Synthesis and Properties of a Photopolymerizable Carbene-Mediated Poly Phosphinate Flame Retardant by Carbene Polymerization

A novel photopolymerizable poly phosphinate (poly ethyl (4-acrylamidebenzyl)­phosphinate, P-NH-AC) flame retardant was synthesized by a carbene polymerization and characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and gel permeation chromatography (GPC). The effect of P-NH-AC on the kinetics of photopolymerization, thermal stability, combustion behaviors, and physical and mechanical properties of the UV-cured materials were investigated by real-time infrared spectroscopy (RT-IR), thermogravimetric analysis (TGA), thermogravimetric analysis/infrared spectrometry (TGA-IR), the limiting oxygen index (LOI), and the cone calorimetric test (CCT). For the systems with P-NH-AC, the thermal stability was improved with the increase of the P-NH-AC; however, the final residue of all systems was low. The addition of 5% P-NH-AC increased the LOI from 29.0 to 32.0. The addition of P-NH-AC significantly decreased the heat release rate (HRR), total heat release (THR), and total smoke production (TSP) of the resin. Moreover, P-NH-AC can also improve physical and mechanical properties of the materials

Compositional Gradients in Siloxane Copolymers by Photocontrolled Surface Segregation

We demonstrate how to tune the surface chemistry and properties of copolymers obtained by the photopolymerization of polyoxyethylene (meth)­acrylic monomers and a low polarity siloxane comonomer which spontaneously migrates to the free surface. By controlling the photopolymerization conditions, such as the light gradient through the thickness of the film and selecting the proper monomer functionality, it is possible to optimize and photoenforce the surface segregation of the siloxane comonomer. Photocured films containing the same amount of siloxane component (1 wt %) can exhibit a surface energy ranging from 42 to 22 mN m^–1 depending on the process conditions. XPS and AFM analyses confirm that polymers with a compositional gradient are obtained and that the surface segregation can be finely photocontrolled. Photopolymerization is thus proven to be a facile, single step method for generating gradient films and for independently and simultaneously tune their surface and bulk properties

Photocured Materials with Self-Healing Function through Ionic Interactions for Flexible Electronics

Photocured materials with self-healing function have the merit of long lifetime and environmentally benign preparation process and thus find potential applications in various fields. Herein, a novel imidazolium-containing photocurable monomer, (6-(3-(3­(2-hydroxyethyl)-1<i>H</i>-imidazol-3-ium bromide)­propanoyloxy)­hexyl acrylate, IM-A), was designed and synthesized. Self-healing polymers were prepared by fast photocuring with IM-A, isobornyl acrylate, 2-(2-ethoxyethoxy)­ethyl acrylate, and 2-hydroxyethyl acrylate as the monomers. The mechanical and self-healing properties of the polymers were tuned by varying the contents of IM-A and other monomers. The as-prepared self-healing polymer IB7-IM5 exhibited a tensile strength of 3.1 MPa, elongation at break of 205%, healing efficiency of 93%, and a wide healing temperature range from room temperature to 120 °C. The self-healing polymer was also employed as a flexible substrate to fabricate a flexible electronic device, which could be healed and completely restore its conductivity after the device was damaged

Synthesis and Characterization of Alkali-Soluble Hyperbranched Photosensitive Polysiloxane Urethane Acrylate

A novel alkali-soluble hyperbranched photosensitive polysiloxane urethane acrylate (AHBPSUA) was synthesized by using hyperbranched polyesters, hydroxyl-terminated polysiloxane, dimethylolpropionic acid, isophorone diisocyanate, and 2-hydroxyethyl acrylate as raw materials, and its structure was characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and ¹H nuclear magnetic resonance spectroscopy. It was found that AHBPSUA possessed good compatibility with a number of acrylate monomers. The effect of photoinitiators and monomers on the photopolymerization kinetics of AHBPSUA was investigated by real-time infrared spectroscopy (RT-IR). The results showed that AHBPSUA could rapidly photopolymerize under UV irradiation in the presence of a photoinitiator and the optimal concentration of the photoinitiator (Darocur 1173) was determined as 0.1 wt %. The resin of AHBPSUA with common acrylic monomers exhibited a high polymerization rate and double-bond conversion and could form a regular image under UV irradiation through a patterned mask. The AHBPSUA system could dissolve in 1 wt % sodium carbonate solution easily and completely, and the cured coating film of the AHBPSUA system possessed excellent flexibility, toughness, and heat resistance

Photocured Materials with Self-Healing Function through Ionic Interactions for Flexible Electronics

Photocured materials with self-healing function have the merit of long lifetime and environmentally benign preparation process and thus find potential applications in various fields. Herein, a novel imidazolium-containing photocurable monomer, (6-(3-(3­(2-hydroxyethyl)-1<i>H</i>-imidazol-3-ium bromide)­propanoyloxy)­hexyl acrylate, IM-A), was designed and synthesized. Self-healing polymers were prepared by fast photocuring with IM-A, isobornyl acrylate, 2-(2-ethoxyethoxy)­ethyl acrylate, and 2-hydroxyethyl acrylate as the monomers. The mechanical and self-healing properties of the polymers were tuned by varying the contents of IM-A and other monomers. The as-prepared self-healing polymer IB7-IM5 exhibited a tensile strength of 3.1 MPa, elongation at break of 205%, healing efficiency of 93%, and a wide healing temperature range from room temperature to 120 °C. The self-healing polymer was also employed as a flexible substrate to fabricate a flexible electronic device, which could be healed and completely restore its conductivity after the device was damaged

Photocured Materials with Self-Healing Function through Ionic Interactions for Flexible Electronics

Photocured materials with self-healing function have the merit of long lifetime and environmentally benign preparation process and thus find potential applications in various fields. Herein, a novel imidazolium-containing photocurable monomer, (6-(3-(3­(2-hydroxyethyl)-1<i>H</i>-imidazol-3-ium bromide)­propanoyloxy)­hexyl acrylate, IM-A), was designed and synthesized. Self-healing polymers were prepared by fast photocuring with IM-A, isobornyl acrylate, 2-(2-ethoxyethoxy)­ethyl acrylate, and 2-hydroxyethyl acrylate as the monomers. The mechanical and self-healing properties of the polymers were tuned by varying the contents of IM-A and other monomers. The as-prepared self-healing polymer IB7-IM5 exhibited a tensile strength of 3.1 MPa, elongation at break of 205%, healing efficiency of 93%, and a wide healing temperature range from room temperature to 120 °C. The self-healing polymer was also employed as a flexible substrate to fabricate a flexible electronic device, which could be healed and completely restore its conductivity after the device was damaged

Synthesis and characterization of photosensitive-fluorosilicone–urethane acrylate prepolymers

<div><p>Two kinds of novel photosensitive-fluorosilicone–urethane acrylate prepolymers (Si-F15-IPDI-HEA/Si-F6-IPDI-HEA) were synthesized and characterized. Si-F15-IPDI-HEA and Si-F6-IPDI-HEA were able to form homogeneous mixtures with a number of acrylate monomers. Formulations with these prepolymers with common acrylic monomers exhibited high-polymerization rates and final double-bond conversion over 90% after irradiation for 60 s. It was found the final conversion decreased with the increase of the functionality of the monomer. The influence of the monomer and prepolymers on the properties of the UV-cured films was systematically studied. Thermostability property along with mechanical performance was improved with the increase of the functionality of monomers and prepolymers. A decrease of water absorption was also observed through water contact angle measurements. The UV-cured films of Si-F15-IPDI-HEA and Si-F6-IPDI-HEA possessed an excellent adhesion on the PU and PVC leather, providing a potential application in leather industry as a finishing and coating agent.</p></div

Synthesis and Properties of Photosensitive Silicone-Containing Polyurethane Acrylate for Leather Finishing Agent

A photosensitive silicone-containing polyurethane acrylate prepolymer (Si-IPDI-HEA) was synthesized and characterized adequately by FTIR, ¹H NMR, and GPC analyses. The effect of the monomers on the photopolymerization kinetics of Si-IPDI-HEA was investigated by real-time infrared spectroscopy (RT-IR). The results showed that the resin of Si-IPDI-HEA with common acrylic monomers exhibited a high polymerization rate and double-bond conversion. The influence of the monomer and silicone on the microstructure and properties of the UV-cured film also was systematically studied. It was found that, with the increase of the functionality of the monomer, the thermostability, <i>T</i>_g, hardness, tensile strength, tensile modulus, and dispersion surface energy of the UV-cured film were increased, whereas the contact angle and elongation at break were decreased. The introduction of silicone into the prepolymer could enhance the thermostability of the UV-cured film, and reduce the dispersion surface energy by the change of the microstructure. More importantly, the leather finishing agent containing Si-IPDI-HEA has excellent comprehensive performance and potential application in the leather finishing agent

Both Complexity and Location of DNA Damage Contribute to Cellular Senescence Induced by Ionizing Radiation

<div><p>Persistent DNA damage is considered as a main cause of cellular senescence induced by ionizing radiation. However, the molecular bases of the DNA damage and their contribution to cellular senescence are not completely clear. In this study, we found that both heavy ions and X-rays induced senescence in human uveal melanoma 92–1 cells. By measuring senescence associated-β-galactosidase and cell proliferation, we identified that heavy ions were more effective at inducing senescence than X-rays. We observed less efficient repair when DNA damage was induced by heavy ions compared with X-rays and most of the irreparable damage was complex of single strand breaks and double strand breaks, while DNA damage induced by X-rays was mostly repaired in 24 hours and the remained damage was preferentially associated with telomeric DNA. Our results suggest that DNA damage induced by heavy ion is often complex and difficult to repair, thus presents as persistent DNA damage and pushes the cell into senescence. In contrast, persistent DNA damage induced by X-rays is preferentially associated with telomeric DNA and the telomere-favored persistent DNA damage contributes to X-rays induced cellular senescence. These findings provide new insight into the understanding of high relative biological effectiveness of heavy ions relevant to cancer therapy and space radiation research.</p></div

Synthetic Strategy and Performances of a UV-Curable Poly Acryloyl Phosphinate Flame Retardant by Carbene Polymerization

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