The effect of polymer particle size on three-dimensional percolation in core-shell networks of PMMA/MWCNTs nanocomposites: Properties and mathematical percolation model

2018 ◽  
Vol 165 ◽  
pp. 1-8 ◽  
Author(s):  
Seung Han Ryu ◽  
Hong-Baek Cho ◽  
Seil Kim ◽  
Young-Tae Kwon ◽  
Jimin Lee ◽  
...  
Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1958
Author(s):  
Jae-Jung Park ◽  
Yongsoo Kim ◽  
Chanmin Lee ◽  
Donghyun Kim ◽  
Wonjun Choi ◽  
...  

Emulsion polymerization presents the disadvantage that the physical properties of polymer particles are altered by surfactant adsorption. Therefore, in the soap-free emulsion polymerization method, a hydrophilic initiator is utilized while inducing repulsion among particles on the polymer particle surface, resulting in stable polymer particle production. In this study, we developed a methodology wherein spherical and uniform poly(styrene-co-maleic anhydride) (PSMA)/polyethyleneimine (PEI) core–shell nanoparticles were prepared. Further, their morphology was analyzed. During PSMA polymerization, the addition of up to 30% maleic anhydride (MA) resulted in stable polymerization. In PSMA/PEI nanoparticle fabrication, the number of reactants increased with increased initial monomer feed amounts; consequently, the particle size increased, and as the complete monomer consumption time increased, the particle distribution widened. The styrene (St) copolymer acted as a stabilizer, reducing particle size and narrowing particle distribution. Furthermore, the monomers were more rapidly consumed at high initiator concentrations, irrespective of the initiator used, resulting in increased particle stability and narrowed particle distribution. The shell thickness and particle size were PEI feed ratio dependent, with 0.08 being the optimal PEI-to-MA ratio. The fabricated nanoparticles possess immense potential for application in environmental science and in chemical and health care industries.


Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1618
Author(s):  
Xin-Hui Pang ◽  
Yang Yang ◽  
Xin Bian ◽  
Bing Wang ◽  
Li-Kun Ren ◽  
...  

In order to make HPI have a wide application prospect in the food industry, we used EGCG to modify HPI. In this study, we prepared different concentrations (1, 2, 3, 4, and 5 mM) of (−)-epigallocatechin gallate (EGCG) covalently linked to HPI and use methods such as particle size analysis, circular dichroism (CD), and three-dimensional fluorescence spectroscopy to study the changes in the structure and functional properties of HPI after being covalently combined with EGCG. The particle size data indicated that the covalent HPI-EGCG complex was larger than native HPI, and the particle size was mainly distributed at about 200 μm. CD and three-dimensional fluorescence spectroscopy analyses showed that the conformation of the protein was changed by conjugation with EGCG. The β-sheet content decreased from 82.79% to 66.67% after EGCG bound to the protein, and the hydrophobic groups inside the protein were exposed, which increased the hydrophobicity of the protein and changed its conformation. After HPI and 1 mM of EGCG were covalently bonded, the solubility and emulsifying properties of the covalent complex were improved compared with native HPI. These results indicated that HPI-EGCG conjugates can be added in some foods.


2020 ◽  
Vol 4 (3) ◽  
Author(s):  
C. Kons ◽  
Manh-Huong Phan ◽  
Hariharan Srikanth ◽  
D. A. Arena ◽  
Zohreh Nemati ◽  
...  

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 730
Author(s):  
Erik Sarnello ◽  
Tao Li

Enzyme immobilization techniques are widely researched due to their wide range of applications. Polymer–protein core–shell nanoparticles (CSNPs) have emerged as a promising technique for enzyme/protein immobilization via a self-assembly process. Based on the desired application, different sizes and distribution of the polymer–protein CSNPs may be required. This work systematically studies the assembly process of poly(4-vinyl pyridine) and bovine serum albumin CSNPs. Average particle size was controlled by varying the concentrations of each reagent. Particle size and size distributions were monitored by dynamic light scattering, ultra-small-angle X-ray scattering, small-angle X-ray scattering and transmission electron microscopy. Results showed a wide range of CSNPs could be assembled ranging from an average radius as small as 52.3 nm, to particles above 1 µm by adjusting reagent concentrations. In situ X-ray scattering techniques monitored particle assembly as a function of time showing the initial particle growth followed by a decrease in particle size as they reach equilibrium. The results outline a general strategy that can be applied to other CSNP systems to better control particle size and distribution for various applications.


Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1201
Author(s):  
Xinghua Ji ◽  
Cheng Zhang ◽  
Shufeng Li

SiCp reinforced aluminium matrix composites (AMCs), which are widely used in the aerospace, automotive, and electronic packaging fields along with others, are usually prepared by ex situ techniques. However, interfacial contamination and poor wettability of the ex situ techniques make further improvement in their comprehensive performance difficult. In this paper, SiCp reinforced AMCs with theoretical volume fractions of 15, 20, and 30% are prepared by powder metallurgy and in situ reaction via an Al-Si-C system. Moreover, a combined method of external addition and an in situ method is used to investigate the synergistic effect of ex situ and in situ SiCp on AMCs. SiC particles can be formed by an indirect reaction: 4Al + 3C → Al4C3 and Al4C3 + 3Si → 3SiC + 4Al. This reaction is mainly through the diffusion of Si, in which Si diffuses around Al4C3 and then reacts with Al4C3 to form SiCp. The in situ SiC particles have a smooth boundary, and the particle size is approximately 1–3 μm. A core-shell structure having good bonding with an aluminium matrix was generated, which consists of an ex situ SiC core and an in situ SiC shell with a thickness of 1–5 μm. The yield strength and ultimate tensile strength of in situ SiCp reinforced AMCs can be significantly increased with a constant ductility by adding 5% ex situ SiCp for Al-28Si-7C. The graphite particle size has a significant effect on the properties of the alloy. A criterion to determine whether Al4C3 is a complete reaction is achieved, and the forming mechanism of the core-shell structure is analysed.


Nanoscale ◽  
2013 ◽  
Vol 5 (17) ◽  
pp. 7906 ◽  
Author(s):  
Qin-qin Xiong ◽  
Jiang-ping Tu ◽  
Xin-hui Xia ◽  
Xu-yang Zhao ◽  
Chang-dong Gu ◽  
...  

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