Thiol-ene Click Reaction Research Articles

Universal approach for developing reprocessable and reprintable plant oil-based resins for digital light processing 3D printing

Recently, researchers have shown great interest in the development of biobased and reprintable 3D printing materials for sustainable 3D printing. Herein, a method for developing plant oil (PO)-based digital light processing (DLP) printing resins that are both reprocessable and reprintable is proposed. Biobased UV-curable monomers (POPITs) containing dynamic hindered urea bonds (HUBs) from POs were synthesized via the thiol-ene click reaction. A range of DLP printing resins (POPIT-I) with high biobased content (52.6%–58.1%) were prepared by blending POPITs with the biobased dilute monomer isobornyl acrylate. These resins demonstrated good mechanical and thermal properties (e.g., tensile strength: 45.1–49.5 MPa and Tg: 74–92 °C), as well as high DLP printing quality. Reprocessable DLP printing was employed to fabricate large-volume parts through the dissociation and reorganization of HUBs, thereby reducing printing difficulty and printing time. Additionally, a powder blending and modification method was used to recycle and reprint printed materials. The printing materials, including printed green parts and discarded supporting materials, were milled into micron-sized powders and then blended with POPIT-I to prepare the powder blending resins. The milled powders in the powder blending resins were further modified by 2-(tert-butylamino) ethyl methacrylate to prepare reprinting resins. This process resulted in the grafting of C = C onto the powder surface, which eliminated heterogeneity between the powders and POPIT-I. The mechanical and thermal properties of the reprinting resins were comparable with those of POPIT-I even after three rounds of recycling. Furthermore, the reprinting method reported here is applicable to other dynamic covalent bond-based 3D printing systems.

Asymmetric Block Extension of Star-Shaped [PEG-SH]4 - toward Poly(dehydroalanine)-Functionalized PEG Hydrogels for Catch and Release of Charged Guest Molecules.

With the incorporation of polyampholytic segments into soft matter, hydrogels can serve as a reservoir for a variety of charged molecules which can be caught and released upon changes in pH value. Asymmetric block extension of one arm for star-shaped poly(ethylene glycol) [PEG26 -SH]4 using short segments of polyampholytic poly(dehydroalanine) (PDha) is herein demonstrated while maintaining the functional thiol end groups for network formation. For subsequent hydrogel synthesis with up to 10wt.% PDha a straightforward and biocompatible photoinitiated thiol-ene click reaction is exploited. The investigation of the swelling properties of the hydrogel revealed responsive behavior toward ionic strength and variations in pH value. Moreover, the reversible adsorption of the model dyes methylene blue (MB) and acid orange 7 (AO7) is investigated by UV-vis measurements and the procedure can be successfully transferred to the adsorption of the adhesion peptide RGDS resulting in an uptake of 1.5 wt% RGDS with regard to the dry weight of the hydrogel.

Indole-functionalized polythiourethane/tetrapodal shaped ZnO nanocomposites for eco-friendly marine biofouling control

Antifouling coatings for marine use are a widely employed method for controlling the settlement and growth of unwanted aquatic organisms on surfaces. In this study, indole derivative N-(1H-5-bromo indole-3-ylmethyl) acrylamide (BIAM)-functionalized polythiourethane (PTU)/tetrapodal shaped zinc oxide (t-ZnO) nanocomposites (PTU/BIAM/t-ZnO) were synthesized through a Friedel–Crafts Alkylation reaction, thiol-ene click reaction and polyaddition reaction. Nanocomposites' surface characteristics, such as surface free energy, chemical composition, and surface morphology were investigated here. The mechanical characteristics and antifouling properties of the coating materials were also considered. These nanocomposites exhibited not only superior mechanical properties, due to the presence of both PTU and t-ZnO, but also promising antifouling properties owing to the incorporation of BIAM on their surfaces. The adhesion strength of the nanocomposites increased from 0.26 MPa to 0.68 MPa due to the incorporation of t-ZnO particles. Benefiting from the PTU matrix, the tensile strength of nanocomposite can reach over 57 MPa. The PTU/BIAM/t-ZnO nanocomposites demonstrated improved algae resistance and marine antifouling performance compared to the reference PTU/t-ZnO nanocomposite without indole derivative. The PTU/BIAM/t-ZnO nanocomposites exhibit resistance to fouling organisms due to the synergistic effect of the easy-to-clean characteristic of the PTU/t-ZnO and the reduction of the polar component of the surface free energy resulting from the inclusion of indole derivative BIAM on the surface. This, in turn, reduces the interaction between fouling organisms and the material surface. Furthermore, BIAM interferes with the homeostasis of cellular calcium ions, thereby hindering the attachment of fouling organisms. Under the combined action of PTU, BIAM, and t-ZnO, the synergistic effect of good antifouling properties, environmental compatibility, good mechanical properties and strong adhesion to the substrate was achieved.

Shape memory polyurethanes crosslinked with castor oil-based multifunctional polyols

As both the industry and academia become more focused on biomass-based smart materials, they are attracting a lot of attention. There has been a significant effort in the field of polyurethane (PU) synthesis to replace polyols used in synthesis with bio-derived polyols. Bio-derived polyols have limited application potential for bio-based PU due to their low functionality. Here, we reported castor oil (CO) based multifunctional polyols prepared by grafting thiols such as 1-mercaptoethanol or α–thioglycerol via a facile thiol-ene click reaction method (coded as COM and COT, respectively). Subsequently, bio-based shape memory polyurethanes (SMPU) crosslinked with prepared polyols were synthesized using a 2-step prepolymer method. By confirming the functionality of the synthesized polyols, it was determined that COT has an OH value of 380 mg KOH/g, which is approximately three times that of CO. The successful synthesis of SMPUs was confirmed through chemical structural analysis. It was also proved that the phase separation between the soft and hard segments was limited due to the increase in crosslinking density. As compared to SMPU crosslinked with CO, the mechanical strength of SMPU crosslinked with COT was improved by 80%, while the elongation was decreased by about 26%. As a result of shape memory behavior analysis, it was confirmed that the outstanding SMPU can be synthesized using CO-based multifunctional polyols.

Hydrophobic cotton fabric with 3-mercaptopropyltriethoxysilane/polyhedral oligomeric silsesquioxane/1-octadecanethiol modification for oil/water separation

A protocol to produce a silsesquioxane (POSS) with a long alkyl chain coating on natural cotton (CT) fabric is applied. The surface hydroxyl groups of cotton fabric are converted with 3-mercaptopropyltriethoxysilane (MPTES) to thiol groups. Then the POSS links to the thiol groups by thiol-ene click reactions triggered by UV irradiation to produce POSS-CT or grafted with 1-octadecanethiol (ODT) using one-pot or two-pot modification protocols to generate the ODT-POSS-CT fabrics. The POSS-CT is highly hydrophobic, could absorb 0.96 g hexane/g fabrics when competing with invaded water, and reach 1.12 hexane g/g fabrics when water was absorbed separately. The one-pot modification protocol yielded surfaces with almost constant water contact angle (144o) and perfect wetting by diiodomethane (0o), producing constant dispersive component (50.8 mJ/m2) and polar component (13.6 mJ/m2). The ODT-POSS-CT via two-pot modification leads to water contact angles >143o and diiodomethane contact angle of about 46o, with corresponding dispersive and polar components being 36.1 mJ/m2 and 9.4 mJ/m2, respectively. The complete grafting of ODT onto POSS yields a compact hydrophobic layer with reduced effective surface area for dispersive components, transferring the surface from hydrophobic to omniphobic for both water and diiodomethane.

Strong Binding of C-Glycosylic1,2-Thiodisaccharides to Galectin-3─Enthalpy-Driven Affinity Enhancement by Water-Mediated Hydrogen Bonds.

Galectin-3 is involved in multiple pathways of many diseases, including cancer, fibrosis, and diabetes, and it is a validated pharmaceutical target for the development of novel therapeutic agents to address unmet medical needs. Novel 1,2-thiodisaccharides with a C-glycosylic functionality were synthesized by the photoinitiated thiol-ene click reaction of O-peracylated 1-C-substituted glycals and 1-thio-glycopyranoses. Subsequent global deprotection yielded test compounds, which were studied for their binding to human galectin-3 by fluorescence polarization and isothermal titration calorimetry to show low micromolar Kd values. The best inhibitor displayed a Kd value of 8.0 μM. An analysis of the thermodynamic binding parameters revealed that the binding Gibbs free energy (ΔG) of the new inhibitors was dominated by enthalpy (ΔH). The binding mode of the four most efficient 1,2-thiodisaccharides was also studied by X-ray crystallography that uncovered the unique role of water-mediated hydrogen bonds in conferring enthalpy-driven affinity enhancement for the new inhibitors. This 1,2-thiodisaccharide-type scaffold represents a new lead for galectin-3 inhibitor discovery and offers several possibilities for further development.

Synthesis and characterization of some thioether compounds by thiol-ene click chemistry

In this study, some thioether compounds were prepared by thiol-ene click reaction using cheap starting materials from natural source or plastic waste such as limonene from orange peel, and styrene by thermal degradation (cracking) of plastic waste like spoon and fork plastic, and different reaction conditions were achieved, some starting material did not need any catalyst or heat like limonene reacts with thioglycolic acid to give 2-(4-methylcyclohex-3-en-1-yl)propyl)thio)acetic acid , where the reaction was exothermic and very fast, while the styrene need the catalyst such as water or glycerol to start the reaction with thioglycolic acid through nucleophilic addition to give 2-(phenethylthio)acetic acid . The synthesized thioether compounds were prepared in high yield through anti-Markonickov rule at room temperature and diagnosed by FT- IR and H-NMR .

Development of 3D Printable Highly Flexible Siloxane Elastomers for Direct Ink Writing (DIW) of Soft Robotic Actuators for Space Applications

There is an interest in soft robotics for various space applications within low gravity and tight space environments to navigate, observe and even service various components within space assets, spacecraft and planetary stations. As an example, in an emergency, such as a pipe system failure occurring in a spacecraft, a soft robot may be able to assist in navigating the structure to detect the location and means of failure. The manufacturing of soft robotic actuators in space can be crucial. In addition, the fabrication of soft robotic tooling in a single step plays a critical role in space. 3D printing systems allow the manufacturing of soft robotic actuator parts in a single step. Stereolithography (SLA) and digital light processing (DLP) systems are not convenient because of the space environment. However, direct ink writing (DIW) which is the most commonly available and affordable system compared to SLA or DLP can be utilized to produce 3D objects, in addition, the DIW process permits the ability to in situ produce composite structures during the printing process. Various inorganic particles can be inserted within the elastomer print to control the mechanical, electrical and magnetic properties on-demand to produce smart or multi-functional soft robotic actuators and structures.The current work focuses on the development of a highly flexible and low (or nearly no) cytotoxicity silicone-based elastomer via thiol-ene click reaction that allows rapid polymerization of an elastomer to prevent the collapse of the structure during the printing. The work also demonstrates the use of this novel UV-durable elastomer to produce structures with embedded electrical interconnects and sensors for in-situ measurement of temperature and strain. In this study Poly(mercaptopropylmethylsiloxane-co-dimethylsiloxane) (M-MPS) was first prepared through the cohydrolysis-condensation reaction of 3-Mercaptopropylmethyltrimethoxysilane (MPS) and dimethyldimethoxylsilane (DMDES) with water and hydrochloric acid. Then M-MPS was compounded with various molecular weight vinyl-terminated polydimethylsiloxane (VPS) (MW~800-25000) and different dosage (0.1- 4.0 wt%) of a photoinitiator (1:1 weight ratio of 2-Hydroxy-2-methyl-phenyl-propane-1-one (PI 1173) and phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide (PI819)). For example, Figure 1 depicts the change in the viscosity of (M-MPS)-VPS 6000 2 wt% when it exposes to UV light irradiation. When (M-MPS)-VPS 6000 2 wt% was exposed to UV light irradiation, it polymerized at ~2 sec which is enough time to retain the structure during printing. To elucidate the properties of synthesized elastomer, FTIR, NMR, SEM, and tensile test measurements were performed. Furthermore, the synthesized elastomer was loaded with conductive inorganic particles so as to utilize the printed material as a temperature and tactile sensor (and sensor array). In addition, other printing variables were evaluated to produce 2D/3D structures of the pure and composite elastomers, such as the effect of the power and wavelength of UV light source, loading different types of conductive powders, and thiol-ene ratio. Acknowledgments: Work supported by a subcontract under the NASA-EPSCOR program (project number is 80NSSC20M0218). The authors would like to thank our NASA technical monitor Mr. Curtis Hill and project manager Dr. Melanie Page due to their contributions. Material characterization and imaging work were made possible with the support of the West Virginia University Shared Research Facilities (SRF). Figure 1

Highly Conductive Polysiloxane Elastomers with Excellent Transparency, Resilience, and Stretchability.

Flexible transparent conductive materials show great potential in wearable electronics, flexible sensors, and so on. But the most used flexible conductive materials like hydrogels and ionogels suffer from evaporation and solvent leakage. For the application in these fields, integrated performances of preeminent resilience, transparency, stability, and conductivity that do not change with deformation are prerequisites. It is still challenging to handle the trade-off among these performances. Herein, a facile approach is established to balance these properties into one elastomer. Through the thiol-ene click reaction, mercaptopropyl-modified polydimethylsiloxane (mPDMS) is cross-linked and grafted by PEG-based macromonomers to prepare conductive elastomers. By anchoring with mPDMS through carbon-sulfur bonds, PEG can be evenly dispersed, resulting in ultratransparency (97%) and stable conductivity of as high as 1.68 × 10-2 S m-1, comparable to pure PEG/lithium salt conductivity. It also has a wide electrochemical stability window with a high voltage of 4.8 V. Moreover, the multibond network strategy is employed through grafting ligand 1-vinylimidazole to mPDMS to construct dynamic cross-links between Zn(II) and 1-vinylimidazol, bestowing excellent properties to the elastomers. Overall, elastomers with a well-balanced performance of high resilience, good conductivity, and ultratransparency are obtained, providing promising applications for soft electronics, lithium battery electrolytes, and flexible devices.

Direct photocatalytic patterning of colloidal emissive nanomaterials.

We present a universal direct photocatalytic patterning method that can completely preserve the optical properties of perovskite nanocrystals (PeNCs) and other emissive nanomaterials. Solubility change of PeNCs is achieved mainly by a photoinduced thiol-ene click reaction between specially tailored surface ligands and a dual-role photocatalytic reagent, pentaerythritol tetrakis(3-mercaptopropionate) (PTMP), where the thiol-ene reaction is enabled at a low light intensity dose (~ 30 millijoules per square centimeter) by the strong photocatalytic activity of PeNCs. The photochemical reaction mechanism was investigated using various analyses at each patterning step. The PTMP also acts as a defect passivation agent for the PeNCs and even enhances their photoluminescence quantum yield (by ~5%) and photostability. Multicolor patterns of cesium lead halide (CsPbX3)PeNCs were fabricated with high resolution (<1 micrometer). Our method is widely applicable to other classes of nanomaterials including colloidal cadmium selenide-based and indium phosphide-based quantum dots and light-emitting polymers; this generality provides a nondestructive and simple way to pattern various functional materials and devices.

Novel ricinoleic acid highly functionalized hierarchical SiO2 with switchable superwettability for removal of oils, heavy metal ions, and organic dyes from water

It remains a challenge to explore a low-cost and green approach to prepare stimuli-responsive materials that can meet increasingly complicated separation demands. Herein, we report a facile method to prepare pH-responsive silica particles modified by abundant carboxyl groups (SiO2-COOH), which are introduced from bio-based ricinoleic acid via an efficient and mild thiol-ene click reaction. The hierarchical structure of SiO2-COOH can easily construct roughness that is essential for special wettability, which is demonstrated by the robust superhydrophobicity achieved synergistically with non-pH-responsive binder on different substrates and no significant change after 100 peels or extrusions. We also present the efficient separation of different oil–water mixtures by modified fabrics and sponges, respectively, based on their fast wettability transition within seconds at different pH. More importantly, benefiting from the chelation of carboxyl and hydroxyl groups from ricinoleic acid molecules and large specific surface area provided by the hierarchical structure, SiO2-COOH and its different alkali treatment products exhibit outstanding adsorption capacity to heavy metal ions and organic dyes, of which up to 180 mg/g for Pb2+. It is believed that the proposed novel and eco-friendly method is a promising candidate for the simultaneous removal of multiple pollutants from oily wastewater.

Interfacial properties of PPBES/CF composites reinforced by ammonified carbon fibers through thiol-ene click reaction

Our previous work has shown that the amino group is beneficial to improve the interface properties of PPBES/CF composites. However, the existing methods for introducing amino groups have many reaction steps, long reaction time and harsh reaction conditions. A one-step efficient click reaction can effectively avoid the above disadvantages. In this paper, 2-aminoethanethiol (AET) was grafted to CF via a thiol-ene click reaction. The reaction time has been reduced from over 9 h to just 1.5 h. The successful introduction of amino group into CF was testified by FTIR, Raman and XPS. The influence of different ratios of CF:AET on the interfacial properties of the composites was studied emphatically. When CF: AET was 1:3 (T3), the composite exhibited optimal mechanical properties. The ILSS and flexural strength of the resulting composite increased by 24.45% and 33.1%, respectively. The Tg of the PPBES/T3 composite was increased to 242 °C as verified by DMA.

Hydrophobic/hydrophilic separation performance evaluation of a mixed-mode ionic liquid embedded stearyl thioglycolate functionalized silica stationary phase

In this work, a novel imidazolium ionic liquid embedded multifunctional chromatographic stationary phase (Sil-AVI-ST) was synthesized by the radical-mediated thiol-ene click reaction. A wide range of samples including hydrophilic sulfonamides, vitamins and nucleosides/bases as well as hydrophobic phthalates, bisphenols, alkylphenols and steroid hormones were selected to evaluate the separation ability of the newly obtained Sil-AVI-ST. As expected, an efficient separation of the above tested analytes was successfully achieved in different chromatographic modes. It was proved that multiple stationary phase-analyte interaction forces promoted the selective separation. The Sil-AVI-ST column provided multiple retention mechanisms, enabling the efficient separation of diverse analytes with different polarity. More importantly, embedding a polar ligand (1-allyl-3-vinyl-imidazolium) could improve the separation efficiency of long-chain alkyl bonded stationary phases for hydrophilic analytes, and the developed Sil-AVI-ST column could also realize the detection of hydrophobic analytes under water-rich conditions, which is impossible for the conventional hydrophobic columns. Therefore, the newly prepared Sil-AVI-ST stationary phase has a good practical application potential.

A novel pillar[3]trianglimine macrocycle with a deep cavity used as a chiral selector to prepare a chiral stationary phase by thiol-ene click reaction for enantioseparation in high-performance liquid chromatography.

A chiral pillar[3]trianglimine (C60 H72 N6 O6 ) with a deep cavity has been developed as a chiral selector and bonded to thiolated silica by thiol-ene click reaction to fabricate a novel chiral stationary phase for enantioseparation in high-performance liquid chromatography. The enantioseparation performance of the fabricated chiral stationary phase has been evaluated by separating various racemic compounds, including alcohols, esters, amines, ketones, amino acids, and epoxides, in both normal-phase and reversed-phase elution modes. In total, 14 and 17 racemates have been effectively separated in these two separation modes, respectively. In comparison with two widely used chiral columns (Chiralcel OD-H and Chiralpak AD-H), our novel chiral stationary phase offered good chiral separation complementarity, separating some of the tested racemates that could not be separated or were only partially separated on these two commercial columns. The influences of analyte mass, mobile phase composition, and column temperature on chiral separation have been investigated. Good repeatability, stability, and column-to-column reproducibility of the chiral stationary phase for enantioseparation have been observed. After the fabricated column had been eluted up to 400 times, the relative standard deviations (n=5) of resolution (Rs) and retention time of the separated analytes were<0.39% and<0.20%, respectively. The relative standard deviations (n=3) of Rs and retention time for column-to-column reproducibility were<4.6% and<5.2%, respectively. This study demonstrated that the new chiral stationary phase has great prospects for chiral separation in high-performance liquid chromatography.

Green preparation of composite hydrogel coated hydrophobic long-chain carboxylic acid-bonded silica microspheres for mixed-mode chromatography

Combining composite hydrogel with silica gel can endow hydrogel with new application possibilities. In this work, polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) were combined into a composite hydrogel, which was then wrapped on the surface of 1-undecenoic acid (UA) bonded silica microspheres. As a result, a novel PVP/PVA composite hydrogel-functionalized silica stationary phase (PVP/PVA@Sil-UA) was prepared by a green and facile method. Specifically, the thiol-ene click reaction was preferentially used to bond a hydrophobic long-chain carboxylic acid (UA) on the surface of thiolated silica gel in deep eutectic solvent, which was able to provide abundant hydrogen bonding sites for the further coating of PVP/PVA composite hydrogel. The hydrophobic long alkyl chain not only improved the separation selectivity, but also effectively alleviated the swelling of hydrogel. It was discovered that the prepared PVP/PVA@Sil-UA showed outstanding separation performance for a wide range of samples. The study of retention behavior proved that the PVP/PVA@Sil-UA was a mixed-mode chromatographic stationary phase, possessing hydrophilic and hydrophobic retention characteristics. In summary, an eco-friendly method was applied to realize the effective combination of composite hydrogel and SiO2 due to the fact that no harmful organic solvents were used in the preparation process, which provided a novel idea for the application of composite hydrogel in the field of chromatographic separation.

Constraining effects on polymer chain relaxation in crosslinked supramolecular dual networks

Polymer networks containing transient physical and permanent chemical cross-links exhibit unique mechanical properties due to the intrinsic reassociating ability of supramolecular functional groups. Similar to supramolecular gels, these networks allow the controlled release of stored energy and can extend the life of polymer networks in practical applications. In this study, we investigated the rheology, dielectric spectroscopy, stress–strain behavior, and dynamic mechanical analysis of networks based on long polybutylene oxide (PBO) chains functionalized with randomly placed thymine (Thy) side groups. A transient network was formed by proportionally mixing this matrix with short non-entangled linear 1,3,5-diaminotriazine (DAT) head–tail modified PBO chains, exploiting the hetero-complementarity of the DAT–Thy triple hydrogen bond. This transient polymer network was further cross-linked to a dual network via a thiol-ene click reaction to form static covalent bonds. In PBO, the similar polarity of the PBO matrix and the DAT–Thy functional groups ensures that the molecular chain motion is not affected by segregation, resulting in a homogeneous polymer phase without microphase-separated functional group domains. Dielectric relaxation spectroscopy was combined with rheology to quantify the relaxation processes of the interconnected polymers and the strength of the DAT–Thy bonding interactions in the melt. The results showed two distinct plateaux in the relaxation modulus due to contributions from hydrogen and permanent bonds. In the case of the dual network, the lifetime of the hydrogen bond was prolonged and higher activation energy was observed due to the physical cross-link preventing the movement of the long chain.

Swan feather-spired fluorine-free superhydrophobic self-cleaning cotton cloth with strong oil-water separation function

With the increasing demand of oil-water separation, superhydrophobic materials have garnered tremendous research attention due to their excellent oil-water separation efficiency. However, the biological toxicity and poor durability of fluorine-containing compounds in superhydrophobic materials severely restrict their application. In this work, inspired by the superhydrophobic/lipophilic swan feathers, we proposed a two-stage thiol-ene click reaction strategy to fabricate a fluorine-free superhydrophobic and super-lipophilic oil/water separation membrane (Cotton-S-PB-SiO2). Firstly, based on this thiol-ene click reaction, the rubber molecular chain 1,2-polybutadiene (1,2-PB) with low surface energy was coated with cotton fiber through chemical bonds. Subsequently, the coated cotton fiber was employed to establish chemical bonds with silica. The Cotton-S-PB-SiO2 possessed low surface energy and abundant micro-nano structures. Meanwhile, the Cotton-S-PB-SiO2 showed extremely high wettability selectivity to water and oil phases. The flux reached 44,554 L m−2 h−1, and the separation efficiency for immiscible oil/water mixtures was above 99.9 %. More remarkably, the Cotton-S-PB-SiO2 demonstrated excellent anti-fouling and operation stability even under some harsh environments such as strong acid, alkali, salt, etc. The prepared self-cleaning cotton cloth provides insights toward mild, low-cost and high-efficiency oil-water separation.

Dithiol cross-linked polynorbornene-based anion-exchange membranes with high hydroxide conductivity and alkaline stability

Vinylic-addition polynorbornenes possess high thermal stability, excellent mechanical integrity, and chemically inert backbones. Herein, we conveniently synthesize a series of vinylic-addition polynorbornene copolymers containing pendant alkenes from commercial vinyl-substituted norbornene (VNB) and alkyl-bromide-substituted norbornene (BrNB). Subsequently, the copolymers are photo-crosslinked with dithiol reagents through UV-initiated thiol-ene click reactions followed by quaternization to prepare the cross-linked anion-exchange membranes (AEMs). The extent of cross-linking and the hydrophobicity of the cross-linkers can be easily controlled, so that the absorption of excess water can be inhibited with enhanced membrane strength. The resultant AEMs have ultrahigh hydroxide conductivities (up to 199 mS/cm at 90 °C under humidified conditions) and excellent alkaline stability in 1 M KOH at 80 °C for 1200 h. The vinylic-addition AEMs are also successfully applied in alkaline anion-exchange membrane water electrolyzers with commercial noble-metal-free electrocatalysts.

High solid and low viscosity waterborne polyurethane acrylate with excellent anti-corrosion and anti-bacterial performances

The design and preparation of great corrosion resistance and high-solid waterborne polyurethane dispersion with low viscosity is still a challenge in the field of the polyurethane industry. Herein, we developed a simple method involving a core-shell process to prepare a core-shell structured waterborne polyurethane acrylate dispersion (WPUAD). First, isobornyl acrylate, a derivative of natural product borneol, dihydroxylated by a thiol-ene click reaction was used to prepare oil-based polyurethane acrylate as prepolymer A (core) and waterborne polyurethane acrylate as prepolymer B (shell). Then, the core-shell WPUAD was obtained by mixing and emulsifying the two prepolymer at a certain ratio. The study reveals that the core-shell structured WPUAD not only has a low viscosity (~1330 mPa.s) but also holds a high-solid content (~ 60 wt%). At the same time, the highly solid WPUAD has excellent stability with no breast breakage even after more than 1 year of storage. In addition, various electrochemical measurements, water contact angles, and water absorption tests were performed to determine the anti-corrosive properties of the WPUAD-derived coatings. The results show that the WPUA coatings exhibit significantly enhanced anticorrosion with respect to the single prepolymer B derived coatings, which is attributed to their high cross-linking density resulting from the core-shell structure and the introduction of hydrophobic isobornyl acrylate. In addition, because of the introduction of the dihydroxylated isobornyl acrylate as chain extenders, the WPUA coating has great anti-bacterial adhesion properties with an anti-bacterial efficiency of 82.3 %. We believe that our work provides a generic preparation method to obtain a commercially available high-solid WPUAD with excellent anti-corrosion properties.

One-pot and one-step preparation of “living” cellulose nanofiber hydrogel with active double-bond via chemical vapor deposition

Due to the existence of water, it is still a challenge to conduct chemical modification on cellulose nanofiber (CNF) hydrogels with active double bonds. A simple one-pot and one-step method for constructing “living” CNF hydrogel with double bond was created at room temperature. The chemical vapor deposition (CVD) of methacryloyl chloride (MACl) was used to introduce physical-trapped, chemical-anchored and functional double bonds into TEMPO-oxidized cellulose nanofiber (TOCN) hydrogels. TOCN hydrogel could be fabricated within just 0.5 h, the minimum dosage of MACl could be reduced to 3.22 mg/g (MACl/TOCN hydrogel). Furthermore, the CVD methods showed high efficiency for mass production and recyclability. Moreover, the chemical “living” reactivity of the introduced double bonds were verified by the freezing and UV crosslinking, radical polymerization and thiol-ene click reaction. Compared with pure TOCN hydrogel, the obtained functionalized TOCN hydrogel exhibited remarkable improvements in mechanical properties, with enhancements of 12.34 times and 2.04 times, as well as an increase in hydrophobicity by 2.14 times and a fluorescence performance improvement of 2.93 times.