JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2020
·
IF 7.489
Hui Xue,Ziqing Zhao,Rui Chen,John L. Brash,Hong Chen
Hypothesis : Poly( N -isopropylacrylamide) microgels are used extensively in the design of drug carriers, surfaces for control of cell adhesion, and optical devices . Particle size is a key factor and has a significant influence in many areas. Experiments : In this work, precise control of the particle size of poly( N -isopropylacrylamide) microgels was achieved by controlling the separation distance of the poly( N -isopropylacrylamide) chains. Dibromoalkanes of different size were used as an adjustable “molecular ruler” to measure molecular dimensions in poly( N -isopropylacrylamide) nanoaggregates at the critical crosslinking temperature. Findings : We find that the chain separation distance decreases as the temperature increases with a sharp decrease over the 55-to-65 °C interval. Based on the observed relationships between chain separation and crosslinker, the particle size of poly( N -isopropylacrylamide) microgels can be regulated by changing the length of the “molecular ruler” (crosslinker) at the same temperature. Furthermore, for partly crosslinked poly( N -isopropylacrylamide) microgels that contain free crosslinkable sites, the particle size can be reduced still more by further crosslinking (“re-crosslinking”) with crosslinkers of different size. It is shown that the particle size can be regulated by adjusting the length of “molecular ruler” and the degree of crosslinking. This work provides a “molecular level” method for precise control of poly( N -isopropylacrylamide) microgel particle size.
研究领域:
材料科学
·
生物医学工程
·
纳米技术
✓ 已验证
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Zhihang Xu,Jian Du,Peng Shan,Yilin Wang,Leping Li,Yehan Tao,Jinwen Hu,Chenglong Fu,Yanna Lv,Zhenglei Jia,Xunyu Song,Haisong Wang
Polysaccharide-based active packaging materials have extensively explored in the field of food safety, whereas the highly hydrophilic traditional biopolymer was susceptible to be broken under moisture conditions, leading to the invalid food preservation. Herein, a multi-mechanism cross-linking densification strategy was employed to design and construct novel carboxymethyl chitosan (CMCS)/sodium alginate-dopamine complex (SD)/oxidized starch (OS)/tea polyphenol (TP) composite film (COSDT) composite. Multiple cross-linking reduces the spacing between polysaccharide chains to make the structure denser, hindering the adsorption and penetration of water molecules. The optimized COSDT-2 film maintains intact structures without any dissolution after immersing in water for 24 h and demonstrated relatively stable water contact angle of 71.97° at 1 s and 68.48° after 60 s. The water vapor permeability and oxygen transmission rate were reduced from 5.10 × 10 −7 g m −1 s −1 Pa −1 and 8.28 cm 3 μm (m 2 day KPa) −1 for COT sample to 1.03 × 10 −7 g·m −1 ·s −1 ·Pa −1 and 2.70 cm 3 μm (m 2 day KPa) −1 for COSDT-2 film. Moreover, COSDT films exhibited stable wet mechanical properties in high-humidity environments (95 % RH) of 30.76 MPa. COSDT-2 accelerated the release of tea polyphenols by structural loosening due to enhanced interchain repulsion under alkaline conditions, resulting in a significant reduction of volatile alkaline nitrogen production by 61.58 % in chicken breast meat and prolonged shelf life. This study provided a novel perspective in designing and constructing water-resistant active food packaging biofilms through modulating the interchain spacing of polymers.
研究领域:
食品科学
·
生物材料
·
包装工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Shaohui Xiong,Xingyi Ou,Qingquan Liu,Yiwen Li,Juntao Tang,Guipeng Yu,Chunyue Pan,Shibo Guo,Sitong Li,Menghan Yong
Polymers of intrinsic microporosity (PIM) have attracted considerable attention in the development of mixed matrix membranes (MMMs) for CO 2 separation. A prominent challenge lies in engineering the spacing of the polymer matrix chains while eliminating non-selective interfacial defects. In this study, a CO 2 -philic triazine-based porous polymer, featuring robust hydrogen bond donating groups, was employed to fabricate a series of interfacial defect-free PIM-1 based MMMs (denoted as PIM-1/CSU-1). The interfacial adhesion and compatibility have been greatly improved due to the strengthened hydrogen bond interaction, which was systematically validated through variable-temperature infrared spectroscopy. Additionally, the formation of hydrogen bonds allowed for the regulation of the polymer matrix chain spacing, making the chain distance loose. Remarkably, the resulting membrane exhibited a CO 2 permeability of 13,429 Barrer and CO 2 /N 2 selectivity of 33.1—246.6% and 70.2% higher than pristine PIM-1, respectively, surpassing the latest Jansen/McKeown upper bound established in 2019, but also significantly exceed the performance of previously reported MMMs for CO 2 separation. The strategy of mitigating interfacial defects through the formation of hydrogen bonds between fillers and the polymer matrix emerges as a viable and effective method for fabricating gas separation membranes with exceptional separation capabilities.
研究领域:
材料科学
·
高分子化学
·
气体分离
·
膜技术
·
物理化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2025
·
IF 9
Hanchao Gao,Linkang Gu,Shuxia Duan,Zhaopeng Xia,Kai Zhang,Wenxiu Yang,Chenwei Li,Xinyu Zhang,Yong Liu
Rational design molecular-level crosslinked structures of electret membranes remain a significant challenge for stable electrostatic filtration of airborne particles. Here, rigidity-tailored crosslinked networks, designed by modulating the molecular rigidity of interchain covalent bonds in crosslinked poly(styrene-co-maleic anhydride) (CS-IDDA), are exploited to function as deep traps to immobilize charges in electret membranes. The trapping sites capture charge carrier injected by corona discharging, obtaining deep-trapped electret CS-IDDA membranes. The electret CS-IDDA membranes maintain 99.83 % filtration efficiency after prolonged exposure to 95 % relative humidity environment. The remarkable filtration efficiency stability is attributed to deep-trapped charges with high energy level and improved charge retention enabled by restricted segmental mobility. Noteworthily, deep-trapped charges are anchored by connectivity defects and spatial inhomogeneity within rigid crosslinked networks. Moreover, the rigid crosslinked networks confine molecular chain movement by reducing interchain spacing and free volume, effectively suppressing charge migration, and hence dominate stable electrostatic capture of airborne particles. This study highlights the significance of modulating the molecular-scale rigidity engineering of crosslinked networks to effectively design electret membranes for advance air purification and safeguarding public health security.
研究领域:
材料科学
·
高分子化学
·
环境工程
·
静电学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2023
·Vol. 34
·期 10
·3125-3136
·
IF 3.4
Longwei Shi,Zheng Zhao,Lishuai Zong,Jinyan Wang,Xigao Jian
Limiting molecules' polarized motion effectively reduces the dielectric loss of materials. This article synthesized side chains with different lengths using p-ethoxyphenol, p-hydroxybenzoic acid, and long-chain halohydrins through a two-step process. These chains' movement was almost unaffected by the main chain of polymers, so they can fill up the free volume of polymers under certain conditions. 1,2-dihydro-4-(4-hydroxyphenyl)phthalazine-1-(2H)-one(DHPZ), 4,4'-Difluorophenyl sulfone(DFS), and 4,4-Bis(4-hydroxyphenyl) valeric acid(HPV) obtained three polymers with different carboxyl groups (10%, 30%, and 50%) through nucleophilic substitution. They were then grafted and treated with hot-pressing. The introduction of side chains could reduce the free volume of polymers under hot-pressing conditions, so further reducing the dielectric loss of materials. Polymer with the shortest and least (10%) side chains showed the most obvious dielectric loss tangent, the reduction rate of the film's dielectric loss tangent was 13.11% (at T g + 15°C, while the non-grafted one was only 3.69%) and 20.70% (at T g + 80°C, while the non-grafted one was only 8.35%), respectively. In addition, WXRD and DMA tests showed that films' intermolecular chain spacing (“ d ”) and T g changed after the hot-pressing process, respectively. The change law of both was consistent with that of dielectric loss tangent. Confirm that grafting high-motility side chains can significantly reduce polymer's dielectric loss by enhancing the free volume reduction effect after hot-pressing.
研究领域:
材料科学
·
高分子化学
·
电气工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）