Thiol-ene Click Reaction Research Articles

A facile preparation method of UV rapid curing fluorosilicone coatings with good hydrophobicity and excellent corrosion resistance based on thiol-ene click reaction

As reported herein, UV rapid curing fluorosilicone coatings with good hydrophobicity and corrosion resistance were developed with a novel fluorosilicone polymer possessing thiol functional groups (PTFPMS-SH) and a series of fluorosilicone polymers having different vinyl content (PTFPMS-Vi). The chemical structures of the prepared polymers (PTFPMS-Vi and PTFPMS-SH) were first characterized by FT-IR (fourier infrared transform spectroscopy) and 1H NMR (nuclear magnetic resonance), confirming the successful synthesis of expected polymers. Subsequently, the curing process, basic properties, thermal properties and surface properties of the UV cured fluorosilicone coatings were investigated. Moreover, the application of the fluorosilicone coatings as anti-corrosion coatings in the field of circuit boards were also preliminarily explored. The results show that the photocuring reaction based on the thiol-ene reaction for the preparation of fluorosilicone coatings is very effective because the conversion rate of carbon‐carbon double bonds can reach more than 95 % within 5 s under UV irradiation. These obtained fluorosilicone coatings exhibit transparency higher than 90 %. The contact angle of the obtained coatings ranges from 100° to 110°, showing their excellent hydrophobicity. Furthermore, the fluorosilicone coatings with outstanding corrosion resistance show their potential application worth as protective coatings for electronic devices.

Ultra-large dynamic range synaptic indium gallium zinc oxide transistors

Three-terminal neuromorphic transistors have garnered considerable attention owing to their superior learning and recognition capabilities in neural computing. For efficient and rapid computing of parallel arithmetic and unstructured large-sized data, a high-synaptic channel conductance (G) (i.e., synaptic weight) and large dynamic range (DR) (i.e., weight update) are necessary. In this study, we successfully fabricated high-performance and all-solution-processed synaptic transistors by employing a thiol–ene photoclick chemistry-based, cross-linked vinyl addition polynorbornene copolymer dielectric layer, poly(norbornene-co-5-vinyl-2-norbornene) (P(NB/VNB)) and sol-gel-derived indium gallium zinc oxide (IGZO) semiconducting channel layer. The molecular behaviors of free hydroxyl group in the dielectric layer formed via ultraviolet photo-induced thiol–ene click reactions of the polar cross-linker pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) allows slow dipole polarization effects on the IGZO channel layer. An exhaustive and systemic investigation of the surface physicochemical and electrical properties confirmed that the mutual interface coupling between the cross-linked P(NB/VNB) dielectric and IGZO semiconductor exhibited remarkable synaptic functionality with a high G (∼540 μS), large DR (∼6213), and long-term operational stability following excitation with 104 successive pulses that resulted in neural recognition accuracy of 87.11% based on the use of MNIST database set which is close to ideal value of 88%. This high-performance synaptic transistor based on all-solution-derived functional organic–inorganic hybrid stack layers can serve as a basis for the successful implementation of novel neuromorphic computing systems that satisfy the requirements for strong neuronal signal transmission and distinguishable multi-level data states.

Robust and Highly Transparent Photocurable Fluorinated Polyurethane Coating Prepared via Thiol-Click Reactions and What Essentially Influences Omniphobic Coating’s Anti-Graffiti Properties

Without a fragile micro/nanostructure, omniphobic coatings have a natural advantage over superomniphobic coatings in mechanical durability, especially when confronted with finger wipes and squeezes in practical use. Many reported omniphobic coatings with lower liquid sliding angles showed better ink trace resistance. However, according to our results, these two properties are not positively related. The respective critical factors for lowering the liquid sliding angle and resisting tiny contaminants, such as ink stroke and fingerprint, remain elusive. Through three steps of the thiol-click reaction, a surface-dried, highly transparent, mechanically and chemically robust, fluorinated polyurethane coating was photocured efficiently. Surfaces that exhibited better sliding performance but worse resistance to ink stroke and fingerprint were reported. Our results indicate that a heavy cross-linked structure was beneficial for the resistance to tiny contaminants, while the liquid sliding performance only depended on the surface fluorine content, especially the surface enrichment of flexible low-surface-tension chains. Interestingly, an unexpected transformation from a turbid dispersion to a transparent solution during the preparation was observed. The efficient thiol-click reaction induces a micelle-like structure to open and imparts high transparency to the final coatings. Therefore, this work provides useful information to facilitate the study of omniphobic coatings, as well as a good candidate in anti-graffiti applications.

Click chemistry functionalization of self-assembling peptide hydrogels.

Self-assembling peptide (SAP) hydrogels provide a fibrous microenvironment to cells while also giving users control of biochemical and mechanical cues. Previously, biochemical cues were introduced by physically mixing them with SAPs prior to hydrogel assembly, or by incorporating them into the SAP sequence during peptide synthesis, which limited flexibility and increased costs. To circumvent these limitations, we developed "Click SAPs," a novel formulation that can be easily functionalized via click chemistry thiol-ene reaction. Due to its high cytocompatibility, the thiol-ene click reaction is currently used to crosslink and functionalize other types of polymeric hydrogels. In this study, we developed a click chemistry compatible SAP platform by addition of a modified lysine (lysine-alloc) to the SAP sequence, enabling effective coupling of thiol-containing molecules to the SAP hydrogel network. We demonstrate the flexibility of this approach by incorporating a fluorescent dye, a cellular adhesion peptide, and a matrix metalloproteinase-sensitive biosensor using the thiol-ene reaction in 3D Click SAPs. Using atomic force microscopy, we demonstrate that Click SAPs retain the ability to self-assemble into fibers, similar to previous systems. Additionally, a range of physiologically relevant stiffnesses can be achieved by adjusting SAP concentration. Encapsulated cells maintain high viability in Click SAPs and can interact with adhesion peptides and a matrix metalloproteinase biosensor, demonstrating that incorporated molecules retain their biological activity. The Click SAP platform supports easier functionalization with a wider array of bioactive molecules and enables new investigations with temporal and spatial control of the cellular microenvironment.

“Click” preparation of a chiral macrocycle-based stationary phase for both normal-phase and reversed-phase high performance liquid chromatography enantioseparation

Chiral polyimine macrocycles (CPMs) constitute a new family of organic macrocycles that have defined cavities, rigid shapes, inherent chirality and multiple cooperative binding sites, and have shown great potential in diverse areas. However, the application of CPMs for high performance liquid chromatography (HPLC) enantioseparation has rarely been reported. In this work, a novel chiral stationary phase (CSP) for HPLC was prepared by chemical bonding of a CPM (C54H72N6O3) onto thiolated silica via thiol-ene click reaction. The CSP exhibited good enantioselectivity in both normal- and reversed-phase HPLC. Chiral compounds included alcohols, diols, ketones, organic acids, esters, ethers, amines, and epoxides were enantioseparated on the column in normal-phase mode (17 compounds) and reversed-phase mode (20 compounds). Importantly, broader chiral resolution was observed with the column than that obtained using our previously studied chiral macrocycle H3L-based column, indicating the potential to significantly improve and broaden applicability of this novel macrocycle-type CSPs. Moreover, the CSP exhibited good complementary enantioseparation to Chiralpak AD-H and Chiralcel OD-H columns, enabling separation of some racemates that could not be separated by the two popular chiral HPLC columns. In addition, the fabricated column exhibited good stability and reproducibility. The relative standard deviations (RSDs) (n = 5) of retention time and resolution after multiple injections were < 0.20 % and < 0.39 %, respectively. The results demonstrated the great potential of this type of CPM for HPLC separation of enantiomers.

Preparation of thioglycerol-modified silica through thiol-epoxy click reaction and its application in HILIC for detection of oligosaccharide in beverages

A novel preparation scheme of thioglycerol-modified silica through thiol-epoxy click reaction was proposed aiming at introducing additional quantities of hydroxyl groups into the structure. When applied as the stationary phase of hydrophilic interaction liquid chromatography (HILIC) for separation of oligosaccharide compounds, the material revealed higher polar separation capability than which synthesized through traditional thiol-ene click reaction. Hydrogen-bond interactions were speculated to be the predominant retention mechanism, while partitioning also participated in the retention of disaccharides and trisaccharides. The column also showed good stability and inter-batch reproducibility. Finally, the column was employed for determination of oligosaccharide compounds in commercial beverages, and good linearities, high accuracy, favorable precision, satisfactory reproducibility and resistance to matrix interference were achieved. In the detection of real samples, the determined content was consistent with the labeled content. This work provided an efficient and practicable method for quantity monitoring of commercial diet drinks in routine laboratory.

Activated polyallene as versatile substrate for efficient preparation of fluorinated composite

Introduction of fluorine into composites has been a subject of intense research because it brings about significant improvements in the performance of the composites. In particular, fluorine-containing composites exhibit excellent thermal stability, good chemical stability and low surface energy. However, the design of fluorine-containing composites is limited by the current polymerization and modification techniques. Herein, a series of double-bond-containing poly(phenoxyallene) (PPOA) polymers with tunable structure were facilely prepared through reversible addition-fragmentation chain transfer (RAFT) polymerization. To identify the RAFT polymerization conditions, RAFT homopolymerization of phenoxyallene (POA) was firstly conducted as a typical reaction. The effects of chain transfer agent (CTA), substituent of POA, temperature, and solvent were systematically investigated. Notably, highly efficient thiol-ene click reaction can be used for the direct modification of PPOA without further polymeric functionality transformation. When fluorinated thiol was used as reactant, a functional fluorine-containing polymer could be simply achieved, demonstrating the highly efficient efficiency of the postpolymerization modification. Considering the simple RAFT polymerization condition and excellent reactivity of double bonds in polymer structure, this thiol-ene postpolymerization modification might be a versatile platform for the precise fabrication of a broad variety of functional composites, especially for fluorine-containing composites.

A New Photoelectrocatalyst for Water Oxidation: A Polyoxometalate-Graphitic Carbon Nitride Hybrid Nanomaterial.

A new photoelectrocatalyst for the water oxidation process is designed by immobilizing [CoW12O40]6- (CoW12) heteropolyanions on the surface of covalently modified graphitic carbon nitride nanosheets (g-C3N4). For this purpose, g-C3N4 is first modified with cysteamine hydrochloride through the well-known thiol-ene click reaction. Afterward, [CoW12O40]6- heteropolyanions are immobilized on the surface of modified g-C3N4 nanosheets with electrostatic interaction with ammonium groups. After confirming the preparation of CoW12/clicked g-C3N4 with various physicochemical methods, its photoelectrocatalytic activity is evaluated in the oxygen evolution reaction. The CoW12/clicked g-C3N4 exhibits a low onset potential of 1.32 V versus NHE and a low overpotential of 230 mV at 10 mA cm-2 with a low Tafel slope of 67 mV dec-1 under visible light illumination. Moreover, the stability of the catalyst is investigated through the chronoamperometric measurements.

Superhydrophobic PDMS@GSH wood with Joule heat and photothermal effect for viscous crude oil removal

Recently, the membrane separation materials show promising applications in the fields of crude oil removal because of their low energy consumption and less secondary pollution. However, the membrane separation materials suffer problem of low separation efficiency due to the high viscosity of crude oil. Here, a superhydrophobic material with Joule heat and photothermal effect was prepared by decorating the delignified wood with reduced graphene oxide (GSH) and vinyl terminated polydimethylsiloxane (V-PDMS) through thiol-ene click reaction. The prepared PDMS@GSH wood exhibited stable superhydrophobicity with a water contact angle of 156°. Meanwhile, the GSH layer provided promising electrothermal effect that endowed the PDMS@GSH wood with excellent crude oil/water separation capability under the Joule heat with a surface temperature of 139 °C and separation rate of 1.78 × 105 kg m−3 h−1. Besides, the PDMS@GSH wood displayed a good photothermal effect that assisted with the Joule heat to heat the wood for crude oil removal to save energy. More importantly, the PDMS was crosslinked with GSH on the wood via thiol-ene click reaction, leading to the stable superhydrophobicity and electrical conductivity in strong acid or alkali environment. This material has broad application prospects in crude oil clean-up due to its high separation speed and easy large-scale production.

The design and preparation of high-performance ABS-based dielectric composites via introducing core-shell polar polymers@BaTiO3 nanoparticles

In consideration of inherent high hysteretic losses resulting in low energy efficiency for ferroelectric polymer, linear dielectric acrylonitrile butadiene styrene (ABS) with low price and good film property is adopted as optimal polymer matrix. Synchronously, representative ferroelectric barium titanate (BT) nanoparticles with high dielectric constant are selected as the nanofiller. To weaken the surface energy of BT nanoparticles and boost the interfacial interaction, polar polymer (poly[bis(4-cyanophenyl) 2-vinylterephthalate] (PBCN)) is employed as organic coatings to regulate interfacial property. Consequently, core–shell structured PBCN@BT nanoparticles were synthesized by means of reversible addition-fragmentation chain transfer polymerization combined with thiol-ene click reaction and the corresponding ABS-based nanocomposites were prepared. In consequence, discharge energy density increased from 3.2 J/cm3 for the pure ABS film to 4.5 J/cm3 for the 0.5 vol%-PBCN@BT/ABS nanocomposites. Meantime, a high energy efficiency of 76% was found. This discovery is of great significance for the development of excellent performance ABS-based dielectric composites.

Construction of Degradable and Amphiphilic Triblock Polymer Carriers for Effective Delivery of siRNA.

The development of effective and safe delivery carriers is one of the prerequisites for the clinical translation of siRNA-based therapeutics. In this study, a library of 144 functional triblock polymers using ring-opening polymerization (ROP) and thiol-ene click reaction is constructed. These triblock polymers are composed of hydrophilic poly (ethylene oxide) (PEO), hydrophobic poly (ε-caprolactone) (PCL), and cationic amine blocks. Three effective carriers are discovered by high-throughput screening of these polymers for siRNA delivery to HeLa-Luc cells. In vitro evaluation shows that siLuc-loaded nanoparticles (NPs) fabricated with leading polymer carriers exhibit sufficient knockdown of luciferase genes and relatively low cytotoxicity. The chemical structure of polymers significantly affects the physicochemical properties of the resulting siRNA-loaded NPs, which leads to different cellular uptake of NPs and endosomal escape of loaded siRNA and thus the overall in vitro siRNA delivery efficacy. After systemic administration to mice with xenograft tumors, siRNA NPs based on P2-4.5A8 are substantially accumulated at tumor sites, suggesting that PEO and PCL blocks are beneficial for improving blood circulation and biodistribution of siRNA NPs. This functional triblock polymer platform may have great potential in the development of siRNA-based therapies for the treatment of cancers.

Synthesis of high-toughness waterborne polyurethane utilizing self-emulsifying CO2-based polyols

In this work, a self-emulsifying CO2-based polyol (LAPEC) was prepared by the terpolymerization of propylene oxide, allyl glycidyl ether and CO2, followed by thiol-ene click reaction with mercaptopropionic acid. And the carboxyl group was successfully introduced into LAPEC verified in 1H NMR. LAPEC was served as both soft segments and internal emulsifiers for WPU. Meanwhile, γ-aminopropylmethyldiethoxysilane (KH902) was also employed to improve the mechanical properties of WPU. Compared to dimethylol propionic acid (DMPA), WPU emulsion prepared by LAPEC had smaller particle size and higher emulsification efficiency. And the performance differences between LAPEC-based WPU films (LWPUs) and DMPA-based WPU films (DWPUs) with different hard segment contents were studied. The stronger hydrogen-bonding interactions improved the tensile strength, toughness and thermal stability. Compared with DWPU, the tensile strength and the elongation at break of LWPU respectively increased from 17.8 to 21.1 MPa and from 302.3 % to 356.5 %, when their hard segment content was both maintained around 37 wt%. Meanwhile, due to rougher surfaces and more hydrophobic silicon clusters, LWPU had stronger surface hydrophobicity. Therefore, LAPEC can provide a new way to synthesize WPU with high toughness and can be potentially used for flexible substrate coatings in the future.

Gemini ionic liquid modified nacre-like reduced graphene oxide click membranes for ReO4−/TcO4− removal

99Technetium (99Tc), as a kind of dangerous radioactive isotopes, captured from groundwater is an extremely urgent problem. A functionalize graphene oxide flexible membrane (GO-C6) was successfully obtained using thiol-ene click reaction, where CC bond of graphene network can further to connect to the gemini ionic liquids. The click membranes modified by Gemini C4 IL, Gemini Ph IL or Gemini C6 IL exhibited different adsorption capacity for ReO4− /TcO4−, where it enhanced with the increase of number of the alkyl chains C1, C4, C6 in the corresponding structure of GO-Ph, GO-C4, GO-C6. The maximum adsorption capacity of GO-C6 at pH 3, pH 4, pH 6 and pH 10 was evaluated as 269.17 mg g−1, 246.36 mg g−1, 252.55 mg g−1, and 238.67 mg g−1, respectively. In addition, the stable removal efficiency was verified through regenerative and selective experiment in the presence of competing anions, including Cl−, SO42−, NO3–, and PO43− in certain nuclear waste. The ion exchange reaction between ReO4− /TcO4− and Cl− on the imidazolium modified GO membranes played dominant role in the adsorption mechanism. In short, reduced graphene oxide click membranes modified by gemini ionic liquid showed good application prospects in removal of radioactive 99Tc.

Preparation and performance of nitrogen–phosphorus–silicone-containing flame retardant UV–curable coatings with high transparency

UV-curable transparent silicone-modified flame retardant materials are highly desired because they usually serve as protecting polymer matrix from moisture, ionic contaminants and particulates in vast fields such as coatings, electronic devices attributed to their merits such as high flame-retardant efficiency, high curing efficiency and low volatile organic chemical emissions. In this paper, nitrogen–phosphorus–silicone-containing flame retardant UV-curable coatings were prepared from nitrogen–phosphorus–silicone-containing acrylate and thiol-containing silicone hyperbranched polymers by UV initiated thiol-ene click reaction. It shows that these coatings were with fairly high transmittance, pencil hardness and initial decomposition temperature (Td5) of 80.7–96.9 % (400–800 nm), 9H, and 159–185 °C, respectively. Vertical burning behavior of the UV-curable coatings prepared with different acrylate derivatives was investigated and the self-extinguish time for the coatings prepared from POPHA was about 9 s. To make clear of the flame retardant mechanism, cone calorimetric test and XPS spectra of UV-curable coatings, and SEM images for the surface morphology of the chars were carried out. SEM images of the chars show that there is fine and dense white SiO2 “in-situ” generated during the course of combustion spreading on the surface. It also shows that honeycombed-like structures attributed by nitrogen and phosphorus form a quite good barrier to heat, oxygen and other flammable gas. Therefore, a ternary synergistic flame retardant mechanism of phosphorus, nitrogen and silicone elements in the UV-curable coatings was proposed. This work denotes that it is a good method to develop nitrogen–phosphorus–silicone-containing flame retardant transparent UV-curable materials.

Thermadapt shape memory polymers based on thermally induced dynamic covalent quinone methide–thiol click reaction

A novel thermadapt shape memory polymer networks were prepared based on the conjugate addition reaction of quinone methide (QM) end-group-functionalized polycaprolactone and a thiol cross-linker, which can undergo the dynamic exchange reaction under thermal stimulation conditions. The resultant cross-linked polymers possessed excellent elasticity-based shape memory performance, cycle stability and solid-state plastically characteristics under high temperature conditions. This thermal-induced QM-thiol dynamic covalent click chemistry provided an effective method for realizing the solid-state plasticity of the polymers.

Lithium ion capacitor based on polyoxide-polythiol co-networks

The present article emerges from our recent finding of supercapacitive behavior of polymer electrolyte membranes (PEM) via photo-crosslinking of polyethylene glycol diacrylate (PEGDA) with trimethylolpropane tris(3-mercaptopropionate) (TMPTMP) via thiol-ene click reaction in the presence of succinonitrile (SCN) plasticizer and lithium bis(trifluoromethane sulfonyl imide) (LiTFSI) salt. The photo-cured polymer electrolyte membrane (PEM) co-network revealed a superionic conductor level of 1.26 mS/cm at 23 °C and an elongation at break of around 23%, suggestive of a highly conductive and stretchable character. Upon deep discharging to the potential range of lithium metal anode at −0.5–0.5 V, lithium-ion stripping from the Li metal electrode (i.e, oxidation at 0–0.3 V) affords continuous supply of Li-ions, which not only afford the lithium-ion storage within the PEM through ion-dipole interaction (i.e., temporary holding of Li ions), but also facile ion transport once the complexation sites of Li-ion with ether oxygen and thiols are fully saturated with excess Li-ions. To elucidate a plausible energy storing mechanism of the PEM, the cyclic voltammetry (CV) investigation was performed in the full battery configuration as well as in the symmetric carbonaceous electrode configuration. A novel supercapacitor behavior was noticed in the PEM involving both pseudocapacitor and electric double-layer capacitor (EDLC) types. Last but not least, specific capacitance and specific energy densities from the CV curves were evaluated and discussed.

Effects of thiol‐ene click reaction on morphology and electro‐optical properties of polyhedral oligomeric silsesquioxane nanostructure‐based polymer dispersed liquid crystal film

AbstractPolymer dispersed liquid crystals (PDLCs) have lit a flash of interest due to the distinctive property of electrically controlled switching. However, too high‐driving voltage associated with porous polymer networks always limit their wider range of applications. Herein, we reported a PDLC system containing LCs, 2,2′‐(Ethylenedioxy)diethanethiol (DET) with thiol groups, cage‐like nanostructure acrylic polyhedral oligomeric silsesquioxane (KH570‐POSS) and KH570‐SiO2 nanoparticle modified by acrylic groups. The cage‐like KH570‐POSS microstructure was injected to the polymer matrix when KH570‐POSS reacted with DET via thiol‐ene click reaction. The morphological results demonstrated that the droplet size increased with the higher content of DET due to the decrease of the crosslink between the acrylic groups in KH570‐POSS, which results in a less dense of polymer network and thus make the LC droplets easier to be driven in the electric filed. Then, a silica‐based nanoparticle KH570‐SiO2 modified by acrylic groups was introduced into the system. The results indicated that KH570‐SiO2 could replace partial KH570‐POSS to form the polymer network via thiol‐ene click reaction, which increased the compatible ability of SiO2 nanoparticles in the as‐made film. The contrast ratio was increased to 165 when there was nearly 5 wt% content of KH570‐SiO2. Besides, the driving voltage was reduced by almost 60% and the sample could be fully driven by 30 V which is lower than the safe voltage (36 V). This study opens a route for the preparation of commercial PDLC films by thiol‐ene click reaction, enabling the creation of low‐voltage‐driven smart windows.

Synthesis and characterization of biopolyurethane crosslinked with castor oil-based hyperbranched polyols as polymeric solid–solid phase change materials

Novel crosslinking bio polyurethane based polymeric solid–solid phase change materials (SSPCM) were synthesized using castor oil (CO) based hyperbranched polyols as crosslinkers. CO-based hyperbranched polyols were synthesized by grafting 1-mercaptoethanol or α–thioglycerol via a thiol-ene click reaction method (coded as COM and COT, respectively). Subsequently, the three SSPCMs were synthesized by a two-step prepolymer method. Polyethylene glycol was used as the phase change material in the SSPCMs, while the CO-based hyperbranched polyols and two types of diisocyanate (hexamethylene diisocyanate (HDI) and 4,4'-diphenylmethane diisocyanate) served as the molecular frameworks. Fourier transform infrared spectroscopy indicated the successful synthesis of the SSPCMs. The solid–solid transition of the prepared SSPCMs was confirmed by X-ray diffraction analysis and polarized optical microscopy. The thermal transition properties of the SSPCMs were analyzed by differential scanning microscopy. The isocyanate and crosslinker types had a significant influence on the phase transition properties. The SSPCM samples prepared using HDI and COT exhibited the highest phase transition enthalpy of 126.5 J/g. The thermal cycling test and thermogravimetric analysis revealed that SSPCMs exhibit outstanding thermal durability. Thus, the novel SSPCMs based on hyperbranched polyols have great potential for application as thermal energy storage materials.

Fluorine-free, short-process and robust superhydrophobic cotton fabric and its oil-water separation ability

Superhydrophobic (SH) fabric is widely used in production and life because of its excellent water repellency, self-cleaning, and anti-fouling properties, however, long process and poor durability against repeated laundering and abrasion of SH fabrics remain challenges. In this study, we report a fluorine-free, short-process and robust SH cotton fabric obtained by dip-coating with SH coatings based on UV induced thiol–ene click reactions among 3-mercaptopropyltriethoxysilane (MPTES), octavinyloctasilasesquioxane (OV-POSS) and 2 %–3 % (mercaptopropyl)methylsiloxane-dimethylsiloxane co-polymers (S-PDMS), and the coated fabric is enough durable against repeated laundering, abrasion, chemical corrosion and UV aging. Furthermore, its self-healing ability owing to heat treatment (140 °C, 30 min) can further improve the coating durability, based on which the coating can withstand at least 28 cycles of repeated accelerated washing (equivalent to 140 cycles of normal home laundering) and maintain its superhydrophobicity. Additionally, the coating can separate oil-water mixtures, and the separation efficiency is more than 99 %, even after 10 cycles of repeated oil-water separation processes. The combination of short-process and self-healing ability makes it very promising in the large-scale manufacturing and application of SH surfaces.

Functionally Graded Bioactive Composites Based on Poly(vinyl alcohol) Made through Thiol-Ene Click Reaction.

Functionally graded materials (FGMs) composed of a polymer matrix embedded with calcium phosphate particles are preferred for bone tissue engineering, as they can mimic the hierarchical and gradient structure of bones. In this study, we report the design and development of a FGM based on thiolated poly(vinyl alcohol) (TPVA) and nano-hydroxyapatite (nano-HA) with graded bioactivity, cell compatibility, and degradability properties that are conducive for bone regeneration. The polymer matrix comprises crosslinked poly(vinyl alcohol) with ester and thioether linkages formed via the thiol–ene click reaction, avoiding undesired additives and byproducts. Freshly precipitated and spray-dried HA was mixed with the TPVA hydrogel, and layers of varying concentrations were cast. Upon lyophilization, the hydrogel structure yielded porous sheets of the graded composite of TPVA and nano-HA. The new FGM showed higher values of tensile strength and degradation in phosphate buffer saline (PBS) in vitro, compared to bare TPVA. The bioactive nature of the FGM was confirmed through bioactivity studies in simulated body fluid (SBF), while cytocompatibility was demonstrated with human periodontal ligament cells in vitro. Cumulatively, our results indicate that based on the composition, mechanical properties, bioactivity, and cytocompatibility, the fabricated TPVA-HA composites can find potential use as guided bone regeneration (GBR) membranes.