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This article reports the synthesis of a novel perfluoropolyalkylether (PFPAE) vinylether monomer and its use as a comonomer in the thiol‐ene photopolymerization of a trifunctional thiol together with a trifunctional vinylether. The crosslinked copolymers are obtained in the form of few mm thick layers and characterized. By changing the thiol/ene ratio, the polymers are optimized to tailor their surface composition and obtain adhesion between two thick layers despite the presence of the fluorinated monomer. The final bilayered structures are adhesive, and appeared chemically resistant, with good dimensional stability: therefore, these fluorinated thiol–ene based copolymers are likely to be of interest for applications based on layer‐by‐layer processes, such as additive manufacturing and microfluidics. [ABSTRACT FROM AUTHOR]

Vanillyl alcohol has emerged as a widely used building block for the development of biobased monomers. More specifically, the cationic (photo‐)polymerization of the respective diglycidyl ether (DGEVA) is known to produce materials of outstanding thermomechanical performance. Generally, chain transfer agents (CTAs) are of interest in cationic resins not only because they lead to more homogeneous polymer networks but also because they strikingly improve the polymerization speed. Herein, the aim is to compare the cationic chain‐growth photopolymerization with the thermally initiated anionic step‐growth polymerization, with and without the addition of CTAs. Indeed, CTAs lead to faster polymerization reactions as well as the formation of more homogeneous networks, especially in the case of the thermal anionic step‐growth polymerization. Resulting from curing above the TG of the respective anionic step‐growth polymer, materials with outstanding tensile toughness (>5 MJ cm−3) are obtained that result in the manufacture of potential shape‐memory polymers. [ABSTRACT FROM AUTHOR]

Supramolecular assemblies with chirality inversion were developed using a co-assembly system comprising solvent monomers and a pyridine-cholesterol gelator. The polarity-dependent chiralities were captured in situ through photopolymerization, enabling the formation of multi-color circularly polarized luminescence films. [ABSTRACT FROM AUTHOR]

Incorporation of polymer chain entanglements within a single network can synergistically improve stiffness and toughness, yet attaining such dense entanglements through vat photopolymerization additive manufacturing [e.g., digital light processing (DLP)] remains elusive. We report a facile strategy that combines light and dark polymerization to allow constituent polymer chains to densely entangle as they form within printed structures. This generalizable approach reaches high monomer conversion at room temperature without the need for additional stimuli, such as light or heat after printing, and enables additive manufacturing of highly entangled hydrogels and elastomers that exhibit fourfold- to sevenfold-higher extension energies in comparison to that of traditional DLP. We used this method to print high-resolution and multimaterial structures with features such as spatially programmed adhesion to wet tissues. [ABSTRACT FROM AUTHOR]

We report on concomitant photoinitiated polymerization‐induced macrophase and microphase separation strategies to produce hierarchically structured recyclable poly(n‐butyl acrylate) based elastomeric materials. The investigated crosslinker‐free formulations are composed of n‐butyl acrylate monomer and a UV photo‐initiator mixed with poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate)‐poly(methyl methacrylate) ABA triblock copolymers. Two different pre‐synthesized copolymers are used to control the macrophase separation. One synthesized by nitroxide‐mediated radical polymerization (NMRP), and a second by anionic polymerization (AP). Essentially, NMRP route leads to copolymer with unsaturated chain ends, activated during UV photopolymerization. On the other hand, the copolymer synthesized by AP are chemically inert. That dissimilarity is also highlighted by time‐resolved FTIR and SAXS, performed to monitor respectively monomer conversion and nanostructure evolution during photopolymerization. The experimental data demonstrate that the reactivity of the triblock copolymer impacts drastically the polymerization kinetics and the self‐assembly processes. Finally, the rheological analysis shows that the produced materials present a solid‐like behavior at low frequencies despite a large PnBA content (i.e., 85 wt%). This property is associated to the phase segregation and to the sample hierarchical morphology. [ABSTRACT FROM AUTHOR]

Here, methacrylated gelatin (GelMA) is obtained at different methacrylate anhydride concentrations (5.8% and 10% v/v), different reaction times (1 and 3 h), and under pH control. A ninhydrin test and nuclear magnetic resonance are used to determine the degree of functionalization (DoF) of the samples showing that pH controlling produces better functionalization degrees than an increase in methacrylate anhydride concentration or longer reaction times. The photopolymerization process of GelMA samples is studied by time‐resolved photoluminescence at different photoinitiator (PI) concentrations: 0.5%, 1%, and 2% w/v. An increase in PI concentration and DoF produces changes in the cross‐link. The 2% w/v concentration produces a higher reaction speed in the first 10 min and requires longer times to end the reaction. No significant differences are found in the use of smaller concentrations. [ABSTRACT FROM AUTHOR]

Photopolymerization of a hybrid methacrylate‐norbornene‐thiol system is used for the solvent‐free synthesis of polymers with tunable physical and mechanical properties. We demonstrate competitive adhesive performance of this system by examining factors such as thiol:ene ratio, thiol functionality, and the incorporation of a methacrylate as a hard monomer. Firstly, ethylene glycol dicyclopentenyl ether methacrylate (EGDEMA) and the di‐functional thiol ethylene bis(3‐mercapto propionate) (EBM) are photopolymerized to produce crosslinked networks with high conversion (up to 100%), high gel content (up to 77%), and low Tg (−2.5 to −13.5°C). Rheological studies found these formulations satisfied the Dahlquist criteria for pressure‐sensitive adhesives (PSAs) with the best adhesive/cohesive performance at thiol:ene ratios = 0.5–0.75. Secondly, a tetra‐functional thiol (PEMP) is crosslinked with EGDEMA photochemically, yielding elastomeric polymer films made to high conversion (up to 100%), with comparatively higher Tg (9–17°C), and higher gel content (up to 100%). Finally, isobornyl methacrylate (IBOMA) is incorporated as a hard monomer and crosslinked with a bifunctional thiol to produce thermoplastic polymers with negligible gel content and variable Tg (−12 to 41°C), suitable for application as temporary adhesives. These findings propose the use of the hybrid system in one‐step solventless formulations for UV curable adhesives, depending on component selection. [ABSTRACT FROM AUTHOR]

Hybrid epoxide–acrylate photopolymerization enables the temporal structuring of polymer networks for advanced material properties. The ability to design polymer network architectures and to tune mechanical properties can be realized through the control of the cationic active center propagation reaction (active chain end mechanism) relative to the cationic chain transfer reaction (activated monomer mechanism). Grafted polymer networks (GPNs) can be developed through the covalent bonding of epoxide chains to acrylate chains through hydroxyl substituents, making hydroxyl-containing acrylates a promising class of chain transfer agents. This work demonstrates the formation of these GPNs and explores the physical properties obtained through the control of hydroxyl content and hybrid formulation composition. The GPNs exhibit a lower glass transition temperature than the neat epoxide network and result in a more homogeneous network. Further investigations of hydroxyl-containing acrylates as chain transfer agents will generate a wider range of physical property options for photopolymerized hybrid coatings, sealants, and adhesives. [ABSTRACT FROM AUTHOR]

An approach of 'polymerization of monomers in its aggregated form' is unprecedentedly introduced to (i) tailor the water wettability of fibrous and porous substrates from hydrophobicity to superhydrophobicity, and (ii) associate patterned wettability. A solution of selected monomers—i.e., alkyl acrylate in a good solvent (indicating high solubility; ethanol) was transferred into a bad solvent (refers to poor solubility; water) to achieve a stable dispersion of monomer aggregates of size <1 μm for deposition on fibrous and porous substrates. Its photopolymerization provided a durable coating with the ability to tailor the water wettability from 134° to 153°. Furthermore, a spatially selective photopolymerization process yielded a patterned interface of superhydrophilicity and superhydrophobicity. Such a facile chemical approach with the ability to provide a durable coating embedded with tailored and patterned wettability would be useful for various potential applications. [ABSTRACT FROM AUTHOR]

Polymer systems induced by the reaction between monomers and photo-initiators play a crucial role in the formation of volume-phase gratings. In this paper, we fabricated a dual-photo-initiator photopolymer by doping EY (Eosin Yellow) molecules into a TI (Titanocene, Irgacure 784@BASF) dispersed PMMA (poly-[methyl methacrylate]) substrate system, with the aim of promoting the diffusion and polymerization processes in volume holographic storage. The two-wave interference system is adopted to record a permanent grating structure in our materials. The temporal diffraction variations of photopolymerization (during the interference exposure) and dark diffusion (after the interference exposure) processes have been investigated and analyzed. Aiming to analyze the influence of EY doping ratios on holographic performances, some key parameters were examined in the experiment. We first measured the temporal evolution of diffraction efficiency, then an exponential fitting was adopted to obtain the response time. Finally, the angular selectivity was evaluated by the Bragg condition after holographic recording. Also, the temporal evolution of each component is described by the nonlocal polymerization-driven diffusion model with a dual-photo-initiator composition, theoretically. Furthermore, we experimentally achieved the holographic grating enhancement in both the dark diffusion and photopolymerization processes by doping appropriate EY concentrations, respectively. This work provides a foundation for the acceptability of TI&EY/PMMA polymers in further holographic storage research. [ABSTRACT FROM AUTHOR]

Novel method of obtaining functional acrylic resins (FARs) containing carboxyl- and benzophenone groups (in-chain functionalization) and terminal Br atoms was verified. Acrylic oligomers were prepared by a solution-free, UV-initiated telomerization process of basic monomer (n-butyl acrylate) and functional monomers (acrylic acid and 4-acrylooxybenzophenone) in the presence of radical photoinitiator and different amount of tetrabromomethane (CBr4) as telogen. The effect of telogen content on UV-telomerization kinetics as well as physicochemical and thermal (Tg) properties of FARs was investigated. A telogen content higher than 5 wt. parts does not affect the UV-telomerization rate (photo-DSC), the molecular weights of telomers (GPC), or their glass transition temperature (DSC), but it significantly increases the conversion of monomers (up to 88%) and lowers the viscosity of FARs (approx. 6 Pa·s). NMR studies confirmed the inclusion of CBr4 in the structure of functional acrylic telomers. [ABSTRACT FROM AUTHOR]

This publication describes the influence of residue monomers in synthesized pressure-sensitive adhesives based on acrylics on their main properties—tack, peel adhesion, shear strength and shrinkage—in the form of transfer tapes used for joining wooden elements in the furniture industry. The discussed carrier-free adhesive tapes are synthesized via photo-crosslinking and photopolymerization with UV radiation of the photoreactive prepolymers sandwiched between two adhesive siliconized polyester films. The simultaneous crosslinking and polymerization processes carried out under UV lamps placed simultaneously above and below the crosslinked photoreactive polymer layer lead to the production of a carrier-free adhesive film. The preliminary target of these studies was to investigate how the intensity of UV radiation and the time of its exposure affect the viscosity of the photoreactive compositions and the content of unreacted monomers in them. Next, the influence of the crosslinking agent concentration and UV irradiation time on the content of unreacted monomers after the crosslinking process was tested. The last step of the studies was the investigation of the influence of the residue monomer concentration on the application properties of the obtained pressure-sensitive adhesive layers. The typical PSA application properties were tested on the wood samples: tack, peel adhesion, shear strength (cohesion) and shrinkage. [ABSTRACT FROM AUTHOR]

The aim of this study is to synthesize two eugenol‐derived halogenated monomers and to evaluate their properties as antibacterial and antifungal agents in the formulation of dental composite resins. The 4‐allyl‐2‐methoxyphenyl (2‐chloroethyl) carbonate (ECl) and 4‐allyl‐2‐methoxyphenyl 2,2,3,3,4,4,4‐heptafluorobutanoate (EF) monomers have halogens, chlorine or fluorine bonded in their structure, whose antibacterial activity is known. The characterization of ECl and EF monomers was made by Fourier transform infrared and 1H and 13C NMR. dental resin composites are formulated by mixing the BisGMA/TEGDMA, photoinitiator system, inorganic filler, and the ECl or EF monomer, respectively. The antimicrobial and antifungal activity of the experimental resins is determined using the strains of Staphylococcus aureus and Candida albicans. After copolymerization, DCRs with ECl or EF monomers significantly stop antibacterial growth and show excellent antifungal effect. The best results in the antibacterial test are using 0.5 or 3 wt% of the ECl monomer, while for the EF monomer is 5 wt%. On the other hand, the most adequate concentration of ECl and EF monomers in the antifungal activity is 0.5 wt%. The above demonstrates the ability of ECl and EF monomers to prevent antibacterial and antifungal growth in a dental composite resin, which would extend the useful life of a dental restoration. [ABSTRACT FROM AUTHOR]

Recently, there has been an increasing interest in the synthesis of bio-derived and sustainable polymers due to limited petroleum resources and the dependence of polymer chemistry on fossil fuels. Terpenes which are found in nature in wide variety of structures, are a large family derived from plants. Isoprene like structure of terpenes make these natural compounds susceptible to polymerization. In this work, β-myrcene, which is an acyclic monoterpene was used in the synthesis of photocurable porous polymer monoliths via high internal phase emulsion (HIPE) templating. Photocuring of β-myrcene in HIPE templates has been achieved by the free radical copolymerization crosslinking reaction with 1,4-butanediol dimethacrylate (1,4-BDDMA). To determine the effect of monomer ratio on the crosslink density and pore morphology of the resulting polyHIPEs, the volume ratio of β-myrcene in the external phase has been varied from 10 to 90. Crosslink density of the polyHIPEs has been calculated by swelling experiments using Flory-Rehner Theory. In the end, polyHIPEs exhibiting pore morphology constituted of cavities and interconnected pores has been obtained in all cases. However, it has been determined that 60% is the optimum β-myrcene ratio to obtain a highly crosslinked polyHIPE accompanied with an open-cellular pore morphology. [ABSTRACT FROM AUTHOR]

The cycloaliphatic epoxy compounds have been widely used as the monomers in cationic photopolymerization and the fluorine‐modified organosilicon materials combine the merits of both organosilicon and organofluorine. In this work, three trifluoromethyl organosilicon cycloaliphatic epoxy monomers with different chain length (CE‐FSin, n = 3, 6, 9) were designed and prepared by using a facile two‐step synthesis and very competitive raw materials. CE‐FSin showed good ability to cationically photopolymerize. The final conversion of the alicyclic epoxy group of CE‐FSin systems reached up to 84.0% under the irradiation for 900 s. The addition of CE‐FSin enhanced the surface water repellency, heat resistance, elongation at break and glass transition temperature (Tg) of the cured film because of the presence of organosilicon chain and trifluoromethyl group of CE‐FSin. The cured film of CE‐FSi3‐0.5% had the largest water contact angle (105.0°), while the cured film of CE‐FSi9‐0.5% had tensile strength of 0.49 MPa and elongation at break of 68.51% that was three folds as that of the blank control. The addition of CE‐FSin had no obvious influences on the adhesion forces of the cured films, but decreased the pencil hardness. [ABSTRACT FROM AUTHOR]

Supramolecular polymers can substantially influence the dynamic mechanical properties in slightly crosslinked polymer networks. One prominent example of supramolecular building blocks is 2‐ureido‐4[1H]‐pyrimidinones (UPy). Combining UPy‐terminated supramolecular segments with classical covalent‐reactive monomers implements dynamic behavior in photopolymerizable systems. In this work, a UPy‐based methacrylic monomer (up to 20 mol%) was introduced in a classical photopolymerizable methacrylate matrix. The influence of the UPy‐motif on the reactivity and (thermo)mechanical properties was investigated via RT‐NIR photorheology, DMTA, and tensile testing. The dynamic behavior was characterized via stress relaxation and reprocessing studies to demonstrate the dynamic effects of photopolymers containing the UPy building block compared to difunctional photopolymers with similar structural features. In a final step, the UPy‐based photopolymerizable system was applied in bulk in a Hot Lithography printing process at elevated temperatures yielding complex 3D‐printed parts with high resolution and precision. [ABSTRACT FROM AUTHOR]

Polyelectrolyte complexes (PECs), assemblies of oppositely charged polymers with powerful properties and wide‐ranging applications, are currently not melt‐processable via any conventional means and have been limited commercially to applications only as coatings. Herein, a unique strategy of pairing a polycation with an oppositely charged photopolymerizable monomer is employed. Vat photopolymerization of this mixture yields 3D spatial control over PECs for the first time. The properties of these 3D‐printed PECs are evaluated and are found to be similar to conventionally studied PEC materials. The water sensitivity of the PEC parts is adjustable through the incorporation of a small amount of a hydrophilic covalent crosslinker, highlighting potential future applications of these materials in 4D printing. Finally, the upcyclability of the additively manufactured PECs is demonstrated through the dissolution of a printed part and its incorporation into virgin resin to yield a part composed of partially recycled material. This chemistry has the potential to dramatically expand the application space of PEC materials and is a step towards a more circular economy for the field of additive manufacturing. [ABSTRACT FROM AUTHOR]

Surface imprinting used for protein recognition in functional cavities is highly effective in imprinting biomacromolecules to avoid template encapsulation during the formation of a molecularly imprinted polymer (MIP) matrix. Herein, we introduce a facile surface-imprinting method based on two-step spin-coating and photopolymerization to design highly efficient imprinted sites on polymeric films to detect trypsin (TRY). Well-distributed template imprinting is successfully achieved for maximized sensing responses by controlling the composition of functional monomers and crosslinkers in the precursor solution and the concentration of TRY in the imprinting solution. The MIP film exhibits higher sensitivity (−841 ± 65 Hz/(μg/mL)) with a coefficient of determination of 0.970 and a higher imprinting factor of 4.5 in a 0.24 µg/mL TRY solution compared to the nonimprinted polymer (NIP) film. Moreover, the limit of detection and limit of quantification are calculated to be 25.33 and 84.42 ng/mL, respectively. Finally, the selectivity coefficient is within the range of 3.90–6.78 for TRY against other proteins. These sensing properties are superior to those of the corresponding nonimprinted polymer matrix. Thus, the proposed facile surface-imprinting method is highly effective for protein imprinting with high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

In this paper, epoxy-acrylate structural adhesives tapes (SATs) were obtained from Bisphenol A-based liquid epoxy resin and epoxy acrylic resins (EARs). A new method of EARs preparation, i.e., the free radical bulk photopolymerization process (FRBP), was studied in detail. The influence of methacrylic monomers (methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate, (2-acetoacetoxy)ethyl methacrylate) and vinyl monomers (N-vinylpyrrolidone and styrene) on the FRBP process of base monomers (i.e., butyl acrylate, glycidyl methacrylate and 2-hydroxyethyl acrylate) was investigated. The kinetics of photopolymerization process was monitored by photo-differential scanning calorimetry method. The properties of the obtained EARs (viscosity and average molecular weights), as well as monomers conversion using 1H NMR, were determined. It was revealed that styrene significantly decreases the photopolymerization rate and increases the final monomers conversion (+27%). However, the resulting tetrapolymers BA-co-GMA-co-HEA-co-STY have low molecular weights and low polydispersity (2.2). Methacrylate monomers with shorter aliphatic chains (

Photochemical techniques have recently been revitalized as they can readily be adapted to different polymerization modes to yield a wide range of complex macromolecular structures. However, the implementation of the photoinduced cationic methods in the polymerization of cyclic siloxane monomers has scarcely been investigated. Octamethylcyclotetrasiloxane (D4) is an important monomer for the synthesis of polydimethylsiloxane (PDMS) and its copolymers. In this study, the cationic ring-opening polymerization (ROP) of D4, initiated by diphenyl iodonium hexafluorophosphate (DPI), has been studied. Both direct and indirect initiating systems acting at broad wavelength using benzophenone and pyrene were investigated. In both systems, photochemically generated protonic acids and silylium cations are responsible for the polymerization. The kinetics of the polymerization are followed by viscosimetry and GPC analyses. The reported approach may overcome the problems associated with conventional methods and therefore represents industrial importance for the fabrication of polysiloxanes. [ABSTRACT FROM AUTHOR]

Polydiacetylene (PDA) material-based colorimetric sensors have been devised for monitoring ultraviolet-C (UVC) light. However, it is rather difficult to systematically control their sensitivity. This work introduces an easy and inexpensive approach for developing diacetylene/zinc(II)/zinc oxide (DA/Zn2+/ZnO) nanocomposites as colorimetric sensors of UVC light. Here, we demonstrate the ability to tune the sensitivity of the nanocomposites to UVC light by varying different parameters including ZnO ratio, ZnO size, and alkyl chain length of DA monomers. We have found that the increase of ZnO ratio significantly enhances the UVC sensitivity. Furthermore, the color transition from blue to purple upon prolonged exposure to UVC light can be controlled by adjusting the ZnO ratio. Interestingly, the use of ZnO quantum dots with a diameter of 3.8 nm drastically increases the sensitivity to UVC light. The adjustment in DA alkyl chain length also enables fine-tuning of sensitivity. The shortening of the alkyl chain length at the tail and headgroup position strongly influences the color-transition behaviors of the nanocomposites upon increasing the UVC irradiation time. Two different types of UVC sensors can be fabricated including flexible film and hydrogel bead sensors. These sensors exhibit a color transition from yellow to green to red as UVC exposure increases from 0 to 16.4 J/cm2. [Display omitted] • Diacetylene/zinc(II)/zinc oxide (DA/Zn2+/ZnO) nanocomposites are developed as colorimetric sensors of UVC light. • Sensitivity to UVC can be systematically tuned by varying ZnO ratios. • Blue-to-purple color transition depends on ZnO ratio and DA alkyl side chain. • Use of small size ZnO quantum dots enhances the sensitivity to UVC. • Flexible film and hydrogel bead colorimetric UVC sensors are fabricated. [ABSTRACT FROM AUTHOR]

• Micron-sized silver reduces slurry viscosity by 60% for nano-hydroxyapatite slurry. • Silver flakes increase sintering density of printed structures to 95%, versus 92% for pure hydroxyapatite (HA). • Adding over 5% silver reduces slurry's cured depth, leading to poor printability. • Potential for biomedical implants with improved strength and antibacterial properties. The present work deals with the processing of HA-silver photocurable slurry to make composites using the Vat-photopolymerization process. Slurries with increasing amount of silver addition in the HA-Ag (0, 5, 10, 15%) slurry have been prepared using monomers with photo-initiators and printed successfully. Silver powder used in this study is in the form of flakes and spheres. A shear thinning behaviour of all the compositions of the slurries has been observed which is essential to fabricate defect-free parts. With increase in silver addition to 15 wt%, the viscosity decreased by around 60 % however curing depth was compromised. From SEM micrographs it was observed that HA with silver flakes showed better sintering with sintering density of 95% compared to only HA and HA with spherical silver samples. [ABSTRACT FROM AUTHOR]

• A simple in situ photopolymerization technique to produce homogeneous perovskite-silicone elastomer composites. • The fabrication process is completed in 5 min under UV irradiation at ambient conditions. • The mechanical property of composite is tunable from rigid to elastic. • The superb properties of composite enable optical visualization tracking for magnetically driven soft robots. Metal halide perovskite (CsPbX 3 , X = Cl, Br, I) nanocrystals (MHP NCs) have been widely investigated for a variety of optoelectronic applications due to their superior photophysical characteristics. However, the inherent poor stability has limited broad applications. Herein, a facile in situ photopolymerization strategy using MHP NCs as photo-initiators is designed to fabricate homogeneous perovskite-silicone composites with outstanding stability, flexibility, and scalability. The fabrication process is completed upon exposure to 30 W ultraviolet light for 5 min under ambient conditions without additional protections and additives. The composites have exceptional stability in air and can even withstand harsh conditions, such as a basic pH of 13 for six months. The mechanical properties of composites are tunable from rigid to elastic by regulating the composition, ratios of polymerization monomers, and reaction time. Their superb properties enable optical visualization tracking for magnetically driven soft robots. This convenient and effective approach opens a new pathway for future applications in optical tracking, soft displays, biological detection, and bioimaging of perovskite nanocrystals. [ABSTRACT FROM AUTHOR]

3D ceramic parts are of great interest for various applications including aerospace, defense, electronics, photonics, and biomedical. Yet, additive manufacturing of ceramics is challenging due to their poor machinability. Herein, two approaches based on the chemical modification of silicon resins to obtain UV‐curable preceramic precursors of SiOC are described. The dual functionality of the synthesized resins acting both as preceramic precursor and as photopolymerizable entity under UV light is exploited. A set of characterization techniques has allowed the investigation of the mechanisms involved in the synthesis of the inorganic SiOC precursors according to the following approaches: (1) blend of the silicon resin with photoactive monomers and (2) synthesis of a single source UV‐curable preceramic silicon resin. A correlation between the nature of the precursor and the properties of the derived SiOC is analyzed. From a technological point of view, the materials can be fabricated as dense or crack‐free porous customized objects with low mass loss and optimal surface quality. [ABSTRACT FROM AUTHOR]

This study reports the utility of solid camphor as a novel diluent in photocurable hexanediol diacrylate (HDDA) monomer to manufacture 4 mol% yttria partially stabilized zirconia (4Y-PSZ) components for dental applications by digital light processing (DLP). The use of a 65 wt% HDDA–35 wt% camphor solution allowed 4Y-PSZ suspensions to have reasonably low viscosities (1399 ± 55.8 mPa·s at a shear rate of 75 s−1), measured by a cone/plate viscometer, at a high solid loading of 48 vol%, where 4Y-PSZ particles prepared by calcination of as-received 4Y-PSZ granules, followed by a ball-milling process, were used with assistance of a dispersant. These 4Y-PSZ suspensions could be successfully applied to our custom-made DLP machine for manufacturing 4Y-PSZ components. To this end, several processing parameters, including layer thickness of 4Y-PSZ suspension, UV illumination time for layer-by-layer photocuring process, and initial dimensions of 4Y-PSZ objects, were tightly controlled. As sintering temperature increased from 1300 °C to 1500 °C, relative density and grain size of 4Y-PSZ objects increased, and cubic phase content also increased. Thus, after sintering at the highest temperature of 1500 °C for 3 h, high mechanical properties (biaxial flexural strength = 911 ± 40.7 MPa, hardness = 1371 ± 14.4 Hv) and reasonably high optical transmittance (translucency parameter = 7.77 ± 0.32, contrast ratio = 0.809 ± 0.007), evaluated by a spectrophotometer, were obtained due to a high relative density (97.2 ± 1.38%), which would be useful for dental applications. [ABSTRACT FROM AUTHOR]

Hydrolytically degradable poly(β‐thioether ester ketal) thermosets are synthesized via radical‐mediated thiol‐ene photopolymerization using three novel dialkene acyclic ketal monomers and a mercaptopropionate based tetrafunctional thiol. For all thermoset compositions investigated, degradation behavior is highly tunable based on the structure of the incorporated ketal and pH. Complete degradation of the thermosets is observed upon exposure to acidic and neutral pH, and under high humidity conditions. Polymer networks composed of cross‐link junctions based on acyclic dimethyl ketals degrade the quickest, whereas networks containing acyclic cyclohexyl ketals undergo hydrolytic degradation on a longer timescale. Thermomechanical analysis reveals low glass transition temperatures and moduli typical of thioether‐based thermosets. [ABSTRACT FROM AUTHOR]

The synthesis of novel phosphorus-containing telomers (P-telomers) was conducted via a solution-free UV-initiated telomerization process of butyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, and styrene, different phosphorus telogens (dimethyl phosphite (DMPh), dibutyl phosphite (DBPh), diphenyl phosphite (DPPh) or dibutyl phosphate (DBP)), and a radical photoinitiator-acylphosphine oxide (APO). The course of the UV-phototelomerization process was monitored by photo-DSC and the chemical structures of telomers were assessed by FTIR. Final UV-photocurable varnish compositions consisted of prepared P-telomer syrups, crosslinking monomer (pentaerythritol triacrylate; PETIA), and a radical UV-photoinitiator (α-hydroxyalkylphenone, HAP). The influence of P- telomers on the optical and mechanical features of coatings was investigated. Relatively the highest hardness and satisfactory scratch values, as well as water and solvent resistance, were observed for varnish based on DMPh-telomers. While the strongest adhesive bond to a glass substrate was reported for DPPh-telomers. It is worth pointing out that the P-telomers did not affect the gloss values of varnishes in comparison to the telomer-free reference sample. [ABSTRACT FROM AUTHOR]

A bifunctional diethylene glycol difuran acrylate (DEFA) and a trifunctional trimethylolpropane trifuran acrylate (TMFA) monomer for solid-state photopolymerization were synthesized from a biomass material, furfural. High molar extinction coefficients in the order of 104 indicate the good UV absorption properties of both monomers. The photopolymerization kinetics studies show that DEFA achieves a maximum polymerization rate (Rp) in 54 s and TMFA in 35 s without photoinitiators, and the maximum double bond conversion (DBC) reached 88% for DEFA and 78% for TMFA, which proves that they have high photosensitivity. The addition of the 2,4-dinitroaniline sensitizer increases the maximum DBC, but increases the maximum Rp markedly. The high crystallinity of DEFA and TMFA is prone to photodimerization and forms an amorphous polymer. Both the linear polyester from DEFA and the crosslinked polyester from TMFA have good thermal oxidation stability. Therefore, we developed a strategy to produce highly sensitive monomers for the application of photosensitive materials that polymerize quickly without photoinitiators and solvents. [ABSTRACT FROM AUTHOR]

Novel metal oxide/polymer composite photocatalysts prepared by photocuring with common metal oxide particles (ZnO or CeO2) and acrylic ester monomers have been investigated for the first time. Metal oxide particles were fully integrated with the acrylate polymer network based on the crosslink of poly ethylene glycol diacrylate (noted below as Poly-PEG) by photopolymerization upon mild light source (LED@405 nm) irradiation. The prepared metal/oxide composite showed excellent performance in the photodegradation of Acid Black dye (used as a benchmark pollutant) in an aqueous environment. Indeed, under UV lamp irradiation for 60 min, the degradation of Acid Black reached 59% and 56%, in the presence of 10 wt% ZnO/Poly-PEG and 3 wt% CeO2/poly PEG, respectively. Markedly, the new reported photocatalysts have offered much better performance over the conventional TiO2 photocatalytic material used as a control (39% degradation using 1 wt% TiO2/poly PEG). In turn, the new proposed metal oxide/polymer composites were further characterized by a range of analytical characterization methods, including the swelling test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), dynamic mechanical analysis (DMA), UV–visible diffuse reflectance spectroscopy, and electron spin resonance analysis. The results showed that the new photocatalysts demonstrated excellent water adsorption properties, high-temperature resistance, and excellent recyclability, which were very suitable for wide application and in line with the concept of green chemistry. [ABSTRACT FROM AUTHOR]

In this perspective, we explore the historical evolution, photochemical processes, and distinct utility of photoiniferter polymerization. We aim to provide a practical guide encompassing the selection of iniferter and monomer, coupled with the optimization of light wavelengths to conduct efficient photoiniferter polymerizations. We delve into the impact of iniferter structure on photophysical properties and the resulting polymerization behavior. Furthermore, we highlight ongoing research efforts employing photoiniferter polymerization, emphasizing its potential applications in cutting-edge areas of research such as 3D printing and the synthesis of ultra-high molecular weight polymers (≥ 106 g mol-1). Through this perspective, we aim to clarify both the fundamental principles and the practical considerations of photoiniferter polymerization, ultimately advancing its utility and paving the way for innovative applications in polymer science. [Display omitted] [ABSTRACT FROM AUTHOR]

Photopolymerizations of monomer methyl methacrylate being nanocomposite have been widely carried out because it has the advantage that it can improve the properties of the materials used. The purpose of this research was to study the synthesized characteristics of PMMA+ITO and PMMA+ITO+PE-b-PEG using the UV Curing method. The nanocomposites were synthesized with a variation of ITO concentrations were 5% w/t, 10% w/t, and 15% w/t. The characterization group functions using FTIR spectroscopy showed the loss of absorption peaks at wave numbers 3100 cm-1 and 1670 cm-1 at PMMA. The results of XRD characterization showed that effect addition of PE-b-PEG, peaks appeared around the 2θ 19°-28° area which was a typical peak for PE-b-PEG. the nanocomposite is an amorphous phase still dominated. Value of conductivity of nanocomposite PMMA addition of ITO with a concentration of 15% resulted in a nanocomposite with the highest conductivity value of 6.4068 x 10-7 S/m. [ABSTRACT FROM AUTHOR]

This study reports an ultra‐facile, economical, and environmentally friendly hydrogel synthesis method using renewable raw materials. The synthesis and photopolymerization of oleyl methacrylate (OM) and the epoxidized derivative of OM monomers are evaluated. In the first step, oleyl alcohol is esterified with methacryloyl chloride and then epoxidized via the Prilezhaev reaction. These monomers are used for hydrogel synthesis. For this purpose, they are polymerized with N‐isopropyl acrylamide, N,N‐methylene bis(acrylamide), or ethylene glycol dimethacrylate (EDGMA) via the photopolymerization technique. Novel hydrogels are successfully fabricated using a green process. Epoxidized OM‐based hydrogel achieves an excellent yield of 87.1%. Moreover, low‐energy UV irradiation and short reaction times reduces energy consumption. The thermal properties of the gels are also considered by differential scanning calorimetry (DSC) and thermogravimetric analysis techniques. DSC results reveal that the epoxidized OM‐based hydrogel exhibits a melting peak at 84.5 °C. The highest 5% weight loss temperature is obtained for the OM‐EDGMA copolymer as an indicator of thermal stability. [ABSTRACT FROM AUTHOR]

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The microfluidic production of Janus/Hecate polymer microfibers with well-defined interfaces from miscible phases is reported. The process offers tunability of the width and composition of each part of the fibers by controlling the flow rate and nature of the monomers in a single step. The enhanced performances of the fibers are outlined for the simultaneous removal of dyes of opposite charges using amphoteric Janus fibers. [ABSTRACT FROM AUTHOR]

Hierarchical patterns are widely found on the biological skins in nature and can provide unique functions to surfaces such as wettability, optical, and adhesive properties. Herein, a facile and robust strategy to generate the self‐wrinkling pattern on the surface of the photo‐curing coating is proposed, which comprises a crosslinking monomer, photoinitiator, and fluorinated copolymer as additive. The fluorinated copolymer, which contains fluorocarbon chains possessing low surface‐energy, tertiary amine as coinitiator, and anthracene in the side chain, can self‐assemble to the top layer for constructing the gradient photo‐crosslinking system. Upon the irradiation of ultraviolet (UV) light, the mismatch of shrinkage caused by the gradient photo‐crosslinking leads to the formation of wrinkles, the morphology of which can be regulated by monomer proportion, the content of fluorinated copolymer, and the thickness of the film. Taking the spatiotemporal advantages of light, the hierarchical patterns of wrinkle are generated by programmed exposure with photomask, which has potential applications in anti‐counterfeiting and encapsulation of light‐emitting diode (LED) chip for displaying. This strategy provides a rapid and universal alternative method to fabricate a hierarchical pattern of the surface. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Fast and well-controlled photoinduced atom transfer radical polymerization (photoATRP) in the organized medium of a bilayer activated by visible light under environmentally friendly mild aqueous conditions leads to polymers with predetermined molecular weight and low dispersity. The decisive parameter for photoATRP of monomers in the organized medium was their mobility and orientation with respect to the bilayer and the photoredox catalyst localized in the interstitial layer. [ABSTRACT FROM AUTHOR]

The distinct features of UV induced polymerization of epoxy-acrylate blends leading to the formation of simultaneous interpenetrating polymer networks (IPNs) have been studied. Different ratios of components within a prevailing content of an epoxy one have been used for the synthesis. Such a content of epoxy monomer is required to create a barrier preventing oxygen diffusion into a curing sample. It allows retardation of the well-known oxygen-inhibition effect, which acrylate monomers are susceptible to. Hence, the conduction of their polymerization in open-air conditions is possible. The proceeding of the polymerization reactions of acrylate (TEGDM) via free radical mechanism and of epoxy (UP-650D) via cationic one have been monitored by FTIR-spectroscopy. Namely, the conversion degrees have been calculated for double bonds of TEGDM and for epoxy groups of UP-650D respectively. A mixture of triphenylsulfonium hexafluorophosphate salts, which is capable of generating both free radical and cationic reactive species, have been used as a single photoinitiator for the formulations being investigated. Almost complete conversion of acrylate double bonds was reached after 60 min of UV irradiation irrespective of epoxy content. On the contrary, conversion of epoxy groups of aliphatic epoxy, which is known to be rather unreactive towards cationic photopolymerization, when mixed may be either higher or lower compared to the neat epoxy network. Such results are attributed to dual influence of acrylate network on the formation of epoxy one. Firstly, cationic polymerization of epoxy component is sensitized by acrylate macroradicals in terms of free radical promoted cationic polymerization. On the other hand, the mobility of epoxy macrocations is restricted by the rapid build-up of acrylate network. At the weight ratio of UP-650D and TEGDM 70/30 the sensitizing effect of acrylate is revealed to be dominant, so the given composition may be considered as optimal. Regardless of low conversion of epoxy groups, the content of the estimated gel fraction is high, and the epoxy component is found not to be leached in the process of extraction in acetone. Furthermore, physicomechanical properties of obtained UV-cured IPNs have been investigated. The results of the measurements, namely, impact resistance by the Gardner test, crosshatch adhesion test to different substrates (including silicon), and accelerated weathering test in a climatic chamber, show that all the samples exhibit good operational properties essential for effective protecting coatings of outdoor exposure. [ABSTRACT FROM AUTHOR]

Molecularly imprinted polymers (MIPs) are a promising technology for sensing specific analytes. Structured MIP-coated quartz crystal microbalance sensors were developed for the detection of bisphenol A (BPA) using 2-dimethylaminoethyl methacrylate (DMAEMA) as a functional monomer. A simple unidirectional rubbing technique and a soft lithographic technique were used to fabricate convex hemispherical and hierarchical hemispherical MIP patterns, including a planar MIP film as a control. The two structured MIP films exhibited relatively higher imprinting factors and sensitivities compared with the planar MIP film and the selectivity coefficients of the structured MIP films were slightly increased due to the MIP structuring effect. [ABSTRACT FROM AUTHOR]

Conductive polymers find key applications ranging from optoelectronics and OLEDs to conductive composite materials. The synthesis of conductive polymers from monomers, such as thiophene derivatives, pyrroles and aniline, mainly relies on oxidative polymerization, and the processing of so‐formed (insoluble) polymers is a major issue that needs to be addressed. In the present work, oxidative photopolymerization of 3,4‐ethylenedioxythiophene (EDOT) by visible light employing the metal‐free semiconductor graphitic carbon nitride (g‐CN) is presented. Two main reaction pathways based on g‐CN content are described, and the formation of processable oligo‐EDOT is demonstrated. [ABSTRACT FROM AUTHOR]

The photopolymerization process is a high-precision and efficient technology to obtain solid polymers starting from a photosensible liquid resin made of monomer units. This technology is widely used in Additive Manufacturing (AM) to produce objects whose size can fall within the range 10 − 5 − 10 0 m. The outstanding potentialities of this technology can be harnessed to tailor the structure of a polymeric material by controlling how the light-induced polymerization process is performed, typically by operating on subsequent layers forming the final object. The present research illustrates the chemical-physics phenomena involved in the photopolymerization and presents a multi-physics framework and the related governing equations. Its implementation within a computational framework is developed and several simulations demonstrating the influence of the AM printing setup on the final microstructure of the obtained polymer are presented. It is shown that photopolymerization-based AM technology allows us to finely tune the mechanical properties distribution within the material domain, enabling the material's architecture to be tailored to the application of interest. • Multi-physics model of layered photopolymerization. • Mechanics of polymers obtained through photopolymerization. • Numerical implementation of the photopolymerization process. • Numerical simulations. • Layer-interface characterization. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Introduction: Composite resins have excellent mechanical properties, including fast polymerization, aesthetic quality, easy handling, and the ability to adhere to the enamel surfaces. However, there are also some disadvantages from this material, one of them is residual monomers. Bulk-fill composite resins are available in sculptable (solid) and flowable (liquid) form. Most composite resin matrix is aromatic or aliphatic acrylates. Bis-GMA, UDMA, and TEGDMA are the matrix monomers that are commonly used but show a high cytotoxicity level. They also have poor mechanical properties such as wear resistance, hardness, tendency to change color, and may cause pulp reactions. Aim: The aim of this study was to investigate the number of residual monomers in bulk-fill sculptable and flowable composites in the submersion of 75% ethanol solution (10 minutes, an hour, and 24 hours). Methods: Sculptable and flowable composites were used in this study. Samples (4 mm thick, 5 mm diameter) were prepared and polymerized for 10 seconds with an intensity of 1025 mW / cm2 of a light emitted diode (LED). After the sample was made, each sample was immediately immersed in a 75% ethanol solution as an extraction liquid and stored in amber-colored bottles at room temperature. Samples were taken as many as 7 cc at intervals of 10 minutes, an hour, and 24 hours. Samples were analyzed by High-Performance Liquid Chromatography (HPLC). The data obtained were analyzed using the Kruskal-Wallis Test, Independent T-Test and Mann-Whitney Test at a significance level of p <0.05. Result: The amount of elusion remaining monomers of the bulk-fill flowable composite was higher than bulk-fill sculptable composite. UDMA composite of bulk fill flowable submersed in 75% ethanol solution for 24 hours was the highest among other monomers. Conclusion: Residual monomers eluted inside bulk-fill composite resins in all time periods and the amount of eluted monomers increases with time. [ABSTRACT FROM AUTHOR]

Single-particle fluorescence imaging is used to monitor dynamic processes that occur during patterned photopolymerization of liquid-crystalline monomers. A spatial gradient of chemical potential can be created at the border of bright and dark regions by structured illumination in the photopolymerization process, leading to mutual diffusion of polymers and monomers. Analysis of the fluorescence from single quantum dots doped into the monomers at minute concentrations enables visualization of highly directional flow from the illuminated region where the photopolymerization proceeds toward a masked unpolymerized region. This directional mass flow causes flow-induced orientation of the polymers that is subsequently fixed by completion of the polymerization reaction, resulting in a mesoscopic aligned area of the polymer film. Polymerization: Bringing molecules into line The light-induced processes that enable the alignment of long molecules have been described by scientists in Japan. The long chain of molecules that form a polymer is often tangled and disorganized. However, in so-called liquid-crystalline polymers, the molecular chains are straight. Aligning these chains with each other creates materials useful for photonic and biomedical applications. Current alignment techniques are slow and complex or require the addition of a dye, which alters the material's properties. Martin Vacha and Atsushi Shishido from the Tokyo Institute of Technology (in Tokyo and Yokohama) and co-workers used single-particle fluorescence imaging to understand the molecular processes that occur during patterned photopolymerization, a novel method for aligning liquid-crystalline polymers which avoids the disadvantages above. They show that optical illumination induces chemical differences between the bright and shadowed regions, which helps alignment. Single-particle fluorescence imaging is used to monitor dynamic processes that occur during patterned photopolymerization of liquid-crystalline monomers. Spatial gradient of chemical potential created at the border of bright and dark regions by structured illumination leads to mutual diffusion of polymers and monomers. Fluorescence of single quantum dots doped into the monomers visualizes highly directional mass flow from the illuminated region where the photopolymerization proceeds toward a masked unpolymerized region. The flow-induced orientation of the polymers is subsequently fixed by completion of the polymerization reaction, resulting in a mesoscopic aligned area of the polymer film. [ABSTRACT FROM AUTHOR]

The global market for 3D printing materials has grown exponentially in the last decade. Today, photopolymers claim almost half of the material sales worldwide. The lack of sustainable resins, applicable in vat photopolymerization that can compete with commercial materials, however, limits the widespread adoption of this technology. The development of "green" alternatives is of great importance in order to reduce the environmental impact of additive manufacturing. This paper reviews the recent evolutions in the field of sustainable photopolymers for 3D printing. It highlights the synthesis and application of biobased resin components, such as photocurable monomers and oligomers, as well as reinforcing agents derived from natural resources. In addition, the design of biologically degradable and recyclable thermoset products in vat photopolymerization is discussed. Together, those strategies will promote the accurate and waste‐free production of a new generation of 3D materials for a sustainable plastics economy in the near future. [ABSTRACT FROM AUTHOR]

• Three aromatic monofunctional methacrylates are evaluated as high refractive index diluents for the formulation of radiopaque bulk-fill composites. • Photopolymerization kinetics of these monomers are investigated by photo-DSC. • Bulk-fill composites based on the new diluent monomers exhibit improved mechanical properties, reduced shrinkage force and lower water sorption in comparison with a reference composite containing TEGDMA. To evaluate high refractive index methacrylates as diluents for the formulation of radiopaque esthetic bulk-fill composites. 2-(4-Cumylphenoxy)ethyl methacrylate 1 , 2-(2-phenylphenoxy)ethyl methacrylate 2 and 2-[2-(2-phenylphenoxy)ethoxy]ethyl methacrylate 3 were synthesized and characterized by 1H NMR spectroscopy. The reactivity of each monomer was studied using photo-DSC. Bulk-fill composites based on monomers 1–3 were formulated. Translucency (before and after light cure) was measured using a spectrophotometer. The depth of cure and the water sorption of these materials were determined according to ISO 4049. The flexural strength and modulus of elasticity were measured using a three-point bending setup, according to ISO 4049. The shrinkage force was assessed based on a method described by Watts et al. using a universal testing machine. Monomers 1–3 were easily synthesized in two steps. They exhibit a low viscosity and a high refractive index (1.553–1.573). Monofunctional methacrylates 1–3 were found to be more reactive than triethylene glycol dimethacrylate (TEGDMA). Bulk-fill composites based on these monomers were successfully prepared. They exhibit a high depth of cure and excellent esthetic properties (low transparency). These composites provide higher flexural modulus as well as lower water sorption than a corresponding material based on TEGDMA. Methacrylates 1 and 3 are particularly interesting as they led to composites showing lower shrinkage force. Methacrylates 1–3 are promising diluents for the formulation of highly esthetic radiopaque bulk-fill composites. [ABSTRACT FROM AUTHOR]

UV curing of photopolymerizable monomers, like (meth)acrylates, has been utilized for coatings for more than half a century and more recently in further developed areas such as tissue engineering. However, these monomers have major disadvantages, e.g., high irritancy and cytotoxicity, which leads to limited use in tissue engineering regarding health issues. Vinyl esters (VE) and vinyl carbonates (VC) can compete with (meth)acrylates in terms of material properties and have significantly lower toxicity, but lack in cost efficient synthesis methods. The purpose of this communication is to establish new pathways to overcome this drawback. It was shown that VEs can be synthesized either by vinyloxy trimethylsilane or by acetaldehyde in excellent yields. Moreover, a new method to synthesize vinyl chloroformate as precursor for VCs in lab scale was evolved by a catalyzed reaction of vinyloxy trimethylsilane with a phosgene solution. Finally, the cytotoxicity tests showed auspicious results. [ABSTRACT FROM AUTHOR]

Based on the addition reaction of hydroxyl groups and the isocyanate groups in the bi‐functional monomer acroyloxyethyl isocyanate (AOI), two novel self‐initiating ultraviolet (UV)‐curable acrylate monomers were synthesized from benzoin and 2‐hydroxy‐4′‐(2‐hydroxyethoxy)‐2‐methylpropiophenone (commercial‐available Irgacure® 2959), and the products were denoted as Benzoin‐AOI and 2959‐AOI, respectively. The chemical structures of the products were confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The UV–visible absorption spectrum showed that the self‐initiating acrylates exhibited similar maximum absorption wavelengths to both benzoin (250 nm) and Irgacure® 2959 (270 nm). When the products were continually exposed to a mercury lamp, the maximum absorption peak gradually blue shifted, showing that the products decomposed under the UV radiation. The photo differential scanning calorimetry (Photo‐DSC) analysis showed that the self‐initiating monomers could initiate the polymerization of 1,6‐hexanediol diacrylate (HDDA) as quickly as the original photo‐initiator, and the efficiency of Benzoin‐AOI was slightly lower than that of benzoin, while for 2959‐AOI, the efficiency remained stable after being linked to the AOI moiety. The cytotoxicity assay against fibroblasts cell line L929 showed that 2959‐AOI exhibited lower cytotoxicity at low dosages but higher cytotoxicity at high dosages compared to Irgacure® 2959 after the introduction of the AOI structure. [ABSTRACT FROM AUTHOR]

In this study, we fabricated liquid crystal polymer networks (LCNs) containing a large amount of crosslinker by scanning wave photopolymerization, and examined the effect of crosslinker concentration on molecular alignment behavior. Samples with different crosslinker concentrations were photopolymerized by unidirectionally scanning ultraviolet light, resulting in LCN films with uniaxial molecular alignment. The LCN films obtained from the compositions of only monomer or monomer and crosslinker had mesogens aligned in parallel to the light scanning direction. Moreover, the LCN films with high crosslinker concentrations were able to maintain their initial molecular alignment after repeated heating cycles. [ABSTRACT FROM AUTHOR]