PHASE SEPARATION AND MICROVOID FORMATION AT PHASE INTERFACES OF HYDROPHOBIC-HYDROPHILIC POLYMER BLENDS DURING WET PROCESSING

In this paper,morphological structure,thermodynamic compatibility and relationship be-tween porosities and blend ratios of the wet coagulated PU/PVA sheets were studied by meansof observation of scanning electronic micrographies,tests of dynamic mechanical properties,moisture regain and vapor permeability.Furthermore,the formation of microvoids at interfacesof separated phases was discussed and a microvoid formation mechanism at phase interfaces ofhydrophobic-hydrophilic blends was suggested and compared with that ofhydrophobic-hydrophobic blends.

Reconcile the contradictory wettability requirements for the reduction and oxidation half-reactions in overall CO_(2) photoreduction via alternately hydrophobic surfaces

The overall photocatalytic CO_(2) reduction reaction(OPCRR)that can directly convert CO_(2) and H_(2)O into fuels represents a promising renewable energy conversion technology.As a typical redox reaction,the OPCRR involves two half-reactions:the CO_(2) reduction half-reaction(CRHR)and the water oxidation half-reaction(WOHR).Generally,both half-reactions can be promoted by adjusting the wettability of catalysts.However,there is a contradiction in wettability requirements for the two half-reactions.Specifically,CRHR prefers a hydrophobic surface that can accumulate more CO_(2) molecules on the active sites,ensuring the appropriate ratio of gas-phase(CO_(2))to liquid-phase(H_(2)O)reactants.Conversely,the WOHR prefers a hydrophilic surface that can promote the departure of the gaseous product(O_(2))from the catalyst surface,preventing isolation between active sites and the reactant(H_(2)O).Here,we successfully reconciled the contradictory wettability requirements for the CRHR and WOHR by creating an alternately hydrophobic catalyst.This was achieved through a selectively hydrophobic modification method and a charge-transfer-control strategy.Consequently,the collaboratively promoted CRHR and WOHR led to a significantly enhanced OPCRR with a solar-to-fuel conversion efficiency of 0.186%.Notably,in ethanol production,the catalyst exhibited a 10.64-fold increase in generation rate(271.44μmol g^(-1)h~(-1))and a 4-fold increase in selectivity(55.77%)compared to the benchmark catalyst.This innovative approach holds great potential for application in universal overall reactions involving gas participation.

HYDROPHOBICITY－HYDROPHILICITY BALANCE RELATIONSHIPSFORCOLLECTORLESSFLOTATIONOFSULPHIDEMINERALS

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Hydrophilic/hydrophobic characters of antimicrobial peptides derived from animals and their effects on multidrug resistant clinical isolates

Multidrug resistant（MDR） pathogen infections are serious threats to hospitalized patients because of the limited therapeutic options. A novel group of antibiotic candidates, antimicrobial peptides（AMPs）, have recently shown powerful activities against both Gram-negative and Gram-positive bacteria. Unfortunately, the viability of using these AMPs in clinical settings remains to be seen, since most still need to be evaluated prior to clinical trials and not all of AMPs are potent against MDR clinical isolates. To find a connection between the characteristics of several of these AMPs and their effects against MDR pathogens, we selected 14 AMPs of animal origin with typical structures and evaluated their in vitro activities against clinical strains of extensive drugresistant Acinetobacter baumannii, methicillinresistant Staphylococcus aureus, extended spectrum β-lactamase-producing Pseudomonas aeruginosa and extended spectrum β-lactamase-producing Escherichia coli. Our results showed that these peptides＇ hydrophilic/hydrophobic characteristics, rather than their secondary structures, may explain their antibacterial effects on these clinical isolates. Peptides that are amphipathic along the longitudinal direction seemed to be effective against Gramnegative pathogens, while peptides with hydrophilic terminals separated by a hydrophobic intermediate section appeared to be effective against both Gramnegative and Gram-positive pathogens. Among these, cathelicidin-BF was found to inhibit all of the Gram-negative pathogens tested at dosages of no more than 16 mg/L, killing a pandrug-resistant A. baumannii strain within 2 h at 4×MICs and 4 h at 2×MICs. Tachyplesin III was also found capable of inhibiting all Gram-negative and Gram-positive pathogens tested at no more than 16 mg/L, and similarly killed the same A. baumannii strain within 4 h at 4×MICs and 2×MICs. These results suggest that both cathelicidin-BF and tachyplesin III are likely viable targets for the development of AMPs for clinical uses.

Hydrophobic versus hydrophilic acrylic intraocular lens on posterior capsule opacification: a Meta-analysis

AIM: To conduct a Meta-analysis pooling randomized controlled trials(RCTs) to compare hydrophobic with hydrophilic acrylic intraocular lenses in terms of posterior capsule opacification(PCO) development.METHODS: Electronic databases including PubMed,Embase, and the Cochrane Library were queried from their starting till January 2020. RCTs investigating the impact of hydrophobic versus hydrophilic acrylic intraocular lenses on PCO were considered eligible in this study. The pooled effect estimates were calculated using the random-effects model.RESULTS: Thirteen RCTs comprising of 939 patients(1263 eyes) were covered in this study. Patients with hydrophobic acrylic intraocular lenses had a lower PCO score than those with a hydrophilic acrylic intraocular lenses [standard mean difference:-1.80;95% confidence interval(CI):-2.62 to-0.98;P<0.001]. Moreover, the frequency of neodymium-doped yttrium aluminum garnet(Nd:YAG)capsulotomy in patients with hydrophobic acrylic intraocular lenses was significantly lower than patients with hydrophilic acrylic intraocular lenses(relative risk: 0.38;95%CI: 0.20-0.71;P=0.003).CONCLUSION: These findings suggest that hydrophobic acrylic intraocular lenses are superior to hydrophilic acrylic intraocular lenses in patients after cataract surgery due to lower PCO score and reduced Nd:YAG capsulotomy. While similar studies are conducted by other researchers, the present study conducted subgroup analyses that show superior results with hydrophobic lenses in trials conducted in western countries.

STUDY ON A HYDROPHOBIC-HYDROPHILIC GRADIENT ROD

A hydrophobic-hydrophilic gradient rod with a length of 40 mm and a diameter of 3 mm was prepared by heating a polymethylsilsesquioxane rod in a cylindrical stove with temperature gradient. The rod was thus pyrolyzed under a temperature gradient condition. The organic end of the gradient rod appears hydrophobic with a contact angle of 109.9° while the other end is hydrophilic with a contact angle of 62.4°. The gradient chemical structure and the gradient microstructure along the rod were characterized by FTIR and SEM, respectively.

A Metal-organic Framework with Alternately Hydrophilic and Hydrophobic Layers Based on Tetrazole Derivative:Synthesis,Structure and Luminescent Property

A new metal-organic framework based on ethyl 1H-tetrazole-5-acetate （Hetza）, [Ag4（etza）4] （1）, has been synthesized and characterized by elemental analysis, IR, thermal gravimetric and X-ray structural analysis. Crystal data for the title complex are as follows： triclinic system, space group P1 with a = 11.0771（6）, b = 11.6636（6）, c = 13.2925（8）, a = 102.3710（10）, β =103.3810（10）, γ = 90.0890（10）°, V = 1629.60（16） A3, Mr = 1052.06, Z = 2, F（000） = 1024, Dc = 2.144 g/cm3, μ（MoKa） = 2.438 mm^-1, the final R = 0.0538 and wR = 0.1475 （I 〉 2σ（I））. Complex 1 adopts the （4.82） topological network and the alternately hydrophilic-hydrophilic and hydropho- bic-hydrophobic arrangements. The luminescent properties of complex 1 and the free Hetza ligand have been studied in the solid states.

Synthesis and Characterization of a HydrophilicHydrophobic IPN Composed of Poly(vinyl alcohol)and Polystyrene

A hydrophilic/hydrophobic interpenetrating polymer network （IPN） of poly （vinyl alcohol） / polystyrene was prepared by conversion of the IPN of poly （vinyl acetate）/polystyrene. The hydrophilic/hydrophobic IPN was characterized by FT-IR and DSC, and the swelling ratios of the IPN in different solvents were measured.

High drug loading hydrophobic cross-linked dextran microspheres as novel drug delivery systems for the treatment of osteoarthritis

Drug delivery via intra-articular(IA)injection has proved to be effective in osteoarthritis(OA)therapy,limited by the drug efficiency and short retention time of the drug delivery systems(DDSs).Herein,a series of modified cross-linked dextran(Sephadex,S0)was fabricated by respectively grafting with linear alkyl chains,branched alkyl chains or aromatic chain,and acted as DDSs after ibuprofen(Ibu)loading for OA therapy.This DDSs expressed sustained drug release,excellent anti-inflammatory and chondroprotective effects both in IL-1βinduced chondrocytes and OA joints.Specifically,the introduction of a longer hydrophobic chain,particularly an aromatic chain,distinctly improved the hydrophobicity of S0,increased Ibu loading efficiency,and further led to significantly improving OA therapeutic effects.Therefore,hydrophobic microspheres with greatly improved drug loading ratio and prolonged degradation rates show great potential to act as DDSs for OA therapy.

Preparation and Hydrophilicity of Copolymerization of Chitosan Selectively Grafted by Polyethylene Glycol

Copolymerization of chitosan selectively grafted by polyethylene glycol was prepared. Chitosan was selectively grafted by monomethoxy polyethylene glycol（mPEG-OH）, which contained a hydroxyl group combining with hexamethylene diisocyanate（HDI） to form a novel macromonomer namely monomethoxy polyethylene glycol isocyanate（mPEG-NCO） containing a isocyanate group with higher chemical activity in ethyl glyoxalate solution absolutely without water. The selective grafted copolymerization of Chitosan with mPEG-NCO was conducted under heterogeneous conditions as suspension in dimethylformamide. The hydrophilic copolymers of chitosan were prepared by condensation reaction of isocyanate group on mPEG- NCO with hydroxy groups on chitosan chains because amino groups on chitosan chains were protected by complexion formation with copper ions. The effect of reaction condition on the grafting extents was discussed. Swelling properties of mPEG-g-CS were researched. The graft copolymer mPEG-g-CS was characterized by the infrared spectra. The experimental result showed that the copper ions were very effective to protect amino groups from condensation reaction. The swelling degree in water increases with adding of grafting ratio. The maximum swelling degree was up to above 132% when the grafting ratio was about 270%. The graft copolymer can be soluble partially in pure water.

The choice of antimicrobial polymers:Hydrophilic or hydrophobic?

Owing to the spread of COVID-19,it is difficult to ignore the existence and importance of antimicrobial polymers(AMPs)because most protective appliances are made of polymers.Generally,bacteria prefer hydrophilic compounds,while fungi prefer hydrophobic ones.In recent decades,AMPs have made significant strides due to the versatile design of the functional groups or units for hydrophilic,hydrophobic,or amphiphilic performances.This review summarizes the advances of AMPs itself from the perspective of their wettability.Moreover,this study aims to clarify how the functional groups determine the interaction between the polymer and microorganisms directly affects the antimicrobial efficacy of the designed polymers.Based on the advances,the challenges and outlooks of AMPs from the perspective of wettability are systematically discussed to build a bridge between the structural design of AMPs and the requirements of practical applications.

Surface-state controlled synthesis of hydrophobic and hydrophilic carbon dots

It is of great significance to synthesize carbon dots(CDs)with desirable hydrophilicity for the ever-growing application of CDs in different fields.In this study,the hydrophilic and hydrophobic CDs were facilely prepared by solvothermal treatment of o-dihydroxybenzene and urea in N,N-dimethylformamide(DMF).Optimization experiments revealed that the solvothermal temperature has a great impact on the surface states of the CDs.The hydrophobic CDs with a contact angle of 110.7°was obtained at 200℃.The structural and optical characterizations,along with theoretical calculations elucidated that the lipophilic nature of the CDs was resulting from the formation of polymer chains.The presence of extended conjugated sp^(2)-domains and amino groups contributed to the red emission of the CDs synthesized at low reaction temperatures(160-200℃).With the further increase of solvothermal temperature,the hydrophobic CDs were gradually transformed to the hydrophilic state accompanying the blue shift of the fluorescence of the CDs.The highly hydrophilic CDs with a contact angle of 25.9°were obtained at 240℃ due to the increased formation of hydrophilic functional groups on the surface of CDs.The red emissive CDs exhibited a sensitive color and fluorescence response to ethanol content while the fluorescence of the blue emissive CDs remained constant.By combining the two kinds of CDs,a dual-emission sensor was constructed,which was successfully applied for the evaluation of the alcoholic strength in commercial Baijiu commodities in both fluorometric and colorimetric modes.

Large-scale Patterning of Hydrophobic Silicon Nanostructure Arrays Fabricated by Dual Lithography and Deep Reactive Ion Etching

We describe a simple but efficient technique to fabricate large-scale arrays of highly ordered silicon nanostructures. By coupling dual lithography using light of 351.1 nm wavelength with deep reactive ion etching(DRIE), silicon nanostructures of excellent regularity and uniform coverage were achieved. The proposed nanofabrication method not only simplified the nanofabrication process but also produced highaspect-ratio(higher than 15) nanostructures. The scalloping problem was also controlled by regulating DRIE parameters. The process is rapid, cheap, examined to optimize the fabrication process, and has the potential to be scaled up to large areas. The contact angle of a water droplet atop the surface is larger than 150?.Moreover, by coupling black silicon process with DRIE-based microfabrication, three-dimensional nano/nano dual-scale structures which show robust and stable hydrophobicity have been achieved. This process opens new application possibilities in optical, photoelectric, microelectronic, catalytic and biomedical applications.

The Rise and Fall of the Hydrophobic Effect in Protein Folding and Protein-Protein Association, and Molecular Recognition

In the beginning everything was explained in Biochemistry in terms of hydrogen-bonds (HB). Then, the devastating blow, known as the HB-inventory argument came;hydrogen bonding with water molecules compete with intramolecular hydrogen-bonds. As a result, the HBs paradigm fell from grace. The void created was immediately filled by Kauzmann’s idea of hydrophobic (HφO) effect which reigned supreme in biochemical literature for over 50 years (1960-2010). Cracks in the HB-inventory argument on one hand, and doubts about the adequacy of Kauzmann’s model for the HφO effect, have led to a comeback of the HBs, along with a host of new hydrophilic (HφI) effects. The HφO effects lost much of its power - which it never really had - in explaining protein folding and protein-protein association. Instead, the more powerful and richer repertoire of HφI effects took over the reins. The interactions also offered simple and straightforward answers to the problems of protein folding, and protein-protein association.

Effect of Gangue Minerals on Hydrophobic Recovery of Gold

In this paper, the effect of gangue minerals on the hydrophobic recovery of gold is being investigated using ores obtained from the active small scale gold mining sites in Tanzania. Gold ores of different gangue contents were tested. The effects of silica gangue and high sulphide gangue on gold attachment were examined including the effect of surface activators (potassium amyl xanthate) and the possibility of depressing the effects of gangue using reagents. The results were evaluated in terms of gold recovery, volumes and grade of concentrates formed. There was no change in gold recoveries when the amount of oxide gangue (quartz) in the ore was increased, indicating absence of competition between gold and quartz gangue. High sulphide contents in the ore above 6% reduced gold recoveries considerably. It was noted that potassium amyl xanthate surfactants increased the attachment of both gold and the sulphide gangue. Using lime at pH 10 it was possible to depress the sulphide gangue which is mainly pyrite and hence increased gold recoveries considerably.

医用介入导丝用疏水和亲水涂层的研究进展

医用介入导丝被广泛应用于各类介入手术,是目前经皮冠状动脉成形(PTCA)术及经皮血管成形术(PTA)中常用的医疗器械之一。在医用介入导丝表面添加亲水或疏水涂层,可以减小导丝在临床应用中的组织摩擦和组织损伤,有效提高导丝的通过性、抗菌性和生物相容性,减少炎症。综述了近年来国内外医用介入导丝亲水和疏水涂层材料,介绍了这些涂层的机理、附着力优化、抗菌修饰等方面内容,重点介绍了聚四氟乙烯、聚乙烯吡咯烷酮、聚丙烯酰胺、聚乙二醇、聚对二甲苯等涂层材料体系的研究进展,介绍了不同材料体系在医用导丝亲水和疏水涂层的作用机理和实际应用,同时介绍了亲疏水涂层的制备工艺,重点阐述了层层自组装、紫外光接枝、等离子体接枝和化学气相沉积等制备方法的可操作性、优势和劣势。最后在总结前人研究成果的基础上,对医用介入导丝涂层的现状及面临的问题进行了探讨,并对医用介入导丝涂层的发展方向及提高涂层综合性能等方面进行了展望。

一步水热改性石英砂支撑剂及性能研究

为提高石英砂在压裂液中的分散稳定性,采用十六烷基三甲基氯化铵(CTAC)对传统石英砂表面进行改性。结果表明,CTAC质量分数为0.6%,在80℃中性条件下与石英砂反应120 min,可以使石英砂的沉降速度降低44.85%。改性前后石英砂与水的接触角由28.233°增至87.853°,表明石英砂表面的疏水性有大幅度改善,石英砂颗粒与水分子之间的排斥力增大。表面自由能由83.342 mJ/m^(2)降至22.379 mJ/m^(2),表面自由能降低使系统更加稳定,从能量的角度解释了改性后石英砂沉降速度降低的原因。改性后石英砂的zeta电位是改性前的2倍,石英砂颗粒之间的静电斥力明显增大,从而使颗粒之间不容易聚沉,体系更加稳定。

基于改性逆向热致相分离法聚砜微孔膜的制备与性能

针对逆向热致相分离法(RTIPS)制备聚砜(PSF)微孔膜成膜体系稳定性较差的问题,首先对亲水性的端羟基型超支化聚酯(HBPE)进行封端,然后以PSF为膜材料,通过添加亲水剂封端HBPE构建四元低临界共溶温度(LCST)成膜体系PSF/HBPE/N,N-二甲基乙酰胺/聚乙二醇400,采用改性逆向热致相分离法(m-RTIPS)一步制备了亲水性PSF微孔膜。对封端HBPE进行了结构分析和分子量测试,分析了HBPE的封端率对四元成膜体系浊点和黏度的影响,研究了HBPE的封端率对PSF微孔膜的形貌、渗透性、亲水性、抗污染性和力学性能的影响。结果表明,成功对HBPE进行了封端,封端后HBPE的分子量增加;成膜体系的浊点和黏度随HBPE封端率的升高而增大,但黏度上升的幅度较小;3种添加不同封端率HBPE的PSF微孔膜的纯水通量、截留率、亲水性和力学性能都优于纯PSF微孔膜;随HBPE封端率的增加,膜的纯水通量下降,但截留率差别很小。当HBPE封端率为30%时,PSF膜纯水通量恢复率达88%,抗污染性最佳。添加不同封端率HBPE都可制得表面多孔的膜,当HBPE封端率为50%时,PSF膜具有全双连续结构的形貌,其拉伸强度、拉伸弹性模量和断裂伸长率分别为4.86,143.92 MPa和22.68%,综合力学性能优异。

表面润湿性对球体斜射入水过程的影响研究

针对球体表面润湿性对倾斜入水空泡演化过程及球体动力特性的影响开展研究,以便能够进一步理解润湿性对入水过程的影响并且能够为多种情况下的入水现象提供理论依据.基于球体入水过程空泡形态观察、采集与测量实验平台,分析了亲水性和疏水性球体入水过程中入水喷溅和空泡的演变规律,并深入讨论了不同速度下球体表面润湿性对球体入水过程中动力特性的影响.研究表明,不同表面润湿性球体在入水过程中的喷溅及入水空泡演化与动力特性存在明显区别.在相同入水速度下,亲水性球体的三相接触点远高于疏水性球体,而喷溅的高度却低于疏水性球体,但该差异随入水速度的增加反而减小.随着入水速度的增大,亲水性球体依次经历了无空泡、浅闭合和面闭合3种闭合方式,而疏水性球体先后只出现了深闭合和面闭合两种.但是,随着入水速度的增加,球体表面润湿性对空泡演化过程的影响逐渐减弱,当速度增加到11.25 m/s时,二者不存在区别.同时发现,在入水过程中,在相同速度下生成入水空泡较无入水空泡其总流动阻力系数降低49.94%;亲水性球体生成空泡体积更小,空泡带来的附加质量力也更小,减阻效果更好.

智能表面可润湿性材料的研究进展

润湿现象广泛存在于自然界和工程应用中,智能表面可润湿性材料日益成为研究的热点,近年来引起了人们的广泛关注。综述了润湿性的理论模型、疏水/亲油行为理论和亲水/水下超疏油理论,同时对近些年来国内外可润湿性的不同响应系统(电、pH、光、热、离子等响应刺激系统)进行了综述,改变响应材料的表面和化学性质,导致材料可润湿性的改变。展望了未来可润湿性的研究方向,对润湿表面理论和应用方面存在的一些挑战进行了总结和建议。