Hydrophobic State Research Articles

Leveraging novel innovative thermoresponsive polymers in microneedles for targeted intradermal deposition

Microneedles have garnered considerable attention over the years as a versatile pharmaceutical platform that could be leveraged to deliver drugs into and across the skin. In the current work, poly (N-isopropylacrylamide) (PNIPAm) is synthesized and characterized as a novel material for the development of a physiologically responsive microneedle-based drug delivery system. Typically, this polymer transitions reversibly between a swell state at lower temperatures and a more hydrophobic state at higher temperatures, enabling precise drug release. This study demonstrates that dissolving microneedles patches made from PNIPAm, incorporating BIS-PNIPAm, a crosslinked polymer variant, exhibit enhanced mechanical properties, evident from a smaller height reduction in microneedle (∼10 %). Although microneedles using PNIPAm alone were achievable, it displayed poor mechanical strength, requiring the inclusion of additional polymeric excipients like PVA to enhance mechanical properties. In addition, the incorporation of a thermoresponsive polymer did not have a significant (p > 0.05) impact on the insertion properties of the needles as all formulations inserted to a similar depth of 500 µm into ex vivo skin. Furthering this, the needles were loaded with a model payload, 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindodicarbocyanine perchlorate (DID) and the deposition of the cargo was monitored via multiphoton microscopy that showed that a deposit is formed at a depth of ≈200 µm. Also, it was revealed that crosslinked-PNIPAm (Bis-PNIPAm) formulations exhibited notable skin accumulationof the dye only after 4 h, independent of the excipient matrix used. This phenomenon was absent in non-crosslinked PNIPAm formulations, indicating a deposit formation in Bis-PNIPAm microneedle formulation. Collectively, this proof-of-concept study has advanced our understanding on the possibility to use PNIPAm for dissolving microneedle fabrication which could be harnessed for the deposition of nanoparticles into the dermis, for extended drug release within the skin.

A review on application areas and surface geometry in superhydrophobic materials

Superhydrophobic surfaces offer many advantages beyond just being hydrophobic (water repellent) to the surface. The superhydrophobic property can be achieved by artificially creating geometric structures on the material surface. These geometric structures reduce the contact area between the liquid and the surface. The contact angle between the liquid and the surface gives rise to two conditions: hydrophobic and hydrophilic. If the contact angle between the surface and the liquid is above 90 degrees, a hydrophobic state occurs. If the angle is below 90 degrees, the surface is in a hydrophilic state. One of these two states is determined depending on the need and provides alternative solutions for many problems that currently await engineering interventions. Scientific studies in the field of superhydrophobia are increasing day by day. Interest in superhydrophobia is expected to grow further, as it offers environmentally friendly and economical solutions to ongoing challenges in various sectors. Superhydrophobic materials also offer a method of preventing icing due to their ability to prevent liquid retention on the material surface through their water repellent properties. Since the reduction of the contact area between the liquid and the material surface on superhydrophobic surfaces leads to a decrease in the friction factor, the friction of the flow on the material will also decrease. These properties of superhydrophobic materials generate interest in sectors such as aviation and marine. This study describes the properties of superhydrophobic surfaces created through various methods on materials, focusing on applications such as anti-icing and reduction of friction factor.

Nanogels with tailored hydrophobicity and their behavior at air/water interfaces.

The interfacial behavior of micro-/nanogels is governed to a large extent by the hydrophobicity of their polymeric network. Prevailing studies to examine this influence mostly rely on external stimuli like temperature or pH to modulate the particle hydrophobicity. Here, a sudden transition between hydrophilic and hydrophobic state prevents systematic and gradual modulation of hydrophobicity. This limits detailed correlations between interfacial behavior and network hydrophobicity. To address this challenge, we introduce a nanogel platform that allows accurate tuning of hydrophobicity on a molecular level. For this, via post-functionalization of active ester-based particles, we prepare poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) nanogels as a hydrophilic benchmark and introduce gradually varied amounts of hydrophobic propyl or dodecyl moieties to increase the nanogel hydrophobicity. We study the deformation and arrangement of these particles at an air/water interface and correlate the results with quantitative measures for nanogel hydrophobicity. We observe that increasing hydrophobicity of nanogels, either by increasing the hydrophobic moiety ratio or the alkyl chain length, leads to decreased particle deformability and aggregation of an interfacially-adsorbed monolayer. Contrary to what may be intuitively assumed, these changes are not gradual, but rather occur suddenly above a threshold in hydrophobicity. Our study further shows that the effect of hydrophobicity affects the nanogel properties differently in bulk and when adsorbed at liquid interfaces. Thus, this study establishes the transition of interfacial behavior between soft gel-like particles to a solid spherical morphology triggered by the increase in hydrophobicity.

Grafting of Poly(N-Vinylcaprolactam) in polyurethane by gamma radiation

Poly (N-vinylcaprolactam) (PNVCL) is a thermoresponsive, biocompatible, non-toxic polymer with a phase transition temperature from hydrophilic to hydrophobic state (Tpt) close to the physiological one. This temperature is influenced by PNVCL molar mass and its copolymerization. In this work, gamma radiation at doses of 5 and 20 kGy was used to graft PNVCL chains onto films of thermoplastic polyurethane (TPU). PNVCL homopolymers were also developed by gamma radiation at the same conditions. The materials were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), viscometry and thermogravimetric analaysis (TGA). PNVCL grafting enabled thermoresponsive character to TPU films, as observed by changes in water-surface contact angles above and below Tpt. The Tpt of the developed homopolymers determined by cloud point and rheological analysis was close to 30 °C. These results demonstrated the feasibility of developing a graft copolymer with thermoresponsive properties, with the innovation of grafting PNVCL onto TPU films using gamma radiation.

Clinical and functional characterization of rare compound heterozygous mutations in the SERPINC1 gene causing severe thrombophilia

IntroductionHereditary antithrombin (AT) deficiency is a rare autosomal dominant disorder with significant clinical heterogeneity. In the study, we identified a patient with AT deficiency caused by compound heterozygous mutations in the SERPINC1 gene. MethodsA total of 9 individuals from three generations were investigated. The mutations were identified by direct sequencing of SERPINC1. Multiple in silico tools were programmed to predict the conservation of mutations and the effect on the AT structure. The coagulation state was evaluated by the thrombin generation assay. Recombinant AT was overexpressed in HEK293T cells; the mRNA level was determined using RT-qPCR. Western blotting, ELISA, and immunocytofluorescence were applied to characterize the recombinant AT protein. ResultsThe proband was a 26-year-old male who experienced recurrent venous thrombosis. He presented the type I deficiency with 33 % AT activity and a synchronized decrease in AT antigen. Genetic screening revealed that he carried a heterozygous c.318_319insT (p.Asn107*) in exon 2 and a heterozygous c.922G > T (p.Gly308Cys) in exon 5, both of which were completely conserved in homologous species and resulted in enhanced thrombin generation capability. Hydrophobicity analysis suggested that the p.Gly308Cys mutation may interfere with the hydrophobic state of residues 307–313. In vitro expression studies indicated that the levels of the recombinant protein AT-G308C decreased to 46.98 % ± 2.94 % and 41.35 % ± 1.48 % in transfected cell lysates and media, respectively. After treatment with a proteasome inhibitor (MG132), the quantity of AT-G308C protein in the cytoplasm was replenished to a level comparable to that of the wild type. The mRNA level of AT-N107* was significantly reduced and the recombinant protein AT-N107* was not detected in either the lysate or the culture media. ConclusionThese two mutations were responsible for the AT defects and clinical phenotypes of the proband. The p.Gly308Cys mutation could lead to proteasome-dependent degradation of the AT protein in the cytoplasm by altering local residue hydrophobicity. The c.318_319insT could eliminate aberrant transcripts by triggering nonsense-mediated mRNA degradation. Both mutations resulted in type I AT deficiency.

Interaction and Inhibition Mechanism of Sulfuric Acid with Fluorapatite (001) Surface and Dolomite (104) Surface: Flotation Experiments and Molecular Dynamics Simulations

The natural wettability of apatite and dolomite and the effect of sulfuric acid (H2SO4) and sodium oleate (NaOl) on the floatability and wettability of both minerals were studied using single-mineral flotation and contact angle measurement. The flotation experiments demonstrated that adding NaOl, apatite, and dolomite had good floatability. After adding H2SO4, the floatability of apatite decreased significantly. H2SO4 effectively inhibits apatite flotation. Contact angle measurements show that the use of H2SO4 induces a significant difference in surface wettability between apatite and dolomite. The moderate addition of H2SO4 can increase the contact angle of dolomite. In order to study the selective inhibition mechanism of H2SO4 in phosphorite flotation, molecular dynamics simulations (MDSs) were conducted to investigate the interaction between H2SO4 and fluorapatite and dolomite at the atomic–molecular level. The results of MDSs reveal that H2SO4 interacts with Ca sites on both fluorapatite and defective dolomite surfaces, hindering the interaction of NaOl with Ca sites on both mineral surfaces. SO42− ions cannot prevent the interaction of oleate ions with Mg sites on dolomite surface. It is worth mentioning that SO42− ions occupy the defective vacancies formed due to the dissolution of CO32− on the surface of dolomite and interact with Ca sites. The remaining H2SO4 is subsequently adsorbed onto the surface of dolomite. Experimental and simulation results show that, due to the interaction of H2SO4 and NaOl, the surface of apatite can still undergo hydration forming a water molecule layer and maintaining a macroscopic hydrophilic property. In contrast, the oleate ions form an adsorption layer on dolomite transitioning it from a hydrophilic to a hydrophobic state. During the phosphate flotation process, the addition of an appropriate amount of sulfuric acid can further diminish the hydration of the dolomite surface, so that the surface of dolomite is more hydrophobic.

Near-infrared femtosecond laser direct writing of microchannel and controlled surface wettability

The application of femtosecond laser in fabricatingpoly (methyl methacrylate) microchannels and the alteration of wettability by inducing a change in chemical functional groups has already been established and reported in literature.However, studies on the application of femtosecond laser for modification of surface wettability without significant chemical modification,are yet to be reported. The paper reports work on an expedition of femtosecond (Ytterbium-doped fiber) laser ablation working at the near-infrared wavelength (1030 nm) tuning the wettability behavior comprising of hydrophilic and hydrophobic state on the basis of the surface morphology created below the focal beam diameter. The initial part revolves around the investigation of near-infrared femtosecond laser ablation for achieving microcavity and microchannel below the focal beam diameter. The latter part deals with laser surface modification for attaining both hydrophilic and hydrophobic surfaces. The study obtained a high degree of hydrophobicity, with a maximum water contact angle of 129.05°at a laser energy of 40 μJ and pulse laser overlap of 96%. It was also possible to attain a minimum water contact angle of 56.35°using a laser pulse energy of 40 μJ and pulse overlap of 0 %. The reported work avoids surface chemical modification for controlling the wettability.

Electron-Beam Processing of Aluminum-Containing Ceramics in the Forevacuum Pressure Range

Aluminum–ceramic materials based on Al2O3 and AlN are widely used in the electronics industry and, according to a number of electrophysical and technical and economic parameters, are among the most suitable for the production of electrical and radio engineering products. In this study, it is shown that the treatment of ceramics based on Al2O3 with an electron beam with a power of 200–1100 W and a current of 10–50 mA leads to heating of the ceramic surface to a temperature of 1700 °C. When heated to a temperature of 1500 °C and kept at this temperature for no more than 10 s, an increase in the roughness of the ceramic surface is observed by more than an order of magnitude. At the same time, for ceramic substrates based on aluminum nitride, an increase in the temperature of electron beam treatment from 1300 to 1700 °C leads to an increase in thermal conductivity from 1.5 to 2 times. The edge angle of water wetting of the AlN surface can vary from 20 to 100 degrees depending on the processing temperature, which allows one to control the transition of the material from a hydrophilic to a hydrophobic state. At the same time, electron beam exposure to Al2O3 does not change the wettability of this material so much. Electron beam processing in the forevacuum pressure region allows controlled changes in the electrophysical properties of ceramic materials based on Al2O3 and AlN.

Physical feature exploration of nanocrystalline FeSi2 surface with argon plasma etching under varying power

Nanocrystalline (NC) FeSi2 films were created on Si(111) wafers via direct-current sputtering with facing targets at an ambient temperature, then the films were etched by Ar plasma generated through microwave source at different powers of 50, 100, and 150 W. The surface morphology of the as-coated NC FeSi2 films showed numerous small uniform crystallites and root-mean-square roughness of 4.65 Å. The surface for each etched NC FeSi2 film showed appearance of holes and slight increase in the roughness as the power increased. X-ray photoelectron spectra showed that the etching decreased the content of hydrophobic carbon and increased the presence of polar oxide group on the NC FeSi2 films as the power increased. These changes should be the factor behind the shift from hydrophobic state to hydrophilic state. The contact angle of the unetched NC FeSi2 film surface was 100.55°, which is hydrophobic. The NC FeSi2 film's surface reached a minimum contact angle of 35.65°, which belong to hydrophilic state, when the etching power was increased to 150 W. The mechanical properties of NC FeSi2 films rarely affect by Ar plasma. The change in surface state to nearly superhydrophilic after plasma etching indicate possibility to develop NC FeSi2 into a self-cleaning surface coating material.

Photoresponsive Electrospun Fiber Meshes with Switchable Wettability for Effective Fog Water Harvesting in Variable Humidity Conditions.

The global water supply worsens yearly with climate change; therefore, the need for sustainable water resources is growing. One of them is fog water collectors with variable surface wettability, with multifunctional designs for utilization worldwide and to address regions with low humidity levels. Therefore, we created fiber meshes with a photoresponsive switchable surface. This study uses electrospun polyvinylidene fluoride (PVDF) meshes, whose wettability is controlled by adding TiO2. The fog water collection performance is studied at high and low humidity levels. With TiO2-PVDF, the electrospun mesh can be converted from hydrophobic to hydrophilic under UV irradiation and transformed back to a hydrophobic state with heat treatment. The switchable meshes were found to be more effective at water collection after UV irradiation at lower fog rates of 200 mL·h-1. The ability to switch between hydrophobic and hydrophilic properties as needed is highly desired in fog collection applications using electrospun meshes, as it can improve overall efficiency after UV irradiation.

Fabrication and testing of a multifunctional SiO2@ZnO core–shell nanospheres incorporated polymer coating for sustainable marine transport

We report the development of a coating system relying on the incorporation of SiO2@ZnO core–shell nanospheres in polyurethane media as a novel approach to achieve longevity and sustainability in marine transport. This polymeric coating showed significant improvement in surface abrasion resistance, the transition from a hydrophilic state to a hydrophobic state (~ 125.2° ± 2°), improved antifungal, antibacterial and antialgae effects which make the proposed coating ideal to protect steel surfaces against biofouling. To substantiate our claims, we performed X-ray diffraction, Transmission electron microscopy, Fourier transform infrared spectroscopy, scanning acoustic microscopy, Thermogravimetric analysis (TGA), contact angle measurements, antimicrobial (antialgal, antibacterial, antifungal) tests and Taber abrasion tests (ASTM D1044 and D4060) to highlight the mechanical and biological functionality as well as the bonding configuration of this coating. The wear analysis of the Taber abraded coating using SEM and optical microscopy showed significant improvement in the adhesion and shear resistance achieved by the SiO2@ZnO core–shell nanospheres incorporated PU coating which was a contrasting feature compared to using PU alone. The overall investigations we performed led us to find out that the addition of 4% (wt.) SiO2@ZnO core–shell nanoparticles to the PU media deposited on the low carbon steel surface demonstrated remarkable antimicrobial performance with almost no bacterial growth, significant reductions in growth for algae to about 90% and fungus to about 95%.

Evaluating hydrophobic recovery of N2 and H2O(g) plasma modified silk fibroin films aged at ambient and elevated temperatures.

Silk fibroin is a naturally derived polymer with great potential for biomedical use due to its strength, lack of immune response, and ability to biodegrade. The relatively hydrophobic nature of silk, however, can cause challenges with cell adhesion in vivo. Therefore, modification must be performed to improve the surface hydrophilicity, enhancing silk utility in the biomedical space. Low-temperature plasma (LTP) treatment is an established method for polymer modification and has the benefits of being a solvent-free, adaptable process. N2 and H2O(g) LTP treatments are both well-documented as strategies to enhance polar functional groups on a polymer's surface. However, many polymers tend to revert to their original hydrophobic state upon aging, reversing the effects of LTP modification. The hydrophobic recovery of N2 and H2O(g) LTP-modified silk has not been previously studied but has important implications for the uses and longevity of silk substrates in biomedical contexts. The goal of this study was to systematically evaluate the hydrophobic recovery of N2 and H2O(g) LTP-treated silk films. Films were LTP-modified using optimized plasma parameters (applied power, pressure, treatment time) and aged under both ambient and elevated temperature conditions up to 6 weeks after the initial treatment. Silk film surface properties were evaluated immediately after treatment and throughout the aging process using both water contact angle goniometry and x-ray photoelectron spectroscopy. LTP-treated silk films demonstrated a significant decrease in hydrophobicity compared to the untreated controls. Remarkably, both N2 and H2O(g) LTP modifications resulted in surfaces that retained hydrophilic properties over the 6 week aging period. Our findings represent a departure from what has been previously demonstrated in most LTP-modified synthetic polymers, suggesting that the secondary structure of silk fibroin plays a critical role in resisting hydrophobic recovery.

An effervescence-assisted switchable deep eutectic solvent based liquid-phase microextraction of triazole fungicides in drinking water and beverage

A new effervescence-assisted switchable deep eutectic solvent-based liquid phase microextraction (EA-SDES-LPME) combined with HPLC-UV was developed for determination of common triazole fungicides in drinking water and beverages, including myclobutanil, flusilazole, hexaconazole and bitertanol. The alternative extraction solvent was prepared with hexafluoroisopropanol and dipropylamine with the merits of time-saving, easy to collect and cost-effectiveness. The SDES can be reversibly switched between hydrophilic and hydrophobic states by pH adjustment. The homogeneous extraction was achieved under the hydrophilic form of SDES, and the bi-phase separation was obtained easily by adjusting pH value to restore the original hydrophobicity. Moreover, the characterization of SDES was investigated by FTIR and 1H NMR. The main variables affecting extraction efficiency were optimized in detail. Under the optimal conditions, the proposed method shows desirable precision (RSDs less than 18.5%) and acceptable recovery (72.6–95.4%). The lower limits of detection and limits of quantitation were found to be in the range of 1–2 μg L-1 and 5–10 μg L-1, respectively. The formation mechanism of SDES and the extraction mechanism for target analytes were investigated by density functional theory. The proposed methodology was simplicity, sensitive, time-saving and successfully applied to determine triazole fungicides in drinking water and beverages, making it an alternative technique for the analysis of trace analytes with satisfactory sensitivity.

Hydrogen-wettability alteration of Indiana limestone in the presence of organic acids and nanofluid

This study focuses on the wettability alteration (changing from a hydrophobic state to a hydrophilic state) of Indiana limestone for hydrogen (H2) geological storage. We examine the effect of hexanoic acid C6, lauric acid C12, and stearic acid C18, on the wettability of Indiana limestone at ambient (298 K and 0.1 MPa) and reservoir (323 K and 8.27 MPa) conditions. The effects of silica nanofluids (silica with deionized water) at various concentrations (0.1 wt%, 0.25 wt%, and 0.5 wt%) on the wettability reversal of stearic-aged samples were tested at ambient and reservoir conditions. The results revealed increased H2-wetness (hydrophobicity) of the rock exposed to these organic acids in reservoir conditions. However, this hydrophobicity significantly decreased with the nanofluid treatment of the stearic-aged samples. This wettability reversal may increase the H2 storage capacity and containment security and lead to successful large-scale geological storage operations if H2 residual trapping is minimized.

Regulation of three-dimensional hydrophobic state of copper dendrite adjusts the distribution of liquid products from electrochemical reduction of CO2

Cu is the most common catalyst for CO2 reduction reaction (CO2RR). Here, we propose a strategy for the design of the wetting state of the catalyst under water to obtain a local environment in which reactants and intermediates are enriched to improve the selectivity of the target product. The addition of 3% polytetrafluoroethylene (PTFE) coating can make the catalyst have the stable triphase interface required for CO2RR without destroying the dendrite structure, thus achieving a twofold enhancement of the intrinsic activity of the active site. Dendrites with low-concentration PTFE coating will soon lose hydrophobic ability after applying potential, while high-concentration PTFE coating will cause dendrite collapse and lose the ability to trap gas between dendrites. The Faradaic efficiency (FE) ratio of methanol (CH3OH) to formic acid (HCOOH) of the hydrophobic electrode is threefold higher than untreated electrode at medium potential, and the FE of ethanol (C2H5OH) increased by twofold at higher potential. These are assigned to the rapid enrichment and diffusion of gas on the surface of the hydrophobic electrode. This work has provided a basis for the design of novel 3D hydrophobic catalysts and may lead to a complete understanding of the mechanism of CO2RR.

Hierarchical structured surfaces enhance the contact angle of the hydrophobic (meta-stable) state.

The relation between wetting properties and geometric parameters of fractal surfaces are widely discussed on the literature and, however, there are still divergences on this topic. Here we propose a simple theoretical model to describe the wetting properties of a droplet of water placed on a hierarchical structured surface and test the predictions of the model and the dependence of the droplet wetting state on the initial conditions using simulation of the 3-spin Potts model. We show that increasing the auto-similarity level of the hierarchy - called n - does not affect considerably the stable wetting state of the droplet but increases its contact angle. Simulations also explicit the existence of metastable states on this type of surfaces and shows that, when n increases, the metastability becomes more pronounced. Finally we show that the fractal dimension of the surface is not a good predictor of the contact angle of the droplet.

Aliquots of MIL-140 and Graphene in Smart PNIPAM Mixed Hydrogels: A Nanoenvironment for a More Eco-Friendly Treatment of NaCl and Humic Acid Mixtures by Membrane Distillation.

The problem of water scarcity is already serious and risks becoming dramatic in terms of human health as well as environmental safety. Recovery of freshwater by means of eco-friendly technologies is an urgent matter. Membrane distillation (MD) is an accredited green operation for water purification, but a viable and sustainable solution to the problem needs to be concerned with every step of the process, including managed amounts of materials, membrane fabrication procedures, and cleaning practices. Once it is established that MD technology is sustainable, a good strategy would also be concerned with the choice of managing low amounts of functional materials for membrane manufacturing. These materials are to be rearranged in interfaces so as to generate nanoenvironments wherein local events, conceived to be crucial for the success and sustainability of the separation, can take place without endangering the ecosystem. In this work, discrete and random supramolecular complexes based on smart poly(N-isopropyl acrylamide) (PNIPAM) mixed hydrogels with aliquots of ZrO(O2C-C10H6-CO2) (MIL-140) and graphene have been produced on a polyvinylidene fluoride (PVDF) sublayer and have been proven to enhance the performance of PVDF membranes for MD operations. Two-dimensional materials have been adhered to the membrane surface through combined wet solvent (WS) and layer-by-layer (LbL) spray deposition without requiring further subnanometer-scale size adjustment. The creation of a dual responsive nanoenvironment has enabled the cooperative events needed for water purification. According to the MD's rules, a permanent hydrophobic state of the hydrogels together with a great ability of 2D materials to assist water vapor diffusion through the membranes has been targeted. The chance to switch the density of charge at the membrane-aqueous solution interface has further allowed for the choice of greener and more efficient self-cleaning procedures with a full recovery of the permeation properties of the engineered membranes. The experimental evidence of this work confirms the suitability of the proposed approach to obtain distinct effects on a future production of reusable water from hypersaline streams under somewhat soft working conditions and in full respect to environmental sustainability.

Preparation of liquid-infused surface on epoxy resin for improved tribological and anti-corrosion performance

Epoxy resin (ER) is widely used in the coating industry, but some of its characteristics such as hydrophilicity limit the tribological and anti-corrosion performance. Liquid-infused surfaces (LIS) have the potential to improve surface properties and solve numerous industrial issues. In this study, LIS was prepared on ER by constructing surface texture, modifying treatment, and injecting lubricant. The relationship between the texture density of the textured substrate and the wetting, tribological, and anti-corrosion performance of the LIS was investigated. The results showed that the preparation of LIS transformed the ER from a hydrophilic to a hydrophobic state, reducing the sliding angle of water droplets on the coating surface. The texture density of the textured substrate influenced the wetting performance of LIS by affecting the height of the oil film. The LIS with a high-density textured substrate exhibited excellent tribological and anti-corrosion performance due to its lubrication ability, barrier effect, and low surface energy characteristic of the oil film. This report provides valuable information for the design of LIS, and the prepared coating has promising applications in the field of high-performance protective coatings.

Photo‐ and pH‐Responsive Hybrid Colloidal Particles

AbstractMaterials that respond to environmental changes in a predictable manner are called “smart”. Here, smart dual‐responsive hybrid colloidal particles were prepared using the interface‐mediated reversible addition–fragmentation chain‐transfer (RAFT) polymerization method. The structure and morphology of the prepared poly(methacrylated‐spiropyran) (p(MMASP)) colloids were characterized by FTIR, 1H‐NMR and GPC spectroscopies, and SEM. The molecular weight and polydispersity were determined as 7877 g mol−1 and 1.16, respectively. Heterocyclic ring cleavage of the spiropyran (SP) pendant group enables the pH‐ and light‐responsive behavior with a reversible conversion between the hydrophobic and hydrophilic states. The isomerization from SP to merocyanine (MC) form proceeds in 7 min, while the reverse action takes 9 min. The pronounced photochromic effect and high fatigue resistance make these colloids suitable for smart applications.

Rational design of dopamine-decorated gradient structure membrane with novel hydrophibic/underwater-oleophobic for oil/water separation

The shortage of water resources and the aggravation of water pollution have become global environmental problems. The improvement of the separation performance and flux is still a key challenge that restrict the preparation of high-performance filtration membrane. The gradient structure fibrous membranes were designed and prepared using electrospinning nanofiber and polypropylene/low-melt- point polyester (PP/LPET) micro-fibrous and reinforced via needle-punching and hot-pressing. And the as-prepared membrane was functionalized and directly decorated by dopamine copolymerizes. The novel gradient membrane turned from a hydrophobic state to hydrophilic state, and had excellent mechanical and water transmission properties. Mostly importantly, the as-prepared hydrophilic gradient membranes showed durable oil-fouling repellency and the separation efficiency of oil/water mixture approximate 99% and the flux reach 10,278 ± 1512 L m−2 h−1. This method provides a feasible solution to overcome the high filtration resistance of electrospinning nanofiber membrane, as well as for the preparation of low-cost and high-performance composite membranes and structural regulation of functional membranes.