Novel low‐dielectric‐constant fluorine‐functionalized polysulfone with outstanding comprehensive properties

In this work, a series of fluorine‐functionalized polysulfone (F‐PSU) copolymers with intrinsic low dielectric constants (low ε) are reported, which are derived from the polycondensation reaction of 4,4′‐dichlorophenyl sulfone with bisphenol A and bisphenol F (BPF) compounds. The resulting F‐PSU copolymers show high glass transition temperatures (T_g) varying from 187 to 201 °C and are thermally stable up to 500 °C under an N₂ atmosphere. The introduction of BPF units into the PSU copolymers imparts enhanced hydrophobic properties to the F‐PSU films with increased water contact angle values from 66.2° to 93.7°. Moreover, the dielectric constant and dielectric loss of the F‐PSU (sample V) film are as low as 2.2 and 0.003 at 1 kHz, respectively. Interestingly, the dielectric properties are relatively stable to near the glass transition temperature, which is because of the existence of BPF structures in the molecular backbone. Furthermore, the F‐PSU copolymers are soluble in common solvents and can be readily fabricated into flexible transparent films by the spin casting method. © 2020 Society of Chemical Industry     

Synthesis and characterization of cellulose nanowhisker-reinforced-poly(ε-caprolactone) scaffold for tissue-engineering applications

Poly(ε-caprolactone) (PCL) is a bioresorbable and biocompatible polymer with assorted medical applications. However, remarkable hydrophobicity and nonosteoconductivity have stood as a barrier to limit its applications. The present study aims to modify the bulk characteristics of PCL to develop a polymeric scaffold with adequate structural and mechanical properties to support regenerated tissues. For this purpose, functionalized bacterial cellulose nanowhiskers (BCNW-g-βCD-PCL₂₀₀₀) are synthesized. Reinforcing PCL matrix with 4 wt % of the nanowhiskers resulted in a bionanocomposite with promoted bulk properties. Compared to neat PCL, the obtained bionanocomposite shows improvements of 115 and 51% in tensile strength and Young's modulus, respectively; 20% increase in hydrophilicity; 7% increase in degradation rate; and 6% decrease in crystallinity. Gas foaming/combined particulate leaching technique is used to develop highly porous structures of 86–95% porosity with interconnected macropores of mean pore diameters of 250–420 μm. Porous scaffolds showed compression modulus values of 5.3–9.1 MPa and would have promising applications in regenerative medicine. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48481.     

孪尾疏水单体改性聚丙烯酰胺的合成及性能表征

以十二烷基磺酸钠胶束溶液为表面活性剂,将孪尾疏水单体N,N-二乙基丙烯酰胺增溶其中,再以过硫酸钾为引发剂,与丙烯酰胺和丙烯酸钠通过胶束共聚法制备了疏水改性聚丙烯酰胺(HMPAM)。利用FTIR、1H NMR、TG、荧光光谱和流变测试等方法表征了HMPAM的结构,并研究了其水溶液的流变性能。表征结果显示,HMPAM中存在孪尾的乙基结构,热稳定性较好。实验结果表明,当HMPAM含量低于0.5 g/L时,其对溶液极性影响不大;当HMPAM含量高于0.5 g/L时,溶液极性降低。HMPAM溶液为非牛顿流体,随HMPAM含量的增大,聚合物的孪尾基团发生缔合作用的几率增大,溶液表观黏度增大。HMPAM具有较好的触变性和耐温性能。     

氯化镧对镁合金表面疏水化处理的影响

研究了氯化镧对镁合金疏水膜耐蚀性的影响。采用中性盐雾试验和电化学试验测试了疏水膜的耐蚀性,并采用扫描电子显微镜观察了疏水膜的表面形貌。结果表明:氯化镧对镁合金疏水膜有一定的改性作用,使膜层由乳突状结构转变为层片状结构,进而使膜层由疏水表面转变为超疏水表面,其接触角可达153°。另外,添加氯化镧后疏水膜的盐雾时间延长至109.0 h,耐蚀性大幅提高。     

Novel Flower-Like ZnO Hybridized with Acrylic Ester Resin for Enhanced Oil Absorption Properties

The acrylic ester resins have potential applications in for treatment of oily wastewater due to their high oil retention capacity and excellent cycle performance. Herein, a novel acrylic ester hybrid resins composed by poly(n-butylacrylate-co-styrene) resins and flower-like ZnO clusters were prepared using a combination of hydrothermal and suspension polymerization. The hybrid resins can remove a broad variety of oils from water with the maximum oil absorption performance of 30.87?g/g. More importantly, the hybrid resins are reversible and maintain high oil absorption properties after oils absorption-regeneration, making them promising candidates for treatment of oily wastewater.     

Effective Release of Intracellular Enzymes by Permeating the Cell Membrane with Hydrophobic Deep Eutectic Solvents

An efficient and green method is crucial for the recovery of intracellular biological products. The major drawbacks of the conventional cell disruption method are nonselectivity and enzyme denaturation. The permeability of hydrophobic deep eutectic solvents (DESs) to the cell membrane was studied, for the first time, and then hydrophobic DESs were innovatively applied to release intracellular enzymes from recombinant Escherichia coli. After optimization, a DES suspension of l -menthol/oleic acid (0.5 %, v/v) showed the highest release yield of intracellular enzyme. Compared with that released by sonication, a release yield of phospholipase D (PLD) of up to 114.58 % was achieved, and the specific activity was increased by 1.96 times. The microstructure of the cell membrane under different treatments was observed by using an electron microscope to understand the permeation of DESs to the cell membrane. The feasibility and applicability of the proposed release method in industrial applications were also demonstrated. The effective and green release method of intracellular enzymes developed herein has bright prospects for industrial application to replace traditional cell disruption methods. A preliminary study on the permeability of hydrophobic DESs to the cell membrane showed that there would be a potential application prospect of hydrophobic DESs not only in releasing intracellular contents, but also in seeking new green penetrating agents.     

Preparation and properties of fluorinated silicon two‐component polyurethane hydrophobic coatings

A polyurethane (PU) hydrophobic coating was prepared by the two‐component method, polycarbonate diol and isophorone diisocyanate becoming a two‐phase composition. The PU films with hydrophobic surface were prepared by establishing a rough structure on the surface of silica (SiO₂) modified with silane coupling agents (γ‐(2,3‐epoxypropoxy)propytrimethoxysilane (KH560) and (heptadecafluoro‐1,1,2,2‐tetradecyl)trimethoxysilane (FAS)). First, the surface of SiO₂ was covered by a layer of hydrophobic methyl and fluorocarbon (C–F) groups. Then, the SiO₂ and modified SiO₂ were obtained by the introduction of KH560 and FAS with the silanol reaction by ultrasonic stirring. The effect of SiO₂ and modified SiO₂ on the structure and hydrophobic properties of PU was investigated by a series of test instruments. The results showed that the introduction of SiO₂ and modified SiO₂ was beneficial for increasing the roughness of the PU coating surface; the roughness of FAS/SiO₂‐PU could reach up to 14.790 nm, four times better than pure PU. A hydrophobic modified PU coating with water contact angle 123° was fabricated by using the hydrophobic C–F group FAS as a low surface energy material and establishing a micro rough structure on the surface of PU. Moreover, PU modified with KH560 and FAS can reduce the glass transition temperature (T_g) of soft segments, resulting in improvement of micro‐phase separation. © 2020 Society of Chemical Industry     

Hydrophobizing polyether sulfone membrane by sol-gel for water desalination using air gap membrane distillation

ABSTRACT

The hydrophobic polyether sulfone membranes were prepared by the sol-gel method to be applied in an air gap membrane distillation setup for desalination. The surface modifications were carried out using Trimethylsilyl chloride (TMSCl) and Methyltrimethoxysilane (MTMS) solutions. The membranes were characterized using Attenuated Total Reflection Infrared (ATR-IR) spectroscopy, Scanning Electron Microscopy (SEM), and Optical Contact Angle (OCA) methods. The effects of membrane preparation as well as operating conditions such as temperature difference, salt concentration, feed rotation speed, and cold-side temperature on membrane performance were investigated using central composite design method. It was found that feed temperature has the largest effect among the parameters on the permeation flux. The flow rate and salt rejection of the membrane in the optimum conditions were 4.47 Kg m^?2 h^?1 and 99.37%, respectively.     

憎水处理页岩陶粒配制高性能轻集料混凝土及其性能的研究

普通页岩陶粒吸水率偏大，对其进行表面憎水处理，可有效降低其吸水率，满足高性能轻集料混凝土(HVLC)配制的需要。本文利用经过表面憎水处理的普通页岩陶粒作为粗集料，配制出28天抗压强度高于30MPa且抗渗等级大于P12的高性能轻集料混凝土，并对其拌合物性能、强度和抗渗性等进行了分析研究。     

建筑防水粉

介绍了以轻质碳酸钙为基料的两种具有较好防水性能的建筑防水粉，阐述了这两种防水粉的合理配比及制备的工艺条件。