Exploring new initiation functionalities is critical for the design of efficient photoinitiators applied in two-photon polymerization. In this paper, we present a facile and effective synthesis strategy to construct silyl-based two-photon initiators (2PIs) containing nitro groups as electron acceptors, alkylamines as electron donors and double bonds as conjugation bridges. Steady-state absorption, time-resolved fluorescence, and ns-transient absorption were employed to quantitatively investigate the photo-physics and -chemistry of the 2PIs. The results showed that the photophysical and photochemical behavior of these 2PIs is marginally affected by the introduction of a silyl group, but strongly depends on solvent polarity. The nonlinear absorption spectra over a broad spectral range were determined via two-photon-induced fluorescence, revealing maximum two-photon cross sections of ∼90 GM. In two-photon polymerization structuring tests, the 2PIs can be employed to build fine 3D microstructures with a resolution of ∼280 nm. The acrylate formulations containing novel 2PIs exhibit a comparable threshold energy and ideal processing windows as commercial photoresists IP-L, which have been specifically designed for Nanoscribe's laser lithography systems.

Simultaneous thiol-based hybrid photopolymerization is an efficient and versatile tool to prepare interpenetrating polymeric networks. A highly active photoinitiator is essential for an efficient simultaneous hybrid reaction. In this paper, several unimolecular photoinitiators, which contain thioxanthone derivatives as chromophores as well as free radical generators, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as a latent alkaline species, were straightforwardly prepared in two steps. The photolysis study indicated that under 405 nm LED light irradiation, the photoinitiators can produce free radicals and a strong base simultaneously via a photodecarboxylation mechanism. The generated active species are highly efficient in catalyzing thiol–yne–epoxy hybrid polymerization without post-exposure baking and the properties of the hybrid network can be tailored by adjusting the compositional ratios of the formulations. The photocured materials using unimolecular photoinitiators exhibit superior thermal and mechanical properties compared to those prepared using a bimolecular initiation system from the literature. The presented strategy to realize simultaneous thiol–yne–epoxy hybrid photopolymerization shows potential for the fabrication of optical devices with enhanced refractive index and improved mechanical properties.

Although photopolymerization has been versatile in various applications, photopolymerization of thick materials still remains a great challenge due to the light-intensity gradient. In this paper, we report a facile and generic method to realize deep photopolymerization using upconversion nanoparticle (UCNP)-assisted photochemistry. Compared to the reported photocuring depth of several millimeters, 13.7 cm of photopolymerization depth combined with about 60% of double bond conversion is obtained with optimal parameters. The thermal effect during UCNP-assisted photopolymerization is comparable to or weaker than that of some reported frontal photopolymerization used for the preparation of dental filling materials and functional polymer composites. The photocured materials using UCNPs as internal lamps exhibit a similar nanoindentation hardness and reduced modulus to those cured under traditional blue LED light. The presented strategy shows great potential applications in ultra-high density data storage and the preparation of biomaterials.

In this paper, a facile, economical and environmentally friendly synthetic method was developed to fabricate a Ag nanoparticle (NP) decorated graphene (GR/TA/Ag) composite with tannic acid (TA) as a reducing agent and stabilizing agent. The GR/TA/Ag composite was fully characterized using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that Ag NPs with diameters of up to 6 nm were homogeneously and uniformly deposited on graphene sheets. With an increasing concentration of AgNO3 used for immersion, the amount of Ag NPs loaded kept increasing without aggregation or deformation. The antibacterial properties of the GR/TA/Ag composite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 via both the disk diffusion method and the shaking flask method. The disk diffusion method results showed that the synthesized GR/TA/Ag composite had great release antibacterial properties owing to the loading of Ag NPs. In addition, the presence of TA gave the composite good non-release antibacterial properties, based on the results of the shaking flask method. The ingenious combination of the release-killing capabilities of Ag NPs and the contact-killing capabilities of TA bestow two-level antibacterial activity on the GR/TA/Ag composite, promoting the GR/TA/Ag composite as part of a new generation of powerful antibacterial agents with promising applications.

•The synthesized polyimides with double bond end groups showed an outstanding solubility, and possessed excellent solution processability.•The synthesized polyimides could be used to prepare UV-curable coatings.•The UV cured coatings exhibited excellent performances, such as favorable thermal stability, higher optical transparency and lower moisture uptakes.The fluorinated polyimides with double bond end groups (G-FPIs) based on 4,4′-(hexafluoroisopropylidene) diphthalic anhydride, 4,4′-(hexafluoroisopropylidene) dianiline, 4-aminobenzoic acid and glycidyl methacrylate were synthesized via a typical two-step imidization method. The structure and properties of G-FPIs were characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1HNMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It was determined that all G-FPIs were the amorphous phase and easily soluble in many polar organic solvents, and the G-FPIs had high glass-transition temperature (Tg). Then, UV-curable coatings were prepared from G-FPIs, and the properties were evaluated by real-time fourier transform infrared (RTIR), thermogravimetric analysis (TGA), UV–vis spectroscopy, water contact angle and water absorption test. Results showed that these coatings possessed favorable double bond conversion, excellent thermal stability, higher optical transparency and lower moisture uptakes. Moreover, the coatings exhibited good hardness and excellent gloss. Due to the outstanding combination properties, these UV-cured coatings based on G-FPIs could be considered as potential candidates for photoelectric, microelectronic and aerospace materials.

•We synthesized a series of UV-curable self-healing oligomers based on quadrupolar hydrogen bonding.•The healing performance of UV-curable self-healing coatings was fast and efficient, scratch within 3–4 μm was almost completely healed in 1 min by hot air gun.•The healing efficiency of UV-curable self-healing coatings can exceed 90% with the coating thickness of 110 μm.A novel UV-curable self-healing oligomer was designed on the basis of a quadrupolar hydrogen bond system. The oligomer is formed by reacting a mixture of a hydrogen bonding group and a photosensitive monomer with three-arm polyols. The structure was identified using 1H NMR and the real-time FTIR was used to observe the conversion of double bonds. The self-healing property was monitored by optical microscopy and atomic force microscope, and the gloss induced by damaging and healing processes was tested using a glossmeter. Furthermore, a thermogravimetric analyzer was used to test the thermostability. The healing performance was considerably improved with the increasing content of the ureido-pyrimidone dimer. The results revealed that the reversibility of the quadrupolar hydrogen bond system is beneficial to the healing capacity.

Two kinds of UV-curable polyurethane acrylates (PCDL-H-PUA and PCDL-P-PUA) were synthesized starting with polycarbonate diols (PCDL), isophorone diisocyanate and dimethylolpropionic acid and terminated with hydroxyethyl methacrylate or pentaerythritol triacrylate to impart mono-methacrylate or tri-acrylate end-group functionality, respectively. The structures and properties of the products were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis. The average molecular weights were between 7500 and 9300 g/mol, and the thermal properties of the products were excellent. The influence of the functionality of the end-capping functional group on the UV-curing behavior was investigated using real-time spectroscopy. Results showed that curing rate and conversion of PCDL-P-PUA were higher than those of PCDL-H-PUA, and the final double bond conversion of the polymers reached 95 %. PCDL-H-PUA and PCDL-P-PUA were applied to negative photoresists as the main film resin. The resolution of the optimal photoresist reached 40 µm.

Noncovalent surface modification has been proved to be one of the effective strategies for enhancing the properties of multi-walled carbon nanotubes (MWCNTs). When a non-covalent modification method is appropriately designed, novel opportunities for better performance of CNTs can be expected. In this paper, a novel kind of branched amphiphilic photo-sensitive and electro-active copolymer (BP(VCz/VM-alt-MA); BPVCM) was synthesized through a simple one-pot free radical copolymerization with 7-(4-vinylbenzyloxy)-4-methyl coumarin (VM), maleic anhydride (MA), 4-vinylbenzyl thiol (VBT) and 9-(4-vinylbenzyl)-9H-carbazole (VCz) as monomers. The copolymer BPVCM can self-assemble into homogeneous spherical micelles along the side-walls of MWCNTs and efficiently disperse MWCNTs in aqueous solution. In addition, the photosensitive coumarin groups of the copolymer chain undergo crosslinking under UV-irradiation, which leads to the encapsulation of MWCNTs in the crosslinked micelles and greatly improves the stability of the obtained MWCNT suspension. More interestingly, the electroactive carbazole moieties of the BPVCM–MWCNT composites could polymerize via an electrochemical polymerization method and form a MWCNT based conducting coating on the modified glassy carbon electrode (GCE), which eventually increases the number of electroactive sites and significantly accelerates the electron transfer. This novel preparation method permits us to obtain carbon nanotube hybrids exhibiting high water-dispersibility and stability while preserving their outstanding electrical properties, and would be valuable for construction of microelectronics and electrochemical sensors.

A series of biobased UV-curable antibacterial resins were synthesized through modifying tannic acid (TA) with varied amount of glycidyl methacrylate (GMA). The obtained TA-based methacrylates exhibited good film-forming property and can be cross-linked under UV irradiation. Thus, antibacterial functionalities can be tethered in the coating matrix, eliminating the loss of antibacterial ingredients. The antibacterial properties of resins and corresponding coatings against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were tested. The resins with high content of phenolic hydroxyl groups retained strong antibacterial ability while the ones with a relatively low content of phenolic hydroxyl groups did not, which indicated that the antimicrobial effects of TA greatly depended on the content of phenolic hydroxyl groups. The applications of UV-curable antibacterial resins in coatings were also studied. The cured coatings of TA-G5 resins with the highest content of phenolic hydroxyl groups exhibited the highest antibacterial activity with 5 log reduction. The basic properties of UV-cured coatings were also fully characterized, and the results demonstrated that the novel UV-curable resins had potential applications in UV-curable antibacterial coatings.

•Biorenewable tannic acid-based hyperbranched methacrylates (TAHAs) were synthesized.•TAHAs were applied to AESO based UV curable coatings as efficient toughening agents.•Hybrid UV-curable coatings produced good performance and high biorenewable content.With a view to developing high performance UV curable coatings with high renewable contents, acrylated epoxidized soybean oil (AESO) was combined with a novel kind of biorenewable tannic acid-based hyperbranched methacrylates (TAHAs). The TAHAs were synthesized by ring-opening reaction of glycidyl methacrylate (GMA), glycidyl ester of Versatic acid (CE10) and natural tannic acid (TA). The epoxy groups of GMA and CE10 were involved in the ring-opening reaction with the hydroxyl groups of TA while residual methacrylate groups can carry out photopolymerization. By controlling the ratio of GMA and CE10, TAHAs with varying degree of methacrylate groups have been prepared. The synthesized TAHAs were formulated into acrylated epoxidized soybean oil (AESO) based UV curable coatings to produce the biorenewable materials based UV curable coatings. The effects of TAHAs on AESO coated film properties of pendulum hardness, flexibility and adhesion were investigated. Mechanical properties, thermal properties and biodegradability of the cured films were also evaluated. With the incorporation of TAHAs, the hardness, adhesion, tensile strength of the cured coating films were remarkably improved, which were attributed to the unique structure of hyperbranched methacrylates. Meanwhile, the biorenewable content was not greatly decreased due to the biorenewable character of tannic acid in TAHAs. These results showed that TAHAs as efficient toughening agents could produce UV-curable coatings of balanced coating performance with reasonably high biorenewable content. Moreover, the environment degradability of AESO-based cured films was also enhanced after the addition of TAHAs.

Noncovalent surface modification has been proved to be one of the effective strategies for enhancing the properties of multi-walled carbon nanotubes (MWCNTs). When a non-covalent modification method is appropriately designed, novel opportunities for better performance of CNTs can be expected. In this paper, a novel kind of branched amphiphilic photo-sensitive and electro-active copolymer (BP(VCz/VM-alt-MA); BPVCM) was synthesized through a simple one-pot free radical copolymerization with 7-(4-vinylbenzyloxy)-4-methyl coumarin (VM), maleic anhydride (MA), 4-vinylbenzyl thiol (VBT) and 9-(4-vinylbenzyl)-9H-carbazole (VCz) as monomers. The copolymer BPVCM can self-assemble into homogeneous spherical micelles along the side-walls of MWCNTs and efficiently disperse MWCNTs in aqueous solution. In addition, the photosensitive coumarin groups of the copolymer chain undergo crosslinking under UV-irradiation, which leads to the encapsulation of MWCNTs in the crosslinked micelles and greatly improves the stability of the obtained MWCNT suspension. More interestingly, the electroactive carbazole moieties of the BPVCM–MWCNT composites could polymerize via an electrochemical polymerization method and form a MWCNT based conducting coating on the modified glassy carbon electrode (GCE), which eventually increases the number of electroactive sites and significantly accelerates the electron transfer. This novel preparation method permits us to obtain carbon nanotube hybrids exhibiting high water-dispersibility and stability while preserving their outstanding electrical properties, and would be valuable for construction of microelectronics and electrochemical sensors.