A vanillin-based tetraene monomer (TVE) was synthesized from renewable vanillin via sequential Williamson etherification, followed by atom-economic Claisen rearrangement and Tishchenko condensation. UV-thermal thiol-ene polymerization of TVE yielded a bio-based, cross-linked polyester with tunable thermomechanical properties, high transparency, and UV-blocking capability.

Dynamic polymer networks bridge the gap between traditional thermoplastics and thermosets, representing an avenue toward sustainable polymer synthesis. In this study, we utilize photoinitiated thiol-ene click chemistry to synthesize dynamic polymer networks through incorporating a series of bifunctional silyl ether alkene cross-linkers in the presence of catalytic p-toluene sulfonic acid. We demonstrate that the viscoelastic properties of the material, represented by its stress relaxation time constant, can be manipulated by up to 3 orders of magnitude by simple modifications in catalyst loading, amount of silyl ether cross-linker present, and/or dynamic cross-linker length. Our results show that a nonmonotonic relationship exists between stress relaxation kinetics and cross-linker length. Two representative networks were chosen to illustrate reprocessability under mild temperature conditions. These networks exhibited no loss of mechanical integrity after three reprocessing cycles. The networks can also be fully degraded in the presence of an excess of an acid catalyst.

Microfluidic devices have proven to be a valuable innovation in medical and biological research, offering a fast and efficient platform for testing. Among the materials used for constructing microfluidic channels, off-stoichiometry thiol-ene (OSTE) polymers are especially promising due to their ease of fabrication and lower small-molecule absorption compared to the current gold-standard material, polydimethylsiloxane (PDMS). However, some studies have indicated that there are challenges with binding molecules to the surface thiol groups as they are easily oxidized in air. In this study, a novel linker was synthesized and evaluated for its performance at binding proteins to the surface of OSTE polymer, using a custom-built spectroscopic measurement system. In addition, the results obtained were compared to regular enzyme-linked immunosorbent assay (ELISA) plates and performance of the linker in functionalized microfluidic chips was investigated. Our results indicate that the synthesized linker binds proteins to the OSTE surface and can offer a similar performance to ELISA plates in protein concentration tests highlighting its potential for use in microfluidic chip functionalization.

The spatial and temporal control of material properties at a distance has yielded many unique innovations including photo-patterning, 3D-printing, and architected material design. To date, most of these innovations have relied on light, heat, sound, or electric current as stimuli for controlling the material properties. Here, we demonstrate that an electric field can induce chemical reactions and subsequent polymerization in composites via piezoelectrically-mediated transduction. The response to an electric field rather than through direct contact with an electrode is mediated by a nanoparticle transducer, i.e., piezoelectric ZnO, which mediates reactions between thiol and alkene monomers, resulting in tunable moduli as a function of voltage, time, and the frequency of the applied AC power. The reactivity of the mixture and the modulus of a naïve material containing these elements can be programmed based on the distribution of the electric field strength. This programmability results in multi-stiffness gels. Additionally, the system can be adjusted for the formation of an electro-adhesive. This simple and generalizable design opens avenues for facile application in adaptive damping and variable-rigidity materials, adhesive, soft robotics, and potentially tissue engineering.

The use of two wavelengths to activate different photoreactions in a resin system has recently attracted much attention in the scientific community. Here, wavelength orthogonal photochemistry was used to spatially control the curing kinetics of the thiol-ene photopolymerization reaction. Antagonistic photochemical control is successfully applied to thiol-ene polymerization. In the investigated resin (pentaerythritol-tetrakis(3-mercaptopropionat); PETMP and triallyl-triazine-2,4,6(1H,3H,5H)-trione; TATO) system, radical curing is activated by a type II photoinitiator at 450 nm, while light at 365 nm is used to photorelease a base, resulting in an inhibition of the curing reaction. The antagonistic nature of these photoreactions is demonstrated in laser writing with minimum feature sizes below 0.5 µm as well as in grey scale patterning experiments. Spatially controlled inhibition and retardation of the thiol-ene curing reaction on a sub-micron scale have potential applications in advanced large area lithography, e.g. interference lithography.

Investigation on the highly fluorescent IRMOF-3/thiol-ene polymer and its ligand-based composite with 76 % quantum yield

Abstract Porous polymer networks were synthesized via thiol-ene photo-polymerization using a naturally occurring terpene, myrcene and the multifunctional thiol, trimethylolpropane tris(3-mercaptopropionate). A highly porous structure (up to 80% porosity) was achieved by polymerizing the monomeric phase of high internal phase emulsions (HIPEs), composed of myrcene and trimethylolpropane tris(3-mercaptopropionate) in the presence of ethylene glycol dimethacrylate, which facilitated the formation of polyHIPE materials. Myrcene was incorporated in concentrations ranging from 9 to 40 mol%, and its content was found to significantly influence the resulting polymer morphology. Depending on the formulation, both bicontinuous-like and open-cell polyHIPE morphologies were obtained. In addition to myrcene content, the thiol-to-alkene functional group ratio (1:1 ratio of thiol to alkene groups, as well as formulations with an excess of alkene functionalities relative to thiols). Graphical abstract

In vivo three-dimensional (3D) bioprinting is a promising strategy that can enable personalized organ repair with minimal injury. The current in vivo 3D bioprinting based on upconversion nanoparticles (UCNPs) mediating near-infrared (NIR) light curing is still limited by the low hydrogel cross-linking efficiency. Herein, we introduced a bioink system that allows enhanced NIR light curing by utilizing thiol-ene cross-linkable polymers and photoinitiator-modified UCNPs@LAP nano initiator. The norbornene functionalized hyaluronic acid (NorHA) and thiolated gelatin (GelSH) were first synthesized to prepare the thiol-ene polymer solution. Compared to radical cross-linkable gelatin methacryloyl (GelMA), the NorHA/GelSH exhibited much higher reactivity under weak photoinitiating conditions. With the addition of surface-modified UCNPs@LAP nano initiator, the bioinks showed improved NIR curing performances, which is beneficial to reduce potential thermal damage. Furthermore, in vitro evaluation showed that the NIR light-cured 3D scaffolds preserved excellent bioactivity, suggesting that the hybrid bioink holds great promise to serve as a candidate for in vivo 3D bioprinting.

The development of polymers from renewable resources is a promising approach to reduce reliance on petrochemicals. In addition, depolymerization is attracting significant attention for the breakdown of polymers at their end-of-life or to achieve specific stimuli-responsive functions. However, the design of polymers incorporating both of these features remains a challenge. Herein, we report a new class of self-immolative polymers based on lignin-derived aldehydes via a simple thiol-ene polymerization. These self-immolative polymers undergo cascade degradation in response to specific stimuli through alternating 1,6-elimination and cyclization reactions. The two methoxy substituents on the syringaldehyde monomer accelerated the desired depolymerization reaction, while enhancing stability against undesired backbone hydrolysis. Moreover, diverse responsive end-caps could be introduced through post-polymerization functionalization from a single polymer precursor.

Abstract Limonene, a renewable material derived from citrus fruit peels, can be used as monomer in thiol-ene polymerization with dithiols and tetrathiols to form linear or crosslinked polymers, respectively. The effect of using a thermal- or photoinitiator on polymer properties was evaluated, with the photoinitiator significantly increasing the conversion of the internal unsaturation of limonene with 1,4-butanedithiol (>90%), resulting in higher molecular weights (9,000 g/mol). With pentaerythritiol tetrakis(3-mercaptopropionate), the gel content remained below 15% in thermally initiated reactions (28,000 g/mol) but increased to above 90% in photoinitiated ones. Finally, combining both thiols resulted in an intermediate molecular weight (~13,000 g/mol) for thermal initiation, and a gel content of about 85% for the photoinitiated ones. Thus, thiol-ene reactions stand out as an effective approach for the synthesis of polymers from limonene, with molecular weight and gel content being fine-tuned by the type/ amount of initiator, and by the combination of di- and tetrathiol.

We assembled metal-organic cages by combining rare-earth metals with an alkene-terminated ligand (L), allowing for subsequent thiol-ene polymerization of the cages to yield rare-earth-binding polymer networks. Mixed-metal self-assembly experiments with ligand L show that the size ratio of the respective rare-earth metals dictates the metal composition of the cages.

Compositions of ethylene glycol dicyclopentenyl ether methacrylate (EGDEMA), a vegetable oil based alkyl methacrylate (C13MA), and furfuryl methacrylate (FMA) were terpolymerized for dual-crosslinked networks with tailored mechanical and thermal properties. Specifically, initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) afforded materials with tailored glass transition temperature (T g) and incorporation of furan and norbornene functionalities within a single chain. The terpolymer with high furan and norbornene functionality (Ter2: F FMA = 0.42, F EGDEMA = 0.46, F C13MA = 0.12) is crosslinked to form single-crosslinked reversible networks with 1,1'-(methylenedi-4,1-phenylene)bismaleimide (BM) via Diels-Alder (DA) chemistry and dual-crosslinked networks incorporating additional non-reversible thiol-ene crosslinks. The reactions were photo-initiated using 254 nm UV light with BM : FMA molar ratios of 0.1 and 0.2 for both systems. FTIR analyses for crosslinked Ter2 samples confirmed the successful formation of DA and thiol-ene adducts, while DSC confirmed the reversibility of the DA reaction. A terpolymer with higher C13MA composition (Ter3: F C13MA = 0.75, F FMA = 0.17, F EGDEMA = 0.08) was similarly crosslinked in single and dual crosslinked networks with BM : FMA of 0.1 and 0.2. Crosslinking efficiency was evaluated for both single and dual crosslinked networks with a BM : FMA = 0.1 by comparing thermal and UV curing methods, with UV curing proving more effective for dual-crosslinked systems, leading to increased gel content (71% with UV compared to 61% thermally) and improved material properties. FTIR and DSC results confirmed the formation of the DA adducts and the reversibility of the DA reaction. The terpolymers were further analyzed for adhesive applications through rheological testing. These studies demonstrated that the incorporation of thiol-ene crosslinking alongside Diels-Alder crosslinking offers a balanced combination of reversible and permanent bonds, resulting in materials with enhanced mechanical strength, thermal stability, and functional versatility that are suitable for applications such as recyclable adhesives.

Surface modification is essential in microfluidic applications due to the inherent hydrophobicity of polymers, which can lead to biofouling and reagent denaturation. Despite the development, challenges such as hydrophobic molecule absorption and limitations in scaling are still present. Off-stoichiometry thiol-ene (OSTE) materials have emerged as a promising alternative, offering advantages like rapid prototyping, minimal hydrophobic absorption, and customizable surface chemistries. While the thiol-ene polymerization mechanism is well understood, the fundamental understanding of thiol group binding on OSTE surfaces remains limited. Existing techniques to analyze surface groups lack the capability to confirm the stable presence of thiol groups on the surface. In our study, using Raman and X-ray photoelectron spectroscopy techniques, we investigated a potential method for enhancing the surface properties of OSTE polymer-the attachment of novel linkers to the surface. We have demonstrated our synthesized compound efficiency by binding gold nanoparticles to the OSTE surface. Our findings indicate that chemical reactions involving double bonds with the material surface hold the most potential for effective surface modification for gold binding.

Luminescent solar concentrators (LSCs) are effective large-area sunlight collectors that use solar cells to convert focused sunlight into electricity based on the emissive fluorophores. However, the development of high-performance LSCs still remains a challenge. In this work, LSCs are fabricated by incorporating CdSe/ZnS core-shell quantum dots (QDs) and Au nanoparticles (NPs) into the off-stoichiometric thiol-ene (OSTE) polymer. The light absorption efficiency and photoluminescence (PL) intensity of CdSe/ZnS QDs are significantly enhanced by the localized surface plasmon resonance (LSPR) effect of Au NPs. When the concentration of Au NPs is 2 ppm, the maximal internal quantum efficiency (ηint) and external quantum efficiency (ηext) of CdSe/ZnS LSCs are measured to be 9.90% and 3.85%, respectively. Compared to the control devices, the increases of 1.78-fold in ηint and 2.97-fold in ηext are achieved. In addition, the power conversion efficiency (PCE) and optical efficiency (ηopt) of CdSe/ZnS LSCs show increases of 0.49 times and 0.35 times, respectively. Furthermore, the LSC with 2 ppm Au NPs possesses excellent aesthetic parameters with a color rendering index (CRI) of 92.11 and an average visible transmission (AVT) of 75.02%. Therefore, the optimal concentration of Au NPs will shed light on high-efficiency LSCs with superior aesthetic parameters to meet the demands of practical applications.

Strategies to design multifunctional interfaces for biosensors have been extensively investigated to acquire optimal sensitivity, specificity, and accuracy. However, heterogeneous ingredients in clinical samples inevitably generate background signals, exposing challenges in biosensor performance. Polymer coating has been recognized as a crucial method to functionalize biointerfaces by providing tailored properties that are essential for interacting with biological systems. Herein, we introduce for the first time two oligomeric silatranes, MPS-MPCn and MPS-PEGMACOOHm, which were copolymerized from mercaptopropylsilatrane (MPS) with either zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) or carboxylated poly(ethylene glycol) methacrylate (PEGMACOOH) through thiol-ene polymerization. These oligomeric silatranes were prepared individually and in combinations in acidic and nonacid solvents for deposition on silicon wafers. Afterward, coating properties, including wettability, thickness, and elemental composition, were characterized by contact angle meter, ellipsometer, and X-ray photoelectron spectroscopy (XPS), respectively. Importantly, MPS-MPCn polymers were found to form thin films with high hydrophilicity and superior fouling repulsion to bacteria and protein, while mixed coating involving 70% MPS-PEGMACOOH2.5 and 30% MPS-MPC2.5 exhibited thinnest coating with best wettability among COOH-terminated coatings. Furthermore, the functional COOH group in the coated surfaces was exploited for postmodification with biological molecules via intermediated N-hydroxysuccinimide (NHS) ester group by amine coupling chemistry. Once again, the combination of 70% MPS-PEGMACOOH2.5 and 30% MPS-MPC2.5 provided an ultimate reduction in nonspecific adsorption (NSA) and established a finest signal discrimination through enzyme-linked immunosorbent assay. Consequently, these novel mixed oligomeric silatranes offer a promising approach for the construction of biosensor interfaces with dual functions in both nonspecific binding prevention and conjugation of biomolecules.

Artificially prepared superhydrophobic surfaces towarda self-cleaning“lotus effect” and anticontamination performance havebecome critically important in the past few years. However, most approachesto create the required topology with a hierarchical roughness compriseseveral manufacturing steps of varying practicality. Moreover, thedesired low surface energy is in most cases achieved with fluorinatedmoieties that are currently criticized due to biological and environmentalhazards. In this work, rapidly photocuring but weak thiol–eneresins were reinforced with cellulose nanofibrils (CNFs) to replicatelotus leaves via one-step UV nanoimprint lithography. The CNFs weresurface-modified using countercation exchange of carboxyl groups andgrafting of thiol and methacrylate functionalities. The formulationmethodology resulted in free-flowing, shear-thinning composite resinswithout surfactants or dispersants. The rheological and photo-cross-linkingbehavior of the resins, the thermal stability, the mechanical performance,and the hydrophobicity of the cured composites were characterized.Notably, the surface modifications increased the as received fibrildiameter (1.9 ± 0.6 nm) by 1.6–2.3 nm and raised the fibril–resincompatibility. The resins underwent rapid polymerization and the highthermal stability of thiol–enes was retained. The methacrylatednanofibrils (10 vol %) significantly strengthened the rubbery network,outperforming the neat thiol–ene polymer in terms of hardness(3.4×), reduced modulus (5.8×), and wear resistance (>100×).Moreover, the surface of lotus-texturized composites was superhydrophobicwith a water contact angle of 155°, higher than that of the neatpolymer (147°), and was self-cleaning. These CNF composite resinsare compatible with fast-cure processes such as 3D printing and roll-to-rollprocessing, are exempt of fluorine or any other hydrophobization treatment,and are extremely wear-resistant.

Thiol–acrylate photopolymerization has emerged as a prevalent approach for network formation due to its reaction efficiency, monomer versatility, and simple process. However, the reaction mechanism of network formation and eventual regulation of the network properties remain unclear and challenging. Different from the conventional unimechanism of thiol–acrylate photopolymerization, herein, thiol–acrylate photopolymerization was considered as a binary polymerization between thiol–ene polymerization of thiol and acrylate (TEP) and free radical polymerization of acrylates (FRP). The kinetic behavior of diacrylate and multithiols (dithiol, trithiol, and tetrathiol) was monitored by real-time in situ FTIR and treated with a binary polymerization model. By simulation of the hybrid function and calculation of the hybrid parameters, the binary polymerization revealed that there existed a mutual interaction instead of orthogonal behavior between TEP and FRP. Notably, a significant transition from inhibition to a promotion effect was observed with increasing thiol composition and thiol functionality. Moreover, the physical/mechanical properties of the photo-cross-linked networks could be easily regulated through adjusting the mutual interaction of TEP and FRP. By increasing thiol functionality, the gel content of the formed networks increased, and the uniformity of networks was improved. Consequently, the reaction mechanism of thiol–acrylate polymerization can be perfectly interpreted by binary polymerization, which provides guidance for variable multithiol–diacrylate networks with tunable properties.

Phosphorus-containing polymers find applications as fire retardant additives and biomimicking macromolecules. Herein, a series of polymers are synthesized by thiol-ene polymerization using a novel, high phosphorus content diacrylate monomer (PNDA) and various aliphatic and aromatic dithiols and amines. Depending on the chemical structure of the dithiol, low molecular weight polymers with relatively low or high glass transition temperatures are obtained. Molecular weight can be increased by copolymerizing the dithiols with PNDA in the presence of other more reactive diacrylates or by polymerizing PNDA with amines. Furthermore, polyhydroxyurethanes were synthesized by derivatizing unsaturated phosphoramidates to epoxides and subsequently to cyclic carbonates, which were then reacted with diamines. We also explore the thermal stability of the polymers as well as their application as a fire retardant additive for epoxy resins.

While QDs are typically made of semiconductors, metals at low dimensions also turn to discrete electronic structure. The characteristic transition size from bulk to nanodot is lower, because Fermi level position is at the band middle, while discretization of levels starts from the band edge. Therefore, only for sizes of a metal entity ~ 1 nm a QD-like behavior manifests.Here we show that metal nanoclusters Au16Ag7 of an electrum alloy (gold-silver) with adamantanethiolate ligands possess PL quantum yield of ~ 70% in a thiol-ene polymer matrix [1]. PL is in NIR range with a large Stokes shift. Due to parity-forbidden transition the PL lifetime is in microseconds. These characteristics are similar to silicon QDs, where optical transition is also partly forbidden. Luminescence from Si QDs (5-10 nm size) may also feature high quantum efficiency when a defect-free core with good surface passivation is prepared. We have demonstrated a new synthesis method, which can reduce precursor cost by an order of magnitude from the established HSQ-based technique [2]. Si QDs prepared in this way have near-unity internal and > 50% external (quantum yield) efficiency with a large Stokes shift. In both nanomaterials the re-absorption is suppressed, which is of value for several applications.One such application is a semi-transparent photovoltaics for glazing in building-integration. It is based on a luminescent solar concentrator concept, where high efficiency and a large Stokes shift are necessary requirements for nanophosphors. In this configuration absorbed solar light is re-emitted and a large fraction of it is guided by total internal reflection to the edges for collection by standard solar cells. As a proof-of-concept we fabricated 20x20 cm2 prototypes, where Si QD-doped polymer layer is sandwiched between glass plates in a triplex geometry. Such “solar windows” feature high transparency (>80%), low haze (<3%), high color rendering index (~ 88) and, at the same time, deliver up to 0.6 W of electrical peak power under one sun [3]. Original measurement techniques were developed to characterize large-area devices [4,5].

Improving the removal rate of bisphenol A and Cu2+ from water using P/N coexisting β-cyclodextrin-based adsorbents by enhancing adsorbents-pollutants interactions