectric strength . This is due to the intra-molecular topological constraints which limits the mobility of the polymer segments. Moreover, the distribution width of α relaxation is broader, indicating a more pronounced dynamical heterogeneity . The relaxation time of Johari-Goldstein β ( β JG ) relaxation increases slightly, neither the dynamics nor the peak width of β JG relaxation is affected by intra-molecular cross-linking.
研究领域:
高分子化学
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材料科学
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产品关联
DOI
高影响因子
Polymer Chemistry
·
2017
·Vol. 8
·期 24
·3755-3763
·
IF 5.375
Zhigang Cui,Hui Cao,Yi Ding,Pan Gao,Xinhua Lu,Yuanli Cai
Herein, we present supramolecular compartmentalization of an ABC triblock copolymer single-chain nanoparticle (SCNP) using coordination-driven orthogonal intramolecular self-assembly in aqueous solution. A well-defined ABC-type triblock copolymer was synthesized via visible-light-mediated RAFT aqueous sequential block copolymerization. It possesses protonated imidazolium-motifs in the A-, NH3+-motifs in C-, and hydroxyl-motifs in B-block. Coordination-driven orthogonal self-assembly locally occurring upon deprotonation (A-block within pH 3.3–4.4 and C-block within pH 5.3–6.4) has been evidenced by UV-vis spectroscopy, 1H NMR, dynamic light scattering (DLS), NMR diffusion-ordered spectroscopy (DOSY), and atomic force microscopy (AFM). A blank regime of pH 4.4–5.3 guarantees locally orthogonal intramolecular self-assembly without mutual interference. Dialysis and pH-cycling results illustrate that the inherent different subdomains are discrete and can individually respond to an external stimulus, with potential biomimetic functions in terms of sub-10 nm ultrafine internal heterogeneity.
研究领域:
材料科学
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化学
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纳米技术
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生物材料
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产品关联
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 18
·2743-2751
·
IF 5.582
Wei Wen,Aihua Chen
Polymerization induced hierarchical self-assembly (PIHSA) has been developed as a facile and robust method to prepare non-spherical polymer nanoparticles at high solid content. But the current PIHSA formulations are limited to linear liquid crystalline (LC) block copolymers (BCPs). Besides, the non-spherical morphology library is desired to be enriched for more morphology-dependent applications. In this work, intramolecularly folded single chain nanoparticles (SCNPs) with steric character are used as stabilizers to construct reversible addition–fragmentation chain transfer (RAFT) dispersion PIHSA formulation for the first time. The study of the polymerization kinetics illustrates the controlled characteristic. The influence of SCNP stabilizers on the self-assembly behavior is investigated in detail by tuning the polymerization degree of core-forming blocks, solid contents, and intrachain cross-linking degree of the SCNPs. The results suggest that the morphology evolution is significantly affected by the architecture of the SCNP stabilizers. Under the synergistic effect of the steric architecture of the outside SCNP stabilizers and internal LC ordering, a unique morphology evolution of sphere–cuboid–holbrick–jujube, rather than typical sphere to one-dimensional morphology, was observed. This work provides a facile route to polymeric nanoparticles with unique non-spherical morphologies and demonstrates that introducing SCNP into polymerization induced self-assembly formulation is a promising approach for morphological control.
研究领域:
高分子化学
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纳米材料科学
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自组装
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功能高分子
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胶体与界面化学
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DOI
高影响因子
Polymer Chemistry
·
2024
·Vol. 15
·期 8
·733-741
·
IF 4.1
Yalan Sun,Zichao Deng,Aihua Chen
Polymer particles with inverse bicontinuous structures are widely used due to their well-defined ordered porous networks. These structures are typically prepared by the traditional self-assembly of amphiphilic block copolymers (BCPs) in solution or polymerization-induced self-assembly (PISA). In both methods, BCPs must be highly asymmetric with long hydrophobic chains. In this study, we report a credible approach where single-chain nanoparticles (SCNPs) preferentially self-assemble into inverse bicontinuous structures by folding the hydrophilic chains of BCPs, which can reduce the molecular area a0 and thus increase the packing parameter (P) to greater than unity. It is anticipated that this strategy will lessen the rigorous requirement of inverse bicontinuous structures on the BCP asymmetry. To illustrate this strategy, we prepared tadpole-like SCNPs of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) by intrachain cross-linking the P4VP blocks. Polymer cubosomes could be self-assembled from both linear BCPs and tadpole-like SCNPs, resulting in a distinct reduction in the minimal volume fractions of PS (fPS) (94.4% and 91.1%, respectively). A plausible formation mechanism for cubosomes was proposed. In addition, the efficiency of intrachain cross-linking and the property of the co-solvent played crucial roles in the formation of cubosomes. Overall, this work provides an effective method for preparing polymer particles with inverse bicontinuous structures from relatively low-asymmetric BCPs with a broad window.
研究领域:
高分子科学
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材料科学
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纳米技术
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软物质物理
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化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）