REACTIVE & FUNCTIONAL POLYMERS
·
2019
·
IF 3.074
Wenqin Lai,Guozhang Wu
In this study the effect of flexible 1,4-cyclohexanedimethanol (CHDM) units on the reactive blending of poly(isosorbide- co -CHDM carbonate) (I c C-PC) with bisphenol-A polycarbonate (BPA-PC) was investigated and the contributions of chain flexibility and compatibility to transesterification were clarified. FTIR analysis revealed the presence of specific interactions between the CHDM segments of I c C-PC and the carbonyl group and phenyl rings of BPA-PC, leading to thermodynamic miscibility of the polymer blends when the CHDM content was higher than 50 mol% in I c C-PC. Addition of organotin catalysts during melt blending triggered transesterification between I c C-PC and BPA-PC, transforming the opaque blends into transparent alloys with a single T g when the transesterification ratio reached a critical value. It was found that the reactivity of isosorbide (ISB) segments was higher than that of CHDM segments. The increase in the CHDM/ISB ratio first accelerated and then slowed down the transesterification, demonstrating that, despite of the low reactivity of the CHDM segments, the enhanced chain flexibility and compatibility were effective for promoting transesterification. Anyway, copolymerization of CHDM with ISB improved the compatibility of I c C-PC with BPA-PC, reduced the critical transesterification ratio for transparency, and remarkably shortened the blending time essential for the large-scale fabrication of transparent ISB-based polycarbonate alloys by twin-screw reactive extrusion .
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2025
·
IF 2.8
Yumeng Zhang,Na Li,Yulong Xiao,Qiwen Yong,Yuechuan Wang,Yao Xiao,Jingxin Lei
The balance of chain flexibility and rigidity may improve the fluorescence quantum yields (QYs) of unconventional aggregation-induced emission (AIE) polymers. Herein, we prepared four crosslinked polyacrylic acids (CPAAs) with AIE effect using N,N′ -methylene bisacrylamide (MBA) as the crosslinker. The chain flexibility of the CPAAs decreases with the increase of MBA contents. These CPAAs show bright blue fluorescence under the irradiation of UV light. The maximum excitation wavelengths of the CPAAs are not near their UV absorption peaks because their emission is originated from the clustering of the oxygen atoms of the carbonyl groups, but not the ( n , π *) transition of the oxygen atoms. The emission spectra and fluorescent lifetime data both validate that all the CPAAs have similar emission species. Density functional theory calculations suggest the emission of the CPAAs comes from the carboxyl groups. One of the CPAAs with balanced chain flexibility and rigidity has an optimized fluorescence QY of 17.7%, which is much higher than that of the reported linear PAA of 4.5%.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2016
·
IF 2.567
Zhuo Chen,Zhuoyu Liu,Gebin Shen,Ruiheng Wen,Jie Lv,Jizhen Huo,Yingfeng Yu
Cycloaliphatic epoxy resin (3–4-epoxycyclohexane) methyl 3–4-epoxycyclohexyl-carboxylate (ECC) was formulated with flexible hydrogenated bisphenol A diglycidyl ether (HBADGE) to inspect the influence of chain flexibility on the performance and reliability of epoxy packaged Light-emitting Diode (LED). The properties of epoxy encapsulants were characterized by using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), ultraviolet visible (UV–vis) spectrophotometer, thermomechanical analyzer (TMA), scanning acoustic microscopy (SAM), and scanning electron microscopy (SEM). With the incorporation of flexible HBADGE, favorable properties were obtained, such as decreased thermal expansion coefficient (CTE), lowered storage modulus at reflow temperature, and depressed equilibrium water uptake for the epoxy packaging materials. The light transmittance of encapsulants differed after thermal and UV aging. Compared with Neat ECC and Neat HBADGE, the HBADGE-modified encapsulants endowed LED devices with good performance and high reliability.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2012
·
IF 3.696
Bo Wu,Chunliang Li,Haiyang Yang,Guangming Liu,Guangzhao Zhang
Poly(sodium 4-styrene sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDDA) are flexible polyelectrolytes, whereas sulfated chitosan (SC) and cationic guar gum (CGG) are semiflexible polyelectrolytes. By use of a quartz crystal microbalance with dissipation (QCM-D), a zeta potential analyzer (ZPA), and atomic force microscopy (AFM), we have investigated the growth of PSS/PDDA, PSS/CGG, SC/PDDA, and SC/CGG multilayers as a function of NaCl concentration (CNaCl). For the same layer number, the changes of frequency (−Δf) and dissipation (ΔD) regarding PSS/PDDA multilayer increase with CNaCl, whereas −Δf and ΔD for SC/CGG multilayer increase at CNaCl < 0.1 M and decrease at CNaCl > 0.1 M as CNaCl increases. In the cases of PSS/CGG and SC/PDDA multilayer, for the same layer number, −Δf and ΔD increase with CNaCl in the range of CNaCl < 0.5 M, and they decrease with the increasing CNaCl in the case of SC/PDDA multilayer but slightly change for the PSS/CGG multilayer at CNaCl > 0.5 M. QCM-D studies indicate that the growth of multilayers as a function of salt concentration is determined by the delicate balance between the weakening of electrostatic repulsion between identically charged groups and the decrease of electrostatic attraction between neighboring layers. ZPA and AFM measurements demonstrate that the extent of surface charge overcompensation and the surface morphology of the multilayers are controlled by the chain conformation.
研究领域:
材料科学
·
表面化学
·
生物物理学
✓ 已验证
DOI
高影响因子
Membranes
·
2025
·Vol. 15
·期 5
·128
·
IF 3.6
Yingxiu Wu,Haiyan Guo,Bingyu Zhao,Yuxiu Yu,Yaodong Liu,Shouchun Zhang
Carbon molecular sieve (CMS) membranes demonstrate considerable advantages and significant potential in the separation of CO2and CH4. Nevertheless, current research predominantly emphasizes the enhancement of CMS membranes through the incorporation of rigid structures and chain spatial stacking. The role of flexible structures in this context remains inadequately understood. To address this gap, we introduced long-chain polydimethylsiloxane (PDMS) and copolymerized it to synthesize polyimide that combines rigid and flexible frameworks. This approach enabled us to investigate the impact of flexible structures on the structure and properties of carbon membranes by varying the PDMS content. The findings indicated that flexible PDMS significantly influenced the thermal decomposition behavior of polyimide and facilitated in situ silicon doping within the carbon membranes, thereby modifying the pore characteristics of the carbon film. Specifically, with a 10% addition of PDMS, the CO2permeability of the CMS membrane reached 9556 Barrer, representing an enhancement of 103.9% and surpassing the 2019 upper bound for CO2/CH4separation. Furthermore, the effect of pyrolysis temperature was also examined. Ultimately, this study offers a novel perspective on regulating the structural and performance characteristics of carbon membranes through the integration of long-chain flexible structures.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2024
·
IF 3.9
Yijia Guan,Hui Guo,Xiaofeng Jia,Jieyi Qin,Yue Yang,Kun Cao,Tao Li,Jianguo Liao,Yanru Zhang
Shape memory polymers (SMPs) are novel kinds of smart materials whose shape can be changed in external conditions such as heat stimulus. Due to their excellent structural versatility and high elastic strain, they have important applications in the field of biomaterials. Here, a series of amorphous shape memory polymer materials are prepared and their shape memory properties and glass transition temperature ( T g ) are also investigated. A special kind of epoxy polymer, whose shape can be changed at around physiological temperature, is synthesized by regulating the crosslinking density and introducing flexible aliphatic epoxy chains. The shape memory function of this epoxy polymer is studied by deformation test. In addition, to explore their application in the field of biomedical materials, the biocompatibility of the materials are evaluated, including the effects on the erythrocyte hemolysis rate and cell activity. The experimental results show that this kind of epoxy polymer has good shape memory function and biocompatibility. Graphical Shape memory polymers (SMPs) are novel kinds of smart materials whose shape can be changed in external conditions such as heat stimulus. Here, a special kind of epoxy polymer with good shape memory function and biocompatibility, whose shape can be changed at around physiological temperature, is synthesized by regulating the crosslinking density and introducing flexible aliphatic epoxy chains.
研究领域:
材料科学
·
生物医学工程
✓ 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）