Thiol-ene Click Reaction Research Articles

A Study on the Dual Thermo- and pH-Responsive Behaviors of Well-Defined Star-like Block Copolymers Synthesize by Combining of RAFT Polymerization and Thiol-Ene Click Reaction.

A series of stimuli-responsive star-like block copolymers are synthesized via the combination of reversible addition, fragmentation chain transfer (RAFT) polymerization, and photo-initiated thiol-ene (PITE) click reaction. The controllable block ratio and block sequence, narrow distribution of molecular weight, and customized arm numbers of the star-shaped copolymers reveal the feasibility and benefits of combination of RAFT polymerization and PITE click reaction for synthesis of well-defined star-like (co)polymers. A clear insight into the relationship among the arm number, block sequence, and block ratio of the star-like block copolymers and their stimuli-responsive aggregation behavior was achieved via dynamic light scattering and UV-vis spectroscopy study. Notably, the star-like poly(acrylic acid)-b-poly(2-(dimethylamino) ethyl methacrylate) (star-PAA-b-PDMAEMA) shows higher lower critical solution temperature (LCST) compared to star-PDMAEMA-b-PAA with the same arm number and block ratio due to the inner charged PAA segments at pH > IEP. In addition, for star-like PAA-b-PDMAEMA, higher PAA content enhances the hydrophilicity of the polymer in basic solution and leads to the LCST increase, except for star-PAA1-b-PDMAEMA4 at pH = 9.0 (IEP). For star-PDMAEMA-b-PAA, the PAA content shows minimal effect on their LCSTs, except for the polymer in solution with pH = 9.5, which is far from their IEP. The star-like block copolymers with well-defined structure and tunable composition, especially the facile-controlled block sequence, bring us a challenging opportunity to control the stimuli-responsive properties of star-like block copolymers.

N-Vinylcarbazole in thiol-ene click reactions: A versatile additive for sunlight-cured luminescent coatings and information encryption

N-Vinylcarbazole (NVK) has been shown to be an ideal candidate for the sunlight-induced thiol-ene click reactions, in which it simultaneously plays the role of both a photoinitiator and a monomer. The former role of NVK brings the increased efficiency of fluorescent-brightener-mediated thiol-ene polymerizations under sunlight exposure, more interesting, this excellent performance realizes the high value utilization of natural sunlight, thereby opening new opportunities for the applications of thiol-ene click reactions. Meanwhile, the latter role of NVK affords a novel yet facile approach to prepare luminescent coatings in a green and sustainable way, whose fluorescence color could be alterable by varying the photocurable formulations. Based on the characteristics of the blue fluorescence emitted by polyvinylcarbazole, the resulting poly(thioester-co-carbazole) shows favorable attributes and holds great potential for the applications in the field of information encryption transmission.

Preparation of Stable POSS-Based Superhydrophobic Textiles Using Thiol-Ene Click Chemistry.

In this study, a superhydrophobic fabric was synthesized by modifying the fiber’s surface with dopamine-containing hydroxyl functional groups. Furthermore, we introduced mercapto-based functional groups by the hydrolysis of mercaptopropylmethyldimethoxysilane (MPMDS) and finally grafted POSS and mercaptans using a thiol–ene click reaction. These processes generated a superhydrophobic fabric with a static contact and a sliding angle of 162° and 8°, respectively. The superhydrophobic fabric’s compact and regular micro-nano rough structure based on POSS and mercaptans provides stable fastness and durability, as well as high resistance to organic solvents, acid–base environments, mechanical abrasion, UV rays, and washing. Moreover, it can be used for self-cleaning and oil–water separation, and it has a wide range of applications in the coating industry.

Nanogels loading 5-Fluorouracil in situ through thiol-ene click reaction and photopolymerization at 532 nm for its controlled release

Drug-loaded nanogels have attracted extensive research interest and shown great potential for many biomedical applications. A facile preparation method for drug-loaded nanogels is desirable to be developed. In this study, a range of nanogels were prepared by combining thiol-ene click reaction and photopolymerization at 532 nm for in situ loading 5-Fluorouracil (NG-S). The drug loading amount was improved by introducing mercaptosuccinic acid (MCA) to trigger thiol-ene click reaction. The drug loading capacity and swelling ratio characteristics of NG-S could be tuned by changing the proportion of PEGDA/MCA and the initial dose of drug. Especially, the drug release performance of the NG-S showed that 5-Fluorouracil presented the relatively excellent behavior of controlled release with a sustained release time up to 20 h in PBS (pH 7.4) at 37 °C. The fitting results of NG-S based on R2 were consistent with the First order, Weibull and Biexponential kinetic models.

Preparation and application of polystyrene-divinylbenzene sorbent with weak cation-exchange character for the selective extraction of illicit drugs in environmental water

A novel mixed-mode weak cation-exchange sorbent (PS-DVB-WCX-II) was prepared by the modification of polystyrene-divinylbenzene with mercaptosuccinic acid for the selective extraction of illicit drugs in environmental water. The PS-DVB-WCX-II was synthesized through the Friedel-Crafts acylation reaction on the surface of polystyrene-divinylbenzene, followed by nucleophilic substitution reaction and thiol-ene click reaction. The sorbent can selectively absorb illicit drugs through the reverse-phase interactions provided by benzene ring on the polymer backbone and the ion-exchange interactions provided by functional group (-COOH). As compared with the extraction performance of three commercial SPE cartridges, it was found that the prepared sorbent had better adsorption performance with the recovery values between 84.1% and 106.0% for the selected 11 illicit drugs under the optimized SPE conditions. Illicit drugs in environmental water were extracted by the sorbent, prior to the detection of UHPLC-MS/MS. Two quantitative methods were established respectively for the detection of 11 illicit drugs in different matrices of river water and wastewater. Both methods had good determination coefficient (r2>0.992) in the range of 0.5–50 ng/L, 2.5–250 ng/L, 5–500 ng/L, and low limits of detection (S/N = 3) of 0.17–1.67 ng/L. In the real wastewater samples, the concentration of morphine was 18.3–126.3 ng/L, and the methamphetamine was 12.7–27.4 ng/L. Meanwhile, PS-DVB-WCX-II was compared with Oasis MCX and Oasis HLB in the detection of real wastewater samples. The results revealed that PS-DVB-WCX-II and Oasis MCX had better performance in absorbing methamphetamine than Oasis HLB, and PS-DVB-WCX-II had better ability to remove the matrix. The results suggested that the prepared weak cation-exchange sorbent had the potential in the application of illicit drug detection in environmental water.

Superior stable, hydrophobic and multifunctional nanocellulose hybrid aerogel via rapid UV induced in-situ polymerization

Nanocellulose-based aerogels are potential candidates for the various advanced fields, but the poor structural stability and hydrophily restrains the practical applications. Herein, we report a facile strategy to in-situ polymerizes the polydimethylsiloxane on the anisotropic nanocellulose/chitosan aerogel matrix via UV-induced thiol-ene click reaction in 30 s. A superhydrophobic and elastic nanocellulose-based aerogel with a “stiff-soft” double network structure was fabricated. The inherited porous anisotropic structure and chemical-bonded interlocking interface render the hybrid aerogels with ultralight (9.42 mg/cm3), high porosity (99.29%), and hydrophobicity (contact angle of ~168.0°). Moreover, the hybrid aerogel demonstrated robustness (321 kPa), brilliant elasticity (full recovery from 80% compression), outstanding structure stability (>1000 cycles of compression). The reported strategy paves a new way for fabricating high-performance nanocellulose-based aerogel used for thermal insulation and oil absorption in harsh conditions.

Preparation of Novel Chiral Stationary Phases Based on the Chiral Porous Organic Cage by Thiol-ene Click Chemistry for Enantioseparation in HPLC.

Porous organic cages (POCs) are an emerging class of porous materials that have aroused considerable research interest because of their unique characteristics, including good solubility and a well-defined intrinsic cavity. However, there have so far been no reports of chiral POCs as chiral stationary phases (CSPs) for enantioseparation by high-performance liquid chromatography (HPLC). Herein, we report the first immobilization of a chiral POC, NC1-R, on thiol-functionalized silica using a mild thiol-ene click reaction to prepare novel CSPs for HPLC. Two CSPs (CSP-1 and CSP-2) with different spacers have been prepared. CSP-1, with a cationic imidazolium spacer, exhibited excellent enantioselectivity for the resolution of various racemates. Twenty-three and 12 racemic compounds or chiral drugs were well enantioseparated on the CSP-1-packed column under normal-phase and reversed-phase conditions, respectively, including alcohols, diols, esters, ethers, ketones, epoxides, organic acids, and amines. In contrast, chiral resolution using CSP-2 (without a cationic imidazolium spacer)-packed column B was inferior to that of column A, demonstrating the important role of the cationic imidazolium spacer for chiral separation. The chiral separation capability of column A was also compared with that of two most popular commercial chiral columns, Chiralpak AD-H and Chiralcel OD-H, which exhibits good chiral recognition complementarity with the two commercial chiral columns. In addition, five positional isomers dinitrobenzene, nitroaniline, chloroaniline, bromoaniline, and iodoaniline were also well separated on column A. The effects of temperature, mobile phase composition, and injected analyte mass for separation on column A were investigated. Column A also showed good stability and reproducibility after repeated injections. This work demonstrates that chiral POCs are promising chiral materials for HPLC enantioseparation.

An efficient clean and sustainable methodology for catalytic C-C coupling process over a Pd-free magnetically recoverable cobalt catalyst

The Suzuki and Sonogashira coupling reactions are important processes in organic synthesis. However, to date, these reactions have been extensively examined using Pd-based catalysts in toxic organic solvents. Therefore, developing clean and inexpensive methodologies for these reactions remained a major challenge. Herein, by taking the advantages of thiol-ene click reaction, an easy and robust strategy for surface modification of magnetic graphene oxide with a dendrimer structure was successfully developed. Dendrimer-functionalized magnetic graphene oxide was then applied for the immobilization of Co nanoparticles. Transmission electron microscopy exhibited a homogeneous distribution of Co nanoparticles with the size of about 3 nm. The resultant nanocomposite revealed high efficiency in catalytic Suzuki and Sonogashira reactions in non-hazardous and sustainable deep eutectic solvents (DESs). The DES and catalyst were simply recycled five times with gradual slight decrease in the yield of the reactions. More importantly, the catalyst was magnetically isolated at the end of the recycling process. Overall, the utilization of DES as an environmentally friendly and recoverable reaction medium, as well as replacing the low-cost cobalt catalyst as an alternative to expensive Pd catalyst along with the facile catalyst isolation by employing an external magnetic field, make the present protocol promising from economic and green chemistry points of view for the clean C-C coupling reactions.

Combining reversible addition-fragmentation chain transfer polymerization and thiol-ene click reaction for application of core-shell structured VO2@polymer nanoparticles to smart window

Vanadium dioxide (VO2) can be considered as one of the best candidates for thermochromic smart windows. However, there remain a few limitations that hinder its real application, such as poor stability, low solar modulation efficiency, and weak compatibility with organic polymer matrix. To solve the above-mentioned problems, core-shell structured VO2@PMMA-b-PHFBMA nanoparticles with excellent properties are prepared by a reversible addition-fragmentation chain transfer (RAFT) polymerization, combined with a thiol-ene click reaction. The F-containing polymer shell can effectively reduce the surface energy and stabilize the obtained VO2 nanoparticles. The durability and acid resistance of the VO2 nanoparticles are highly enhanced by the “shield protection” of CF chains, which also improves their compatibility with organic polymer matrix. In addition, PMMA-b-PHFBMA-b-PSPA copolymer chains with photochromic and hydrophobic properties are also prepared by the RAFT polymerization. Through a layer-by-layer coating technique, a PMMA-b-PHFBMA-b-PSPA thin layer can be coated onto a VO2@PMMA-b-PHFBMA/PVB thin layer as an energy-saving coating. The composite film is capable of modulating visible region and near-infrared region, achieving solar modulation efficiency (ΔTsol) up to 20.34%, which is highly promising application for smart windows.

Click chemistry assisted organic-inorganic hybrid photoresist for ultra-fast two-photon lithography

Although the development of two-photon lithography (TPL) for decades of years, fabrication of 2D micro architectures with high throughput is still challenging, due to the lack of suitable photoresists for ultra-fast TPL. In present work, curable zirconia nanoclusters (Zr-NCs) and click-chemistry were incorporated together to form an organic-inorganic hybrid photoresist. Interestingly, Zr-NCs endowed photoresists higher photosensitivity by means of improving the adsorption capacity and reducing the absolute fluorescence quantum yield of used initiator. Moreover, oxygen inhibition had been eliminated by effective thiol-ene click reaction. As a result, the maximum lithography speed of achieved photoresist was significantly enhanced to 2.0 m s −1 , that was dozens of times higher than the reported TPL photoresists. Meanwhile, the photoresist also exhibited a distinguish minimum feature size (59 nm), attributed to high sensitivity and inhibited diffusion of free radical in solid photoresist film. Finally, a high quality micro QR code had been successful prepared by our photoresist at 1.0 m s −1 , which can be recognized to visit the affiliated website. Therefore, this work might provide an alternative strategy to pave the way of ultra-fast 2D TPL. • 5 nm curable zirconia nanocluster incorporated to achieve high-quality photoresists. • Curable zirconia nanocluster endows photoresists higher photosensitivity. • Oxygen inhibition is eliminated by laser induced thiol-ene click-chemistry. • Ultra-fast two-photon lithography (2.0 m s −1 ) and remarkable feature size (59 nm).

Preparation of modified hydrotalcite based on click chemistry and its effect on the shear induced crystallization, rheological behavior and thermal degradability of poly (lactic acid) film

ABSTRACT In this work, Zn-Mg-Al-LDHs was prepared by co-precipitation. LDHs-B-OM was prepared with Zn-Mg-Al-LDHs by coupling method and thiol-ene click chemical reaction. The optimum conditions of thiol-ene click reaction were determined by orthogonal experiment as follows: reaction time of 5 h, mass ratio of OM to B-LDHs of 1: 1, mass ratio of LDHs-B to initiator of 100: 9. LDHs-B-OM was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy, scanning electronic microscope, and static contact angle, which showed that its surface modification was confirmed successfully. Then, PLA/LDHs-B-OM films were prepared by blow molding process using LDHs-B-OM as fillers and PLA as matrix. The mechanical properties, rheological properties, and crystallization behavior of PLA/LDHs-B-OM films were studied, which showed that the elongation at break, the tensile strength of PLA0 and PLA4 (0.7 wt% LDHs-B-OM) were 14.20%, 36.47 MPa, 74.09%, and 46.99 MPa, respectively, which demonstrated that LDHs-B-OM had a significant strengthening and toughening effect on PLA. Rheological behavior results showed that LDHs-B-OM effectively promoted the movement of PLA molecular chain. The shearinduced crystallization behavior and thermal degradation was analyzed by simultaneous rheology and FTIR technology, which showed that the carbonyl peak shifted from amorphous region to crystalline phase region. The reason was that LDHs-B-OM acted as a nucleating agent to accelerate the crystallization process of PLA. The carbonyl index reduction of PLA0 and PLA4 before and after thermal degradation was 14.93% and 7.97%, respectively, which provided sufficient evidence that the addition of LDHs-B-OM improved thermal stability of PLA.

Tough Photo-Cross-Linked PCL-Hydroxyapatite Composites for Bone Tissue Engineering.

Acrylate-based photo-cross-linked poly(ε-caprolactone) (PCL) tends to show low elongation and strength. Incorporation of osteo-inductive hydroxyapatite (HAp) further enhances this effect, which limits its applicability in bone tissue engineering. To overcome this, the thiol-ene click reaction is introduced for the first time in order to photo-cross-link PCL composites with 0, 10, 20, and 30 wt % HAp nanoparticles. It is demonstrated that the elongation at break and ultimate strength increase 10- and 2-fold, respectively, when the photopolymerization mechanism is shifted from a radical chain-growth (i.e., acrylate cross-linking) toward a radical step-growth polymerization (i.e., thiol-ene cross-linking). Additionally, it is illustrated that osteoblasts can attach to and proliferate on the surface of the photo-cross-linked PCL-HAp composites. Finally, the incorporation of HAp nanoparticles is shown to reduce the ALP activity of osteoblasts. Overall, thiol-ene cross-linked PCL-HAp composites can be considered as promising potential materials for bone tissue engineering.

High-efficient lignin-based polymerizable macromolecular photoinitiator with UV-blocking property for visible light polymerization

Developing high-efficient visible light macromolecular photoinitiator (macro PI) with excellent initiation performance, low migration, high biosafety and multi-function is beneficial to broaden the application of photopolymer. Lignin contains chromophores which could generate free radicals under light irradiation. In this study, a lignin-based polymerizable macro PI (DAL-11ene-amine) was designed and synthesized through covalent grafting 10-undecenoyl chloride (11ene) and hydrogen donor 4-(dimethylaminobenzoic acid) ethyl ester (EDAB) into dealkaline lignin (DAL) skeleton. The structure of DAL-11ene-amine was characterized by UV–vis, FTIR, 1H NMR, GPC, and 31P NMR spectra. Under the irradiation of a 405 nm LED, DAL-11ene-amine can directly produce active species and initiate the polymerization of acrylate monomers or thiol-ene click reaction. The photoinitiation efficiency of DAL-11ene-amine is higher than that of DAL-11ene or the two-component combination of DAL-11ene and EDAB. Using DAL-11ene-amine as PI, the prepared polymer films exhibit excellent UV-blocking property. With only 0.5 wt% addition of DAL-11ene-amine, nearly 100% of UVB + UVC and the most of UVA can be blocked by the films. Moreover, DAL-11ene-amine exhibits higher migration stability and biosafety because it can be covalently linked into polymer cross-linking networks. The results indicate that DAL-11ene-amine has great application potentials in preparing environmentally friendly UV-blocking films and biosafety coatings.

Interfacial AIE for Orthogonal Integration of Holographic and Fluorescent Dual-Thermosensitive Images.

Orthogonal integration of thermosensitive images is of vital significance for advanced anticounterfeiting, which however remains formidably challenging due to the trade‐off that facile thermoresponse needs easy molecular motion while robust imaging requires molecular restriction. Herein, a viable approach is demonstrated to tackle the challenge by in situ fixing a predesigned aggregation induced emission luminogen (AIEgen) at the polymer/liquid crystal (LC) interface via precisely controlled interfacial engineering, in which the AIEgen is enriched in LC phases during polymerization induced phase separation and subsequently driven to the interface by the interfacial thiol‐ene click reaction. Crosstalk‐free integration of holographic and fluorescent dual‐thermosensitive images with high sensitivity, high contrast ratio, and robust performance is successfully realized in a single unit, attributed to the simultaneously LC‐facilitated AIEgen molecular motion and polymer‐restricted AIEgen diffusion at the interface. The exciting characteristics of these orthogonally integrated dual images will enable them to prevent illegal replication and thus are expected to be promising for high‐security‐level anticounterfeiting applications.

Metal-free Lewis pairs catalysed synthesis of fluorescently labelled polyester-based amphiphilic polymers for biological imaging

In recent years, the use of fluorescent amphiphilic polymers as the bioimaging agents has achieved significant progress, and promoted the development of the early stage cancer diagnosis and treatment. In this study, a serials of novel nitrobenzoxadiazole (NBD) fluorophore-functionalized polyester-based amphiphilic polymers were designed and synthesized via a two-step process: a hydrophobic polyester backbone was synthesized first by ring-opening alternating copolymerization (ROAC) of phthalic anhydride (PA) and allyl glycidyl ether (AGE) monomers using NBD-OH fluorophore as the initiator and metal-free Lewis pairs as the catalyst; then hydrophilic modified by three different hydrophilic pendants, PEG-SH, mercaptoacetic acid and mono-6-thio-β-cyclodextrin, through thiol-ene click reaction. Notably, directly using fluorophore as the initiator to initiate the ROAC of cyclic anhydrides and epoxides has never been reported. The influence of the feed ratio, type of Lewis pair and reaction temperature upon the polymerization performance were presented and the quantitative introduction of NBD and three kinds of hydrophilic pendants were described in detail as well. Due to the amphiphilic properties, these polymers could facilely self-assemble into fluorescent polymeric nanoparticles, which were characterized by a series of characterization techniques including surface tensiometer, dynamic light scattering (DLS), transmission electronic microscopy (TEM), and fluorescence spectroscopy. These fluorescent polymeric nanoparticles with diameters of tens or hundreds of nanometers showed good particle stability and good fluorescence performance in aqueous solution. The biocompatibility of these fluorescent polymeric nanoparticles was also excellent. In fact, the biological imaging of A549 cells could be realized successfully in the presence of the fluorescent polymeric nanoparticles. This work provides a new strategy and may inspire new approaches to the design and preparation of the biocompatible fluorescent amphiphilic polymers which could be used as the potential biological imaging agents in basic life science research and clinical applications.

Multifunctional superhydrophobic self-cleaning cotton fabrics with oil-water separation and dye degradation via thiol-ene click reaction

• Fluorine-free superhydrophobic and self-cleaning cotton fabric was fabricated. • The modified cotton fabric was tolerant towards different harsh conditions. • The prepared fabric performed great oil–water separation and MB photodegradation. • The separation efficiency was above 99.8% with 6000 L·m −2 ·h −1 after 20 cycles. • The MB photodegradation was above 97% after 5 cycles. Wastewater treatment is a process of significant socio-environmental implications, constantly calling for effective methods towards higher sustainability. In this work, an environment-friendly fluorine-free modified cotton fabric (C-S-TiO 2 cotton fabric) was successfully prepared by the combination of in-situ growth of TiO 2 and hydrophobic modification with octadecyl methacrylate (ODMA) by thiol-ene click reaction. The prepared cotton fabric showed superhydrophobicity/superoleophilicity (water contact angle≈156.2°), self-cleaning property and an ultra-high separation efficiency (>99.90 %) for different kinds of oil–water mixtures with the flux up to 6800 L m −2 h −1 . It was found that the achieved oil separation efficiency was above 99.80 % after 20 cycles. Besides, the C-S-TiO 2 cotton fabric demonstrated an excellent photocatalytic degradation rate for methyl blue (MB) (98.0 %) and the degradation rate was still above 97.0 % after 5 cycles. Importantly, the C-S-TiO 2 cotton fabric was tolerant towards different harsh environments conditioned by acidic solution, alkaline solution, salt solution, and organic solvent. Herein, C-S-TiO 2 cotton fabric was regarded as a promising material for complex wastewater treatment.

Controllability on topological structures and properties of hyperbranched epoxy resins

Hyperbranched epoxy resin (HERs) have attracted increasing attention from scientists and engineers, due to their excellent functionalities in homogenously reinforcing and toughening diglycidyl ether of bisphenol-A (DGEBA) without phase separation. However, it remains a great challenge to control the topological structures of HERs and to discover the effect of microstructure on the properties of epoxy resins. Here, we report the synthesis of NP skeleton epoxy hyperbranched polymer (NMHEP-n) with a controllable degree of branching (DB) and topological structures by a thiol-ene click reaction. The DB of NMHEP-n can be tuned readily with a ratio of designed branched and linear monomers from 0 to 1.0, which can determine the topological structure from linear rod-like chains to ellipsoidal, further to spherical molecular chains. With the increase of DB from 0 to 1.0, a root-mean-square z-average radius of gyration (Rg), hydrodynamic radius (Rh) and shape factor (ρ = Rg/Rh) decrease, being an agreement with the variation from linear to spherical shape. Performance of NMHEP-n/DGEBA composites, including cold resistance, tensile, flexural, and impact strengths, are significantly improved with an increase in DB and content, and the maximum value appears at 12 wt% NMHEP-0.5 in composites. The simultaneous improvement on various properties is attributed to a homogeneous reinforcing and toughening mechanism, which can be rationalized and substantiated by DMA, AFM, SEM, and Raman techniques. These results render an applicable approach to prepare high-performance thermosets and composites.

Pd–Ni bimetallic catalyst supported on dendrimer-functionalized magnetic graphene oxide for efficient catalytic Suzuki-Miyaura coupling reaction

A novel type of dendritic structure was grown on the magnetic graphene oxide nanocomposite surface through thiol-ene click reaction. The resulting nanocomposite was utilized as a support for immobilizing Pd–Ni bimetallic nanoparticles, which were employed in catalytic Suzuki-Miyaura coupling reaction. Transmission electron microscopy and X-ray diffraction analyses confirmed the small size and high dispersity of Pd–Ni nanoparticles. The catalyst efficiently promoted the Suzuki-Miyaura reaction of various aryl bromides and chlorides with arylboronic acids, with excellent yields under mild conditions. The combination of Pd and Ni nanoparticles together with dendritic structure of the catalyst ultimately resulted in the excellent catalytic activity. Not only the existence of dendrimer with high cavities provided the fast adsorption of reactants, but also the synergistic effect between two metals greatly increased the catalytic activity. More importantly, the introduction of Ni significantly increased the catalyst cost-effective. By magnetic separation of the catalyst, it could be retrieved for five times with no remarkable change of activity.

Polycaprolactone strengthening keratin/bioactive glass composite scaffolds with double cross-linking networks for potential application in bone repair

In this study, we aimed at constructing polycaprolactone (PCL) reinforced keratin/bioactive glass composite scaffolds with a double cross-linking network structure for potential bone repair application. Thus, the PCL-keratin-BG composite scaffold was prepared by using keratin extracted from wool as main organic component and bioactive glass (BG) as main inorganic component, through both cross-linking systems, such as the thiol-ene click reaction between abundant sulfhydryl groups of keratin and the unsaturated double bond of 3-methacryloxy propyltrimethoxy silane (MPTS), and the amino-epoxy reaction between amino groups of keratin and the epoxy group in (3-glycidoxymethyl) methyldiethoxysilane (GPTMS) molecule, along with introduction of PCL as a reinforcing agent. The success of the thiol-ene reaction was verified by the FTIR and 1H-NMR analyses. And the structure of keratin-BG and PCL-keratin-BG composite scaffolds were studied and compared by the FTIR and XRD characterization, which indicated the successful preparation of the PCL-keratin-BG composite scaffold. In addition, the SEM observation, and contact angle and water absorption rate measurements demonstrated that the PCL-keratin-BG composite scaffold has interconnected porous structure, appropriate pore size and good hydrophilicity, which is helpful to cell adhesion, differentiation and proliferation. Importantly, compression experiments showed that, when compared with the keratin-BG composite scaffold, the PCL-keratin-BG composite scaffold increased greatly from 0.91 ± 0.06 MPa and 7.25 ± 1.7 MPa to 1.58 ± 0.21 MPa and 14.14 ± 1.95 MPa, respectively, which suggesting the strong reinforcement of polycaprolactone. In addition, the biomineralization experiment and MTT assay indicated that the PCL-keratin-BG scaffold has good mineralization ability and no-cytotoxicity, which can promote cell adhesion, proliferation and growth. Therefore, the results suggested that the PCL-keratin-BG composite scaffold has the potential as a candidate for application in bone regeneration field.Graphical

Thiol-Ene Coupling of High Oleic Sunflower Oil towards Application in the Modification of Flexible Polyurethane Foams.

High oleic sunflower oil-based polyol was obtained by thiol-ene coupling and applied in the preparation of flexible polyurethane foams. The photochemically initiated thiol-ene click reaction was carried out under UV irradiation using 2-mercaptoethanol. Bio-based polyol with hydroxyl value of 201.4 mg KOH/g was used as 30 wt% substituent of petrochemical polyether polyol in the formulations of flexible foams. Both reference foams, as well as foams modified with bio-based polyol, were formulated to have various isocyanate indices (0.85, 0.95, 1.05). Flexible foams were compared in terms of their thermomechanical properties and analyzed using FT-IR and SEM microscopy. Modification with bio-based polyol resulted in foams with superior compression properties, higher support factor, and lower resilience than reference foams. TGA and FT-IR curves confirmed the presence of urethane/urea and ether linkages in the polyurethane matrix. Moreover, double glass transition temperature corresponding to soft and hard segments of polyurethane was observed by DSC proving the phase-separated morphology.