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The efficient adsorption or catalytic degradation of toxic chemicals is desired to provide effective personal protection in both industrial and possible military situations. The possibility of both chemical warfare agents (CWAs, e.g., VX) and toxic industrial chemicals (TICs, e.g., NH3) being released underscores the need for new materials capable of sequestering and/or decontaminating these chemicals. For this purpose, we developed a new composite material by conjugating an inorganic molecule with nano-sized silica support. Specifically, zirconium (oxo) hydroxy methacrylate (Zr cluster) composed of a Zr6O4(OH)4 node and methacrylate backbones is polymerized on the surface of silica (SiO2) nanoparticles upon UV irradiation, and this composite material is tested for (1) catalytic hydrolysis of a CWA simulant, dimethyl p-nitrophenyl phosphate (DMNP) and (2) adsorption of a TIC, ammonia. The composite material displays superior catalytic performance towards DMNP hydrolysis compared to the "free" Zr cluster, and it also shows greater adsorption capacity for NH3 than the bare silica nanoparticles. The advantage of the low-cost and low-complexity of the synthesis is demonstrated in a notional clothing decontamination scenario, where the Zr-silica composite catalyst is embedded in fabric swatches and evaluated for its adsorption and decontamination capabilities.

Most commercial dressings with moderate to high exudate uptake capacities are mechanically weaker and/or require a secondary dressing. The current research article focuses on the development of hydrogel-based wound dressings combining mechanical strength with high exudate absorption capacities using acrylate-endcapped urethane-based precursors (AUPs). AUPs with varying poly(ethylene glycol) backbone molar masses (10 and 20 kg mol(-1)) and endcap chemistries are successfully synthesized in toluene, subsequently processed into UV-cured hydrogel sheets and are benchmarked against several commercial wound dressings (Hydrosorb, Kaltostat, and Mepilex Ag). The AUP materials show high gel fractions (>90%) together with strong swelling degrees in water, phosphate buffered saline and simulated wound fluid (12.7-19.6 g g(-1)), as well as tunable mechanical properties (e.g., Young's modulus: 0.026-0.061 MPa). The AUPs have significantly (p < 0.05) higher swelling degrees than the tested commercial dressings, while also being mechanically resistant. The elasticity of the synthesized materials leads to an increased resistance against fatigue. The di- and hexa-acrylated AUPs show excellent in vitro biocompatibility against human foreskin fibroblasts, as evidenced by indirect MTS assays and live/dead cell assays. In conclusion, the processed AUP materials demonstrate high potential for wound healing application and can even compete with commercially available dressings.

Over a short period of time, electronic assemblies have been dramatically developed with smaller size and lighter weight and 3D printing plays a crucial role in their future production. However, it is difficult to develop epoxy resins and other thermoset resins for this process because of the polymer's liquid state during processing. This work uses a UV curing technique for making flexible epoxy/multi-walled carbon nanotubes (MWCNTs) composites that are suitable for future 3D printing applications. The synthesized carbazole-coated TiO2 nanoparticles, used as a photosensitizer, were characterized by their photoabsorbance, morphology, and surface property before use. The results indicated that the TiO2 nanoparticles coated with 75 wt% carbazole were appropriate for UV-cured flexible epoxy/MWCNT composites because of its fast cure kinetics after irradiation by a UV light source. The epoxy/MWCNT composites displayed low tensile properties because of the agglomeration of MWCNTs inside the epoxy matrix. In addition, the epoxy/MWCNT composites showed slightly lower thermal expansion with high electrical properties with a large amount of MWCNTs in the epoxy composites.

International audience; In this work, eleven heteroleptic copper complexes were designed and studied as photoinitiators of polymerization in three-component photoinitiating systems in combination with an iodonium salt and an amine. Notably, ten of them exhibited panchromatic behavior and could be used for long wavelengths. Ferrocene-free copper complexes were capable of efficiently initiating both the radical and cationic polymerizations and exhibited similar performances to that of the benchmark G1 system. Formation of acrylate/epoxy IPNs was also successfully performed even upon irradiation at 455 nm or at 530 nm. Interestingly, all copper complexes containing the 1,1′-bis(diphenylphosphino)ferrocene ligand were not photoluminescent, evidencing that ferrocene could efficiently quench the photoluminescence properties of copper complexes. Besides, these ferrocene-based complexes were capable of efficiently initiating free radical polymerization processes. The ferrocene moiety introduced in the different copper complexes affected neither their panchromatic behaviors nor their abilities to initiate free radical polymerizations.

Graphical abstract Several difunctional oligomers were synthesized by functionalizing perfluoropolyalkylether (PFPAE) chains with different vinyl ethers and epoxides end-groups. Due to their innate synthetic challenges and demanding purification protocols, the PFPAE derivatives were obtained in low yield and with an average functionality lower than 2. However, the functionalized PFPAE oligomers were successful in being used in photo-induced cationic polymerization processes, obtaining transparent and soft films. The influences of the fluorinated chains, and various end-groups on the photopolymerization process were investigated, as well their chemical stability, thermal degradation, and surface properties. Supplementary Information The online version contains supplementary material available at 10.1007/s00396-021-04838-1.

The aim of the present study was to investigate and compare the quantity of residual monomers leached from the bulk-fill composites with different compositions polymerized at varying layer thickness. Three bulk-fill (X-tra-fil, Beautifil Bulk Restorative, Fill-Up) and a nanohybrid composite (Filtek Z550) were used for the study. The composite resin samples were prepared with a stainless steel mold. For each composite, two groups were constructed. The samples in the first group were prepared using the 2 + 2 mm layering technique. In the second group, the composite samples were applied as a 4 mm-thick one layer and polymerized. Then, each composite samples were kept in a 75% ethanol solution and residual monomers released from composite resins were analyzed with an HPLC device after 24hour and 1 month. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests. Except the Fill-Up, all of residual monomer elution from the bulk-fill composites was significantly affected by the layer thickness (p < 0.05). The greatest monomer release was detected at 1 month after polymerization as a single 4 mm layer for Beautifil Bulk Restorative. Fill-Up composite showed similar residual monomer release in polymerization at different layer thicknesses compared to other composite resins. In the 2 + 2 mm layering technique, the least monomer elution was detected in the Filtek Z550 composite group. While Bis-GMA was the most released monomer in X-tra fil composite, UDMA was the most released monomer in all other composite resins. During polymerization of the bulk-fill composite, the layer thickness of the composite applied may affect the amount of residual monomers released from the composite resins. Conventional composites may release less monomer than bulk-fill composites when used with layering.

The present work highlights the synthesis and post-modification of silica-based micro-particles containing photo-responsive polymer brushes with photolabile o-nitrobenzyl ester (o-NBE) chromophores. For the synthesis of the polymer brushes, two different procedures were pursued. In the first approach, an amino-functional organosilane was covalently attached onto the silica surface followed by the thermal coupling of a mono-functional epoxy monomer containing o-NBE groups. In the second approach, a long wavelength absorbing Norrish Type I photoinitiator bearing functional trialkoxy silane moieties was immobilized across the silanol groups of the silica surface by condensation reaction. Upon visible light exposure, the photoinitator was homolytically cleaved and the formed radicals acted as anchor points for a grafting-from reaction. In particular, an acrylate monomer with o-NBE groups was grafted onto the surface of the micro-particles without inducing a premature cleavage of the o-NBE links. The photo-induced grafting reaction enabled the formation of photo-responsive polymer brushes within short reaction time and under mild reaction conditions. Once the polymer brushes were formed, the o-NBE groups were selectively cleaved upon UV light exposure. Additionally, particles with Janus-like properties were synthetized by first masking the grafted silica particles through a wax-water Pickering emulsion, followed by a selective UV irradiation of the unmasked particles’ domain. The formed carboxylic acid moieties were then used for the covalent attachment of a fluorescent biomolecule (Alexa Fluor546 conjugated Protein A). Zeta potential experiments and XPS spectroscopy confirmed the changes in the chemical surface composition of the silica particles prior to and after the surface modification and photocleavage processes. In addition, confocal microscopy images proved the selective anchoring of a fluorescent protein onto the surface of UV irradiated particles surface areas, giving rise to the versatility of o-NBE chemistry for the fabrication of light-responsive hybrid particles.

The use of electrically charged, polymerized ionic liquids (polyILs) offers opportunities for the development of gel–polymer electrolytes (GPEs), but the rational design of such systems is in its infancy. In this work, we compare the properties of polyIL/IL GPEs based on 1-butyl-3-(4-vinylbenzyl)imidazolium bis(trifluromethanesulfonyl)imide containing trapped ammonium-based protic ionic liquids (ILs) with an analogous series based on the electrically neutral host polymer 1-(4-vinylbenzyl)imidazole. The materials are synthesized by photopolymerizing ionic and neutral monomers in the presence of diethylmethylammonium trifluoromethanesulfonate, [dema][TfO], diethylmethylammonium trifluoroacetate, [dema][TFAc], and diethylmethylammonium bis[trifluoromethanesulfonyl]imide, [dema][Tf2N], respectively. The resulting materials are characterized using electron microscopy, infrared spectroscopy, thermal analysis, Raman spectroscopy, and AC-impedance analysis. Spectroscopic analysis confirms that the ILs are distributed throughout the polymers, unless the GPE also contains poly(diallyldimethylammonium) bis[trifluoromethanesulfonyl]imide, when separation of the components occurs. The polyIL/IL GPEs are more electrochemically and thermally stable, and up to six times more conductive, than the materials based on the neutral host. As a proof-of-concept demonstration, we show that polyIL/IL gels can be 3D printed using readily available 3D-printing hardware.

The highest disease caused by low back pain is herniated nucleus pulposus (HNP) where nucleus pulposus (NP) protrudes out through the annulus fibrosis. Injectable hydrogel is a method to restore NP function with minimal invasive surgery. Variation concentration of NFC were studied in detail toward affects on PEGDMA (poly(ethylene glycol)dimethacrylate):NFC hydrogel mechanically and injectability. The characteristics of PEGDMA and nanofibrillated cellulose (NFC) based injectable hydrogels through the photoinitiator Irgacure 2959 in the formation of hydrogels with variations composition 1:0; 1:0.25; 1:0.5; 1:0.75. In the morphological test on NFC a fibre with a diameter of 100 nm was formed from the results of electrospinning on ethyl cellulose (EC). The FTIR showed of photopolymerization of the conjugation bond between Irgacure 2959 and PEGDMA producing C-C at a frequency of 1349.20 cm−1. Swelling test used phosphate buffer saline (PBS) fulfilled the standard at a variation of 1:0.25; 1:0.5; and 1:0.75, 87.07%, 84.84% and 80.42% respectively. Viscosity test in the injectability of hydrogels showed a result of 73.67 dPa.s. The compressive strength test obtained good results in samples 1:0.75 showed a result of 3.42 kPa. In vitro injection model showed increasing of NFC concentration indicates the gel state when released from agarose will be less rupture. PEGDMA/NFC hydrogel biocomposite has the potential to be applied as an injectable hydrogel for the treatment of HNP patients based on the results.

International audience; In this work, the design of an original series of coumarin derivatives (CoumC1-CoumC13) is presented. Chemical structures of these coumarins were selected by molecular modelling to ensure both excellent light absorption properties and high potential photoreactivity (high excited state energy). As a striking result of this in-silico design, 8 of the 13 proposed coumarins were never presented and were specifically proposed for this work, evidencing the interest of the structures. New multi-component photoinitiating systems (PISs) based on these coumarins are proposed for the free radical polymerization (FRP) of (meth)acrylates and examined upon visible light irradiation using the light emitting diode (LED) as a safe and economical irradiation source. The proposed systems are based on coumarins which act as remarkable photoinitiators/photosensitizers (PIs/PSs) combined with N-phenylglycine (NPG) and/or iodonium salt (Iod) as co-initiators in order to generate the reactive species (radicals) that will initiate the photopolymerization recation. Investigation of the chemical mechanisms suggested by the different interactions that take place as well as the photophysical and photochemical properties of coumarins are provided. The access 2 to high polymerization rates (Rp), excellent photoinitiating abilities and great reactive function conversions (FC) is possible with these structures based on the coumarin core. Coumarins show high efficiency for the FRP of (meth)acrylates by reaction with iodonium salt (a photo-oxidation process) or with amine (a photo-reduction process). These compounds were used in 3D printing resins but also for the preparation of photocomposites. In this latter case, an excellent depth of cure was noted as remarkable behavior. To rationalize the experimental results, a kinetic model for a three-component system has been established to analyze the role of oxygen in the monomer conversions and the conversion enhancement observed while using an amine as a co-initiator.

In this study, copolymers were synthesized using methyl methacrylate (MMA) and 2-allyloxymethyl-1-methylimidazole (AOMMI) monomers at various ratios. For this purpose, hydroxyl end-functionalized imidazole was initially prepared with 1-methylimidazole and then it was used to prepare allyl-derived imidazole monomers. Finally, the synthesis of copolymers (poly(MMA-co-AOMMI)) was carried out using different proportions of commercial MMA and AOMMI monomers. Photopolymerization method was preferred as polymerization technique. The polymerization was carried out in solvent-free medium and benzophenone was used as the initiator. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (H-1 NMR and C-13 NMR) and elemental analysis were used for the structural characterization of the obtained copolymers. Molecular weights and the thermal behaviour of the synthesized copolymers were analysed with gel permeation chromatography (GPC) and thermogravimetry (TG) techniques, respectively. The surface of the products was tried to be illuminated using scanning electron microscopy (SEM). According to the obtained FTIR, NMR and elemental analysis results, the copolymers were successfully synthesized. A number average molecular weights of poly(MMA-co-AOMMI) samples were found 13,500 (MMA:2/AOMMI:1), 16,600 (MMA:1/AOMMI:2) and 17,300 (MMA:1/AOMMI:1) according to the mixing ratios. When the thermal stabilities of the synthesized copolymers were observed, it has been seen that those containing imidazole had higher stability than the neat PMMA.

In this study, it has been demonstrated that poly(styrene-co-1-methylpyrenyl methacrylate) macro-photoinitiator (PSMM) containing side chain pyrene moieties were successfully prepared using "radical polymerization method." Firstly, 1-pyrene methanol and methacryloyl chloride were reacted in dichloromethane for 24 h at 0 degrees C in order to give 1-methoxy pyrene methacrylate macromonomer. Then styrene was polymerized with this macromonomer to obtained macro-photoinitiator. the synthesized copolymer is also both computationally and experimentally demonstrated that the macro-photoinitiator obtained has similar absorption characteristics with the parent pyrene molecule. According to obtained results, the synthesized copolymer was more effective in the presence of triethyl amine as a macro-photoinitiator.

The controlled polymerization of a new biobased monomer, 4-oxocyclopent-2-en-1-yl acrylate (4CPA), was established via reversible addition-fragmentation chain transfer (RAFT) (co)polymerization to yield polymers bearing pendent cyclopentenone units. 4CPA contains two reactive functionalities, namely, a vinyl group and an internal double bond, and is an unsymmetrical monomer. Therefore, competition between the internal double bond and the vinyl group eventually leads to gel formation. With RAFT polymerization, when aiming for a degree of polymerization (DP) of 100, maximum 4CPA conversions of the vinyl group between 19.0 and 45.2% were obtained without gel formation or extensive broadening of the dispersity. When the same conditions were applied in the copolymerization of 4CPA with lauryl acrylate (LA), methyl acrylate (MA), and isobornyl acrylate, 4CPA conversions of the vinyl group between 63 and 95% were reached. The additional functionality of 4CPA in copolymers was demonstrated by model studies with 4-oxocyclopent-2-en-1-yl acetate (1), which readily dimerized under UV light via [2 + 2] photocyclodimerization. First-principles quantum mechanical simulations supported the experimental observations made in NMR Based on the calculated energetics and chemical shifts, a mixture of head-to-head and head-to-tail dimers of (1) were identified. Using the dimerization mechanism, solvent-cast LA and MA copolymers containing 30 mol % 4CPA were cross-linked under UV light to obtain thin films. The cross-linked films were characterized by dynamic scanning calorimetry, dynamic mechanical analysis, IR, and swelling experiments. This is the first case where 4CPA is described as a monomer for functional biobased polymers that can undergo additional UV curing via photodimerization. J.S., D.E.P.V., and K.V.B. acknowledge the project D-NL-HIT carried out in the framework of INTERREG-Program Deutschland-Nederland, which is co-financed by the European Union; the MVVIDE NRW; the Ministerie van Economische Zaken en Klimaat; and the provinces of Limburg, Gelderland, NoordBrabant, and Overijssel. The computational resources and services used in this work were provided by the VSC (Flemisch Supercomputer Center), funded by the Research Foundation Flanders (FWO) and the Flemisch Government department EWI. Bernaerts, KV (reprint author), Maastricht Univ, Fac Sci & Engn, AMIBM, NL-6167 RD Geleen, Netherlands. katrien.bernaerts@maastrichtuniversity.nl

International audience; 5,12-Dihydroindolo[3,2-a]carbazole is a polycyclic structure combining in its scaffold two carbazole moieties sharing a fused aromatic ring. Since the pioneering works reported in 2019 on this structure concerning the substitution of the two carbazoles by similar functional groups, no recent investigation has been devoted to asymmetrize the substitution of the two carbazoles. In this work, a series of 13 compounds based on the 5,12-dihydroindolo[3,2a]carbazole scaffold is presented. By carefully controlling the reaction conditions, functional groups such as a formyl, a nitro or an acetyl group could be selectively introduced on one of the two carbazoles. By combining X-ray diffraction and 2D NMR experiments, the higher reactivity of one of the two carbazoles could be clearly evidenced, enabling to generate asymmetrically substituted structures. Thanks to this unprecedented approach on the 5,12dihydroindolo[3,2-a]carbazole scaffold, the absorption of the resulting dyes could be shifted towards the visible range whereas the parent structure (5,12-dihexyl-6,7-diphenyl-5,12dihydroindolo[3,2-a]carbazole) exhibits a strongly UV-centered absorption. In light of their visible light absorption properties, several dyes have been examined as photoinitiators of polymerization activable at 405 nm and under low light intensity in two-component photoinitiating systems for the free radical polymerization of acrylates or the cationic polymerization of epoxides. Chemical mechanisms supporting the different polymerization processes have been fully elucidated by combining several techniques including cyclic voltammetry, UV-visible absorption and photoluminescence spectroscopy as well as photolysis experiments.

The of this study aim was to develop a rapid method to determine the chemical composition, solvent evaporation rates, and polymerization kinetics of dental adhesives. Single-component, acetone-containing adhesives One-Step (OS, Bisco, USA), Optibond Universal (OU, Kerr, USA), and G-Bond (GB, GC, Japan) were studied. Filler levels were determined gravimetrically. Monomers and solvents were quantified by comparing their pure Attenuated Total Reflectance-Fourier Transform Infra-Red (ATR–FTIR) spectra, summed in different ratios, with those of the adhesives. Spectral changes at 37 °C, throughout passive evaporation for 5 min, then polymerisation initiated by 20 s, and blue light emitting diode (LED) (600 mW/cm2) exposure (n = 3) were determined. Evaporation and polymerisation extent versus time and final changes were calculated using acetone (1360 cm−1) and methacrylate (1320 cm−1) peaks. OS, OU, and GB filler contents were 0, 9.6, and 5.3%. FTIR suggested OS and OU were Bis-GMA based, GB was urethane dimethacrylate (UDMA) based, and that each had a different diluent and acidic monomers and possible UDMA/acetone interactions. Furthermore, initial acetone percentages were all 40−50%. After 5 min drying, they were 0% for OS and OU but 10% for GB. Whilst OS had no water, that in OU declined from 18 to 10% and in GB from 25 to 20% upon drying. Evaporation extents were 50% of final levels at 23, 25, and 113 s for OS, OU, and GB, respectively. Polymerisation extents were all 50 and 80% of final levels before 10 and at 20 s of light exposure, respectively. Final monomer polymerisation levels were 68, 69, and 88% for OS, OU, and GB, respectively. An appreciation of initial and final adhesive chemistry is important for understanding the properties. The rates of evaporation and polymerisation provide indications of relative required drying and light cure times. UDMA/acetone interactions might explain the considerably greater drying time of GB.

Made available in DSpace on 2022-05-01T09:47:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The photopolymerization process has been widely studied due to its use in painting/coating, dentistry, creating photoresist materials and more recently in 3D printing. Therefore, new monomers have been synthesized to be used in this growing area. Here, a new Brazilian biomass derived, renewable monomer from macaw vegetable oil is presented. This monomer can self-polymerize without photoinitiation under UV light, reaching a monomer conversion of 75% and a conversion of 88% when ethyl 4-(dimethylamino)benzoate is present as a coinitiator. Furthermore, the final polymer has an orange color under visible light and exhibits fluorescence (a blue color) under UV radiation. Monomers and polymers formed from macaw (macaúba) vegetable oil are thermally stable up to 220 °C, as evidenced by thermogravimetry (TG). The polymers formed also exhibited a glass transition temperature of 2.6 °C, as observed in differential scanning calorimetry (DSC) curves and dynamic-mechanical analysis (DMA). This new monomer presents an alternative monomer to be used in 3D printing, in a similar manner to other vegetable oils such as soybean and linseed. School of Science Department of Chemistry UNESP - São Paulo State University Department of Chemical and Biological Engineering University of Sheffield, Mappin Street São Carlos Institute of Chemistry Green Chemistry Centre of Excellence Department of Chemistry The University of York School of Science Department of Chemistry UNESP - São Paulo State University FAPESP: 2018/03460-6

In this work, the design and characterization of new supported ionic liquid membranes, as medium-temperature polymer electrolyte membranes for fuel-cell application, are described. These membranes were elaborated by the impregnation of porous polyimide Matrimid® with different synthesized protic ionic liquids containing polymerizable vinyl, allyl, or methacrylate groups. The ionic liquid polymerization was optimized in terms of the nature of the used (photo)initiator, its quantity, and reaction duration. The mechanical and thermal properties, as well as the proton conductivities of the supported ionic liquid membranes were analyzed in dynamic and static modes, as a function of the chemical structure of the protic ionic liquid. The obtained membranes were found to be flexible with Young’s modulus and elongation at break values were equal to 1371 MPa and 271%, respectively. Besides, these membranes exhibited high thermal stability with initial decomposition temperatures &gt, 300 °C. In addition, the resulting supported membranes possessed good proton conductivity over a wide temperature range (from 30 to 150 °C). For example, the three-component Matrimid®/vinylimidazolium/polyvinylimidazolium trifluoromethane sulfonate membrane showed the highest proton conductivity—~5 × 10−2 mS/cm and ~0.1 mS/cm at 100 °C and 150 °C, respectively. This result makes the obtained membranes attractive for medium-temperature fuel-cell application.

This article describes a comprehensive study to obtain polymeric porous materials via a photopolymerization technique, using acrylate-based high internal phase emulsions (HIPEs), as a template. The aim of obtaining these polymers was to use them as hydrocarbon absorbing materials. Kinetics of photopolymerization of the acrylate monomers and of the HIPEs were conducted to optimize the process. The obtained monoliths were characterized by thermal analysis such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The morphology and surface area were analyzed by scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis. The compression properties of the materials were determined, as well as their absorption properties of hydrocarbons such as hexane, diesel, toluene and chloroform. The findings show that the acrylate-HIPEs displayed high reactivity photopolymerizing in 20 min. The glass transition temperature of the materials were in the range of 2 to 83 °C, depending on the ratio of acrylates in the photocurable formulation, displaying the characteristic morphology with voids and interconnecting windows. The polyHIPEs exhibited superior properties of absorption of the studied hydrocarbons. The order of capability of absorption was chloroform &gt, toluene &gt, hexane &gt, diesel. The optimum absorbing material was that with trimethylolpropane triacrylate, ethylhexyl acrylate and isobornyl acrylate in a 1:0.9:2.1 ratio, which absorbed 778% of chloroform, 378% of toluene, 306 % of hexane and 236% of diesel.

A trifunctional photoinitiator based on commercial photoinitiators 2-hydroxy-2-methylpropiophenone (Irgacure1173) and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure2959) was synthesized by an esterization reaction. Its structure was characterized by UV-Vis spectrometry, Infrared Transformed Fourier, Proton Nuclear Magnetic Resonance Spectra, 13 Carbon Nuclear Magnetic Resonance Spectra, Mass Spectrometry, and Thermogravimetry. In addition, its photoinitiating activity was investigated. The results showed that the novel photoinitiator had good photoinitiating activity and thermal stability compared to commercial photoinitiators. The migration of the residual photoinitiator in the cured film was lower than that of 1173 and 2959.

International audience; The development of visible-light 3D printing technology by using water-soluble initiatingsystems has attracted widespread attention due to their potential applications in the manufactureof hydrogels. Besides, at present, the preparation of water-soluble photoinitiators suitable forvisible light irradiation (such as LEDs) still remains a challenge. Therefore, this work is devotedto developing water-soluble photoinitiators (PI)/photoinitiating systems (PIS) upon irradiationwith a LED @ 405 nm. In detail, a new water-slightly-soluble chalcone derivative dye [(E)-3-(4-(dimethylamino) phenyl)-1-(4-(2-(2-(2-methoxyethoxy) ethoxy) ethoxy) phenyl) prop-2-en-1-one] wassynthesized here and used as a PI with a water-soluble coinitiator, i.e., triethanolamine (TEA) whichwas also used as an electron donor. When combined together, a charge transfer complex (CTC) formedimmediately which exhibited excellent initiating ability for the free radical photopolymerizationof poly(ethyleneglycol)diacrylate (PEG-DA). In light of the powerful CTC effect, the [dye-TEA]CTC could not only exhibit enhanced water solubility and mechanical properties but could also beeffectively applied for 3D printing. This CTC system is environmentally friendly and cost-savingwhich demonstrates a great potential to prepare hydrogels via photopolymerization.This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY)

As a smart stimulus-responsive material, hydrogel has been investigated extensively in many research fields. However, its mechanical brittleness and low strength have mattered, and conventional photoinitiators used during the polymerization steps exhibit high toxicity, which limits the use of hydrogels in the field of biomedical applications. Here, we address the dual functions of graphene quantum dots (GQDs), one to trigger the synthesis of hydrogel as photoinitiators and the other to improve the mechanical strength of the as-synthesized hydrogel. GQDs embedded in the network effectively generated radicals when exposed to sunlight, leading to the initiation of polymerization, and also played a significant role in improving the mechanical strength of the crosslinked chains. Thus, we expect that the resulting hydrogel incorporated with GQDs would enable a wide range of applications that require biocompatibility as well as higher mechanical strength, including novel hydrogel contact lenses and bioscaffolds for tissue engineering.

Detailed kinetics for a 3-wavelength photopolymerization confinement (PC) system is presented for both numerical solutions and analytic formulas. The dynamic profiles of oxygen, free radicals, and monomer conversion for various situations of: blue-light only, 2-light (red and UV), and 3-light (red, blue, UV) are obtained. Higher oxygen concentration leads to a lower conversion, which could be enhanced by reducing the S-inhibition via a red or blue light pre-irradiation. We found that pre-irradiation time is given by TP = 200 s for red-light only, and reduced to 150 s, for both red and blue-light. The system under UV-only leads to a conversion lower than that of blue-only. However, conversion could be improved by the dual-light (blue and UV), and further enhanced by the pre-irradiation of red-light. The two competing factors, N-inhibition and S-inhibition, could be independently and selectively tailored to achieve: (i) high conversion of blue-light (without UV-light), enhanced by red-light pre-irradiation for minimal S-inhibition; and (ii) efficient PC initiated by UV-light produced N-inhibition for reduced confinement thickness and for high print speed.

Halogen bonding (XB) has been used to catalyze organic reactions and polymerizations, which is an emerging research area. Reversible complexation mediated polymerization (RCMP) is an XB-catalyzed living radical polymerization and is one of the most promising examples of the XB catalysis. RCMP utilizes alkyl iodides as initiating dormant species and electro-donating molecules and ions such as amines, iodide anions, and oxyanions as catalysts. Various initiating dormant species and catalysts were developed, enabiling the synthesis of well-defined homopolymers and block copolymers with complex architectures, chain-end functionalization, photo-polymerization, and industrial application. The use of inexpensive non-metallic catalysts and the accessibility to a wide range of polymer structures are attractive features of RCMP. This mini-review summarizes the current research status of RCMP and its uniqueness brought via the XB catalysis. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This work was supported by National Research Foundation (NRF), Singapore, under its National Research Foundation Investigatorship (NRF‐NRFI05‐2019‐0001) and Ministry of Education, Singapore, under its Academic Research Fund (AcRF) Tier 2 (MOE2017‐T2‐1‐018).