Biobased Aromatic-Aliphatic Polyols from Cardanol by Photochemical Thiol-ene Reaction

Biobased aromatic-aliphatic polyols were previously synthesized from a thermal thiol-ene reaction of propoxylated cardanol with 2-mercaptoethanol(ME)in the presence of azobisisobutyronitrile(AIBN)as a radical initiator.Cardanol used for this purpose was obtained as a dark-brown liquid(Gardner Color Reference^18).The photochemical thiol-ene reaction can also be used to prepare aromatic-aliphatic polyols by employing cardanol.Via the photochemical thiol-ene reaction,2-mercaptoethanol was added successfully to C=C double bond of cardanol,suggesting that phenolic group may not play an inhibitory role in the radical thiol-ene reaction.However,we preferred to alkoxylate the phenolic hydroxyl group of cardanol,which is much more reactive with isocyanates than phenolic hydroxyls,to generate a new aliphatic hydroxyl group.Furthermore,the functionality of polyols was also improved by two methods:1)using 1-thio-glycerol instead of 2-mercaptoethanol and 2)using alkoxylated cardanol with glycidol(Cardanol-GLY)instead of propoxylated cardanol(Cardanol-PO).These polyols were then used in preparation of rigid polyurethane foams that can be useful in various applications such as insulation of freezers,pipes and storage tanks in food and chemical industries.

Biobased Aromatic-Aliphatic Polyols by Thiol-Ene Reactions of Propoxylated Mercaptanized Cardanol

Aromatic-aliphatic polyols were obtained previously from the thiol-ene reactions of propoxylated cardanol with hydroxyalkyl mercaptans;these aromatic-aliphatic polyols were then utilized in the preparation of rigid polyurethane foams with excellent properties.The current work describes a variant of cardanol polyol synthesis by thiol-ene reactions in three steps.The first step is propoxylation of cardanol by reacting cardanol with propylene oxide;the second step is mercaptanization of propoxylated cardanol by reacting double bonds with hydrogen sulfide;and the third step involves the addition of the thiol groups of mercaptanized propoxylated cardanol to the double bonds of allyl alcohol,glycerol-1-allyl ether,and trimethylolpropane allyl ether.Thus,obtained polyols were characterized by standard analytical methods.Rigid polyurethane foams prepared from these polyols show promising physical-mechanical properties.The rigid polyurethane foams can be used for various applications such as thermo-insulation of freezers,storage tanks and pipes for food and chemical industries,wood substitutes and flotation materials.

Biobased Aromatic-Aliphatic Polyols from Cardanol by Thermal Thiol-Ene Reaction

Cardanol is a natural phenol which is obtained from high vacuum distillation of cashew nut shell liquid.It contains a hydrocarbon chain of 15 carbon atoms in the meta position,either with one,two or three nonconjugated double bonds.This article describes thermal thiol-ene reaction to synthesize new cardanol-based polyols for polyurethanes with aromatic-aliphatic structure.Phenolic hydroxyl group was blocked by alkoxylation and 2-mercaptoethanol was added to the double bonds of propoxylated cardanol.The resultant product is a mixture of polyols that may contain one,two,three or four hydroxyl groups,as a function of the number of double bonds reacted with 2-mercaptoethanol.Similar polyols,but with much higher functionality,were also synthesized from condensation of cardanol-based novolacs with formaldehyde.These cardanolbased polyols were further utilized to prepare rigid polyurethane foams(PUs)with excellent physical and mechanical properties,useful for various applications in chemical and food industries.

Synthesis of Novel Hexathiolated Squalene and Its Thiol-Ene Photopolymerization with Unsaturated Monomers

In this work is described the synthesis of a multifunctional thiolated squalene. Thiol-ene coupling reactions were employed to functionalize the six double bonds of squalene, using thiolacetic acid. Hydrolysis of the resulting thioacetates, rendered the corresponding hexathiolated squalene SQ6SH. This compound was further photopolymerized separately with triallyl cyanurate, pentaerythritol triacrylate and diethyleneglycol divinyl ether. Real Time FTIR kinetics revealed that homopolymerization of the ene monomers took place in addition to the thiol-ene photopolymerization. Flexible films were obtained when SQ6SH was photopolymerized in bulk with the above mentioned unsaturated monomers.

Effects of Molar Ratios of Thiol-Ene Monomers on the Morphology and Electro-Optical Properties of Polymer Dispersed Liquid Crystal Films

We synthesized tetrafunctional allyl ether monomer (4-AE) and investigated the effects of the different molar ratios of trimethylolpropane tris-(3-mercaptopropionate) (3-SH) to 4-AE on the photopolymerization behavior, morphology, and electro-optical properties of thiol-ene-based PDLC films. Photo-DSC and DSC analyses revealed that the PDLC sample containing 45 wt% 3-SH and 45 wt% 4-AE gave the highest exotherm, the fastest photocure rate, and the highest Tg due to the matched stoichiometry. Morphological observations and electro-optical measurements showed that the PDLC sample with the matched molar ratio gave the smallest LC droplet size, the highest threshold, driving voltages, and lowest saturation transmittance because the orientation of LC molecules got difficulty in small droplets. The stoichiometric ratios of 3-SH to 4-AE played an important role in controlling the photocure rate, phase separation rate, microstructures of LC droplets, and electro-optical properties of thiol-ene-based PDLC systems.

Thiol-ene crosslinked cellulose-based gel polymer electrolyte with good structural integrity for high cycling performance lithium-metal battery

Gel polymer electrolytes(GPEs) are considered to be one most promising alternative to liquid electrolytes due to their suitability for creating safe and durable solid-state lithium-metal batteries. However, the mechanical properties of GPEs usually deteriorate dramatically when polymer matrices are plasticized by a liquid electrolyte, which leads to significant loss of battery performance. Therefore, the long-term structural integrity and good mechanical strength are critical characteristics of GPEs designed for highperformance batteries. Here, an ecologically compatible cellulose-based GPE with a crosslinked structure is synthesized via a facile and effective thiol-ene click chemistry method. The prepared thiol-ene crosslinked GPE possesses enhanced mechanical strength(10.95 MPa) and rigid structure, which enabled us to fabricate Li Fe PO_(4)|Li batteries with ultra-long cycling performance. The capacity retention of the crosslinked cellulose-based GPE can be up to 84% at 0.5 C, even after 350 cycles, which is considerably higher than that of non-crosslinked GPE for which rapid decline in capacity occurs after 200 cycles. In addition, a GPE preparation method described in this work compares favorably well with existing commercial electrolytes for lithium metal batteries.

Thiol-ene conjugation of a VEGF peptide to electrospun scaffolds for potential applications in angiogenesis

Vascular endothelial growth factor(VEGF)plays a vital role in promoting attachment and proliferation of endothelial cells,and induces angiogenesis.In recent years,much research has been conducted on the functionalization of tissue engineering scaffolds with VEGF or a VEGF-mimetic peptide to promote angiogenesis.However,most chemical reactions are nonspecific and require organic solvents,which can compromise control over functionalization and alter peptide/protein activity.An attractive alternative is the fabrication of functionalizable electrospun fibers,which can overcome these hurdles.In this study,we used thiol-ene chemistry for the conjugation of a VEGF-mimetic peptide to the surface of poly(ε-caprolactone)(PCL)fibrous scaffolds with varying amounts of a functional PCL-diacrylate(PCL-DA)polymer.30%PCL-DA was selected due to homogeneous fiber morphology.A VEGF-mimetic peptide was then immobilized on PCL-DA fibrous scaffolds by a light-initiated thiol-ene reaction.7-Mercapto-4-methylcoumarin,RGD-FITC peptide and VEGF-TAMRA mimetic peptide were used to validate the thiol-ene reaction on the fibrous scaffolds.Tensile strength and elastic modulus of the 30%PCL-DA fibrous scaffolds were significantly increased after the reaction.Conjugation of the 30%PCL-DA fibrous scaffolds with the VEGF peptide increased the surface water wettability of the scaffolds.Patterned structures could be obtained after using a photomask on the fibrous film.Moreover,in vitro studies indicated that scaffolds functionalized with the VEGF-mimetic peptide were able to induce phosphorylation of the VEGF receptor and enhanced HUVECs survival,proliferation and adhesion.A chick chorioallantoic membrane(CAM)assay further indicated that the VEGF peptide functionalized scaffolds were able to promote angiogenesis in vivo.These results show that scaffold functionalization can be controlled via a simple polymer mixing approach,and that the functionalized VEGF peptide-scaffolds have potential for vascular tissue regeneration.

Generating Microstructures with Highly Variable Mechanical Performance using Two-Photon Lithography and Thiol-ene Photopolymerization

In this study,we investigate the effect of the exposure dose on the mechanical property of the photoresins generated with acrylate self-polymerization and thiol-ene polymerization.The results indicate that the mechanical performance of the thiol-ene photoresin is highly depended on the exposure dose during the solidification process.With 350-fold exposure dose change,the stiffness of the thiol-ene photoresin reached more that 700-fold change compare to 14-fold of the acrylate photoresin.We developed a TPL photoresist based on our results and show the capability to fabricate microstrucutres with high resolution and variable mechanical performances using this method.

Off-stoichiometry improves the photostructuring of thiol-enes through diffusion-induced monomer depletion

Thiol–enes are a group of alternating copolymers with highly ordered networks and are used in a wide range of applications.Here,“click”chemistry photostructuring in off-stoichiometric thiol–enes is shown to induce microscale polymeric compositional gradients due to species diffusion between non-illuminated and illuminated regions,creating two narrow zones with distinct compositions on either side of the photomask feature boundary:a densely cross-linked zone in the illuminated region and a zone with an unpolymerized highly off-stoichiometric monomer composition in the non-illuminated region.Using confocal Raman microscopy,it is here explained how species diffusion causes such intricate compositional gradients in the polymer and how offstoichiometry results in improved image transfer accuracy in thiol–ene photostructuring.Furthermore,increasing the functional group off-stoichiometry and decreasing the photomask feature size is shown to amplify the induced gradients,which potentially leads to a new methodology for microstructuring.

Fast photocurable thiol-ene elastomers with tunable biodegradability,mechanical and surface properties enhance myoblast differentiation and contractile function

Biodegradable elastomers are important emerging biomaterials for biomedical applications,particularly in the area of soft-tissue engineering in which scaffolds need to match the physicochemical properties of native tissues.Here,we report novel fast photocurable elastomers with readily tunable mechanical properties,surface wettability,and degradability.These elastomers are prepared by a 5-min UV-irradiation of thiol-ene reaction systems of glycerol tripentenoate(GTP;a triene)or the combination of GTP and 4-pentenyl 4-pentenoate(PP;a diene)with a carefully chosen series of di-or tri-thiols.In the subsequent application study,these elastomers were found to be capable of overcoming delamination of myotubes,a technical bottleneck limiting the in vitro growth of mature functional myofibers.The glycerol-based elastomers supported the proliferation of mouse and human myoblasts,as well as myogenic differentiation into contractile myotubes.More notably,while beating mouse myotubes detached from conventional tissue culture plates,they remain adherent on the elastomer surface.The results suggest that these elastomers as novel biomaterials may provide a promising platform for engineering functional soft tissues with potential applications in regenerative medicine or pharmacological testing.

Functionalized Polyphosphoester via Living Ring-opening Polymerization and Photochemical Thiol-ene Click Reaction

Poly(ethylene phosphonate)was synthesized via the living ring-opening polymerization of cyclic phos-phonate monomer catalyzed by organocatalyst.The pendant vinyl ftmctionalities were employed to perform the pho-tochemical click reactions wi&tMols.We demonstrated that both small thiol molecules and macromolecular thiols could be efficiently coupled into the PPE side chains,enabling the rapid and efficient functionalization of polyphos-phoesters(PPE).

Eutectic Solution Enables Powerful Click Reaction for In-Situ Construction of Advanced Gel Electrolytes

Thiol-ene click reaction is an intriguing strategy for preparing polymer electrolytes due to its high activity,atom economy and less side reaction.However,the explosive reaction rate and the use of non-electrolytic amine catalyst hamper its application in in-situ batteries.Herein,a nitrogen-containing eutectic solution is designed as both the catalyst of the thiol-ene reaction and the plasticizer to in-situ synthesize the gel polymer electrolytes,realizing a mild in-situ gelation process and the preparation of high-performance gel electrolytes.The obtained gel polymer electrolytes exhibit a high ionic conductivity of 4×10^(−4)S cm^(−1)and lithium-ion transference number(t_(Li)^(+))of 0.51 at 60°C.The as-assembled Li/LiFePO_(4)(LFP)cell delivers a high initial discharge capacity of 155.9 mAh g^(-1),and a favorable cycling stability with the capacity retention of 82%after 800 cycles at 1 C is also obtained.In addition,this eutectic solution significantly improves the rate performance of the LFP cell with high specific capacity of 141.5 and 126.8 mAh g^(-1)at 5 C and 10 C,respectively,and the cell can steadily work at various charge–discharge rate for 200 cycles.This powerful and efficient strategy may provide a novel way for in-situ preparing gel polymer electrolytes with desirable comprehensive performances.

点击化学合成具有聚集诱导荧光特性的双响应性聚合物凝胶

本文合成了巯基功能化的四苯基乙烯并利用thiol-ene点击化学合成得到聚合物凝胶.基于四苯基乙烯的聚集诱导发光特性,聚合物凝胶的合成过程可以通过四苯基乙烯荧光发射性能的变化进行监测.此外,由于凝胶的还原和酸性环境响应性,在二硫苏糖醇和三氟乙酸存在下,凝胶的荧光发射会被猝灭,这种双重刺激响应性使其在荧光传感成像、癌症诊断和自愈合材料方面具有潜在的应用价值.

新型聚醚基三硅氧烷表面活性剂的制备及表面活性

以巯丙基三硅氧烷与聚乙二醇烯丙基甲基醚经thiol-ene反应合成了新型聚醚基三硅氧烷表面活性剂,并对其结构进行了FT-IR和~1H NMR表征,通过表面张力的测定考察了其表面活性。结果表明,该法可以高效合成高纯度的聚醚基三硅氧烷表面活性剂,该表面活性剂能将水的表面张力降低至21～23 mN/m,具有优良的表面活性。

Tetra-alkylsulfonate functionalized poly(aryl ether) membranes with nanosized hydrophilic channels for efficient proton conduction

The microstructure of polymer electrolyte membranes plays a key role in ion conductivity and water transport.Herein,fluorinated poly(aryl ether)s with tetra-alkylsulfonate side chains(SFPAEs)have been successfully synthesized from the copolymerization of a newly developed tetra-allyl-containing bisphenol(TABP)monomer,followed by the thiol-ene addition with sodium 3-mercapto-1-propanesulfonate to attach the ionic groups at the end of the flexible chains.Being the first of its kind,the densely distributed and lengthy alkylsulfonate group possesses the benefit of ease to self-assemble into hydrophilic domains during membrane preparation via solution casting.Indeed,the TEM characterizations revealed that distinct hydrophilic channels of 1-2 nm width had been formed,much larger than those of a home-made control sample where only di-alkylsulfonate side chains were attached.The SFPAE-4-45 with an IECw of 2.0 mmol g^-1 exhibited an enhanced proton conductivity of 143.7 m S cm^-1 at room temperature,which was superior to that of Nafion 212(91.0 m S cm^-1).Furthermore,the oxidative stabilities of SFPAEs were significantly higher than those of non-fluorinated analogs in literature.This study offered a new route to engineering the pendent structure of ionomers for well-defined microscopic morphologies.

New Biobased Polyurethane Materials from Modified Vegetable Oil

Bio-based polyurethanes(PUs)have been occurred a large attention nowadays.It was found to be an alternative to the petrochemical based materials to the fact of their weak environmental influence,availability,good price and biodegradability.In addition,the nature shows several bio-derived compounds as raw materials for the synthesis of polyols,including the vegetable oils,polyphenol,terpene,and other bio-renewable sources.With the aim to develop a new family of biobased polyurethanes(PUs)via vegetable oils,the elaboration of new Jojoba-based PUs was performed by catalyst-free polycondensation reaction of a synthesized Jojoba diol with various diisocyanates such us toluene diisocyanate(TDI)and isophorone diisocyanate(IPDI).All the compounds were characterized by FTIR and NMR spectroscopies,and their properties were determined by gel permeation chromatography,differential scanning calorimetry and thermogravimetric analysis.The obtained results show renewable vegetable oils-based PUs materials can be preparing using a new environmentally ways and giving various good properties performances.

Cardanol-Based Polyurethane Coatings via Click Chemistry:An Eco-friendly Approach

This research work discloses the preparation of polyurethane coatings from cardanol modified using thiolene chemistry,wherein unsaturated long alkyl chain of cardanol was successfully utilized via thiol-ene click reaction to synthesize polyol.For this purpose,cardanol and thioglycerol was reacted in the presence of Irgacure 184(photoinitiator)and 1,8-Diazabicyclo[5.4.0]undec-7-ene(catalyst)and exposed to UV light for 12 h at 80℃.One mole of thioglycerol was successfully added across the double bond of fatty chain of cardanol and confirmed by chemical and spectroscopic analysis.Further,the polyol thus prepared was cured with various polyisocyanates,viz.,N-75(HDI based),L-67/BA(TDI based),Z-4470(IPDI based)and corresponding polyurethane coatings were developed.The coatings were then analyzed for mechanical,chemical,optical,thermal and anticorrosive properties.It was observed that cardanol-based PU coatings exhibited excellent mechanical,chemical and thermal and anticorrosive properties as compared to that of commercial acrylic-PU coatings.

Silicone Elastomer with High Elongation at Break Used in Digital Light Processing 3D Printing

3D printing silicone elastomer has demonstrated great potential in diverse areas such as medical devices,flexible electronics and soft robotics.It is of great value to investigate how to improve the mechanical properties,including tensile strength and elongation at break of printed parts.In this work,a light curing system that can be applied in silicone elastomer 3D printing is explored,which is composed of vinyl terminated polysiloxane as the macromer and thiol containing polysiloxane as the crosslinking agent,and a chain extension reaction is also introduced into this light curing system via the addition of the chain extender dithiol molecules,and a light curing system accompanied with chain extension is designed and realized based on the thiol-ene click reaction mechanism.After reinforced with silica fillers,the obtained light curing system can endow the light curing silicone elastomer with better mechanical properties under the condition of a lower viscosity of the precursor,the tensile strength and elongation at break can reach 525.5 k Pa and 601%,respectively.This light curing system provides a feasible method to solve the contradiction between the viscosity of the precursor and the mechanical properties of the light curing elastomer in the digital light processing(DLP)3D printing field.

Precision Synthesis of End-Functionalized Star Poly(vinyl alcohol)s by RAFT Polymerization and Post-polymerization Modification

Poly(vinyl alcohol)(PVA)has been widely used in industrial and consumer products.In this study,we aimed to address this challenge by synthesizing well-defined multiarm poly(vinyl acetate)(PVAc)through the use of nonhydrolyzable vinyl ethertype multifunctional RAFT agents.The control over molecular weights was achieved by the RAFT process to afford polymers with dominant head-to-head linkages at the terminal.Especially,quantitative end-functionalization of the synthesized PVAc was performed using Michael thiol−ene or disulfide exchange reactions.Consequently,saponification of the PVAc enabled the synthesis of end-functionalized multiarm PVA in an efficient manner.This straightforward approach afforded well-defined functional PVAs,which enable further chemical modification,thus widening the utility of PVA in a range of applications,such as precisely controlled network synthesis and bioconjugation.

Side Chain Engineering of Sulfonated Poly(arylene ether)s for Proton Exchange Membranes

Proton conductivity of proton exchange membranes(PEMs)strongly relies on microscopic morphology,which can be modulated by engineering the distribution of ionic groups.Herein,poly(arylene ether)s with densely distributed allyl functionalities are polymerized from a tetra-allyl bisphenol A monomer.The subsequent thiol-ene addition with sodium 3-mercapto-1-propanesulfonate yields comb-shaped sulfonated fluorinated poly(arylene ether)s(SFPAEs)with ion exchange capacities(lECs)ranging from 1.29 mmol·g^-1 to 1.78 mmol g^-1.These SFPAEs exhibit superior proton conductivity over the whole temperature range,which is attributed to the enhanced hydrophilic/hydrophobic phase separation as evidenced by small angle X-ray scattering characterizations.The SFPAE-4-40 with an IEC of 1.78 mmol·g^-1 shows the largest proton conductivity of 93 mS-crrr1 at room temperature under fully hydrated condition,higher than that of Nafion 212.Furthermore,the vanadium redox flow battery(VRFB)assembled with SFPAE-4-40 separator exhibits higher energy efficiency than the VRFB assembled with Nafion 212.