Tuning gradient property and initiating gradient photopolymerization of acrylamide aqueous solution of a hydrosoluble photocleavage polysiloxane‐based photoinitiator

A novel hydrosoluble photocleavage polysiloxane photoinitiator W‐Si‐HHMP₂ used for preparing a gradient polymer was synthesized on the basis of 2‐hydroxy‐1‐[4‐(2‐hydroxyethoxy)phenyl]‐2‐methyl propan‐1‐one (HHMP) and aminopolysiloxane. The water solubility of the photoinitiator, the kinetics of photopolymerization, and the self‐floating ability were investigated. This photoinitiator shows relatively good solubility in water and excellent photoinitiating efficiency, and has good floating capability due to lower surface tension and energy of polysiloxane. More importantly, it is proved that the gradient polymer with gradient molecular weight was obtained by controlling the concentration gradient of W‐Si‐HHMP₂ and presented an excellent yellowing resistance. The enrichment of W‐Si‐HHMP₂ on the surface caused by its good self‐floating ability can decrease the dispersion surface energy of gradient polymer film and generate a more hydrophobic surface. The W‐Si‐HHMP₂ can efficiently initiate gradient photopolymerization to prepare gradient materials and has a great potential application in gradient materials. Copyright © 2014 John Wiley & Sons, Ltd.     

Gradient polymer networks formed by photopolymerization with self‐floating polysiloxane‐containing nanogel

Polysiloxane‐containing nanogels can be used as a fast, convenient and environmentally friendly method to control gradient photopolymerization and to obtain gradient polymer network because of its self‐floating feature. The chain length of polysiloxane is a key factor that influences the self‐floating capability of the polysiloxane‐containing nanogel. This paper reports a series of nanogels compositions synthesized with methacrylate‐modified polysiloxanes with different chain lengths, urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) at a molar ratio of 10:20:70 in the presence of a thiol chain transfer agent. The effect of polysiloxane chain length on self‐floating capability of the nanogel and gradient polymer network was researched. The results show that polysiloxane chain length is the main driving force for the self‐floating capability of the nanogels. The nanogel with long polysiloxane chain length exhibits good self‐floating capability in the monomer–polymer matrix because of the lower surface tension of polysiloxane. Furthermore, the gradient polymer network containing the nanogel with long polysiloxane chain length presents lower dispersion surface energy and greater hardness and thermostability. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and characterization of copolymerizable one‐component type II photoinitiator

A copolymerizable one‐component Type II photoinitiator (CMEBP), based on 4‐hydroxybenzophenone (HBP), epichlorohydrin, morpholine, and acryloyl chloride, was synthesized and its structure was confirmed by ¹H‐NMR. The properties of CMEBP were investigated with UV spectroscopy and photo‐differential scanning calorimetry (photo‐DSC). The maximum of UV absorption red‐shifted significantly compared to benzophenone (BP). Photopolymerization results of tripropylene glycol diacrylate (TPGDA) indicated that CMEBP had larger maximum rate of polymerization than that of BP/triethanolamine (TEOHA) and HBP/triethylamine (TEA), larger final double bond conversion than that of HBP/TEA, but lower than that of BP/TEOHA. The rate of polymerization, final conversion increased and the induction period shortened with increase in CMEBP concentration. Copyright © 2008 John Wiley & Sons, Ltd.     

One‐component photoinitiator based on benzophenone and sesamol

A new benzodioxole derivative, 4‐(1,3‐benzodioxol‐5‐yloxy) benzophenone (BPBDO), based on benzophenone and sesamol was precisely synthesized, and it can be used as a 1‐component type II photoinitiator. Elementary analysis, atmospheric pressure chemical ionization mass spectrometry, ¹H nuclear magnetic resonance, and ¹³C nuclear magnetic resonance studies revealed that the molecular structure of BPBDO consisted of both benzophenone (BP) and benzodioxole (BDO) structures. The laser flash photolysis experiments and electron spin resonance test indicated that the process of radicals generated from BPBDO after irradiation was similar to 3 processes of ethyl 4‐dimethylaminobenzoate and BP. The kinetics of photopolymerization of the photoinitiator was also studied by real‐time infrared spectroscopy. The oxygen content, light intensity, and viscosity of the monomer affected the decomposition (R_d) and polymerization rate, and the final double bond conversion was also studied. All the results suggest that BPBDO is a 1‐component photoinitiator that is an efficient photoinitiator for free radical polymerization. In contrast to typical dual‐component photoinitiators, eg, BP/ethyl 4‐dimethylaminobenzoate or BP/BDO, BPBDO does not require an additional amine coinitiator for the initiation and is applicable in nonamine resin systems.     

Synthesis and characterization of multiarm (Benzoin-PS)m-polyDVB star polymer as a polymeric photoinitiator for polymerization of acrylates and methacrylates

In this study, a new benzoin-based multi-arm star polymer was synthesized by using ATRP, and characterization was achieved by spectrophotometric and chromatographic methods. Obtained multiarm (Benzoin-PS)_m-polyDVB star polymer was employed as a polymeric photoinitiator for polymerization of methacrylates and acrylates. Photophysical properties of this initiator were determined by fluorescence and phosphorescence measurements, the phosphorescence lifetime was calculated as 29 ms hence the lowest triplet state nature was n-π* character, and laser flash photolysis technique was additionally used to get more information about triplet state and triplet lifetime which was calculated as 1.34 ms. Photokinetics of difunctional acrylate such as HDDA was studied with a multi-arm (Benzoin-PS)_m-polyDVB star polymeric initiator using Photo-DSC.     

Synthesis of New Nitro‐Furan and Nitro‐Thiophene Derivatives from (Chlorocarbonyl) Phenyl Ketene

Nitro‐aromatic compounds are used in many human enteropathogenic bacterial infections without causing an increase in the plasmidial antibiotic resistance of the aerobic Gram‐negative intestial Enterobacteriaceae. The interesting properties of these compounds encourage us to synthesis some new of these compounds by a simple route, starting from (Chlorocarbonyl) phenyl ketene.     

Synthesis of naringin‐based polymer brushes via seATRP

The flavonoid‐based macromolecule initiator was prepared for the first time by the transesterification reaction of naringin with 2‐bromoisobutyryl bromide. In accordance with the “grafting from” methodology, a naringin‐based copolymer brush with a polar naringenine‐7‐rhamnosidoglucoside core and an amphiphilic poly(methyl methacrylate)‐block‐poly(N‐isopropylacrylamide) (PMMA‐b‐PNIPAM) side chains was synthesized for the first time via a simplified electrochemically mediated ATRP (seATRP), utilizing only 40 ppm of catalytic complex. The rate of the polymerizations was controlled by applying optimal potential or current values during preparative electrolysis to prevent the possibility of intermolecular coupling of the growing polymer brushes. Naturally derived polymer brushes showed narrow molecular weight distributions (Đ = 1.06−1.08). ¹H NMR spectral results confirm the formation of citrus‐based polymer brushes. These new naringin‐based polymer materials may find biomedical applications as thermo‐sensitive drug delivery systems, membranes, and biologically active thin films in tissue engineering.     

Synthesis of 2-Benzylthio-5-phenyl-3,4-disubstituted Thiophenes by Intramolecular Condensation of α-Oxo Ketene Dibenzyl~thioacetals

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ａｓａｋｉｎｄｏｆｖｅｒｓａｔｉｌｅｉｎｔｅｒｍｅｄｉａｔｅｓ ,α ｏｘｏｋｅｔｅｎｅｄｉｔｈｉｏａｃｅｔａｌｓ 1(Ｆｉｇ .1)ａｒｅｉｍｐｏｒｔａｎｔｉｎｏｒｇａｎｉｃｓｙｎｔｈｅ ｓｉｓ1ａｎｄｍｏｓｔｗｏｒｋｓａｒｅｆｏｃｕｓｅｄｏｎｔｈｅα ｏｘｏｋｅｔｅｎｅｄｉｍｅｔｈｙｌｔｈｉｏａｃｅｔａｌｓ .2 Ｉｎｏｕｒｓｔｕｄｉｅｓ ,ｉｔｉｓｆｏｕｎｄｔｈａｔｓｏｍｅｒｅａｃｔｉｏｎｓｕｐｏｎｔｈｅｓｅｋｉｎｄｏｆｉｎｔｅｒｍｅｄｉａｔｅｓａｒｅｍｏｄｕｌａｔｅｄｂｙｔｈｅ…     

Synthesis of silicon‐based polymer films by excimer laser‐induced photo‐reaction of phenylsilane and methylphenylsilane

The synthesis of silicon‐based polymer films was studied by excimer laser (248 nm)‐induced photo‐reaction of phenylsilane and methyl‐phenylsilane at reduced pressure. IR and UV–VIS results showed that the films were composed of Si–C network structures with phenyl rings. Copyright © 2000 John Wiley & Sons, Ltd.     

Control of microstructure and gradient property of polymer network by photopolymerizable silicone‐containing nanogel

This article reports a new type of silicone‐containing nanogel. The nanogel was dispersed in triethylene glycol dimethacrylate (TEGDMA) in increments between 10 and 40 wt % with a series of properties evaluated before and after polymerization. The nanogel raised monomer viscosity but did not significantly affect reaction kinetics or final conversion attained during photopolymerization. Polymerization stress was reduced progressively with the addition of nanogel with a significant delay in the onset of stress observed compared with the control. The self‐floating ability of the nanogel was demonstrated by elemental analysis and X‐ray photoelectron spectroscopy. As a result, the nanogel spontaneously formed a concentration gradient in the monomer prior to photopolymerization, leading to a gradient change of properties of the polymer. The research on surface morphology and elemental composition of PTEGDMA indicated the enrichment of the nanogel on the polymer surface, which resulted in enhanced hydrophobic character along with altered surface microstructure. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2830–2840     

Asymmetric hydrogenation of ketones catalyzed by silica‐supported chitosan‐iron‐nickel complex

A new silica‐supported biopolymer‐metal complex, silica‐supported chitosan‐iron‐nickel complex was prepared by a very simple method. This complex catalyst can be used as a catalyst in the asymmetric hydrogenation of propiophenone to (R)‐(+)‐1‐phenyl‐1‐propanol and acetophenone to (R)‐(+)‐1‐phenyl ethanol in 91.7 and 77.7% optical yields, respectively, at 110°C and under 70 kg/cm² pressure. The catalyst could be reused several times without any remarkable change in the catalytic activity. Copyright © 2004 John Wiley & Sons, Ltd.     

A two‐dimensional copper(II) coordination polymer based on 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid

Single‐crystal X‐ray diffraction analysis of poly[bis(μ₂‐5‐carboxy‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ³N³,O⁴:O⁵)copper(II)], [Cu(C₈H₉N₂O₄)₂)]_n, indicates that one carboxylic acid group of the 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PDI) ligand is deprotonated. The resulting H₂PDI⁻ anion, acting as a bridge, connects the Cu^II cations to form a two‐dimensional (4,4)‐connected layer. Adjacent layers are further linked through interlayer hydrogen‐bond interactions, resulting in a three‐dimensional supramolecular structure.     

Synthesis of Optically Active 1‐(1‐Phenylethyl)‐1H‐imidazoles Derived from 1‐Phenylethylamine

The three‐component reaction of (R)‐ or (S)‐1‐phenylethylamine ( 6 ), formaldehyde, and an α‐(hydroxyimino) ketone 5 , i.e., 3‐(hydroxyimino)butan‐2‐one ( 5a ) or 2‐(hydroxyimino)‐1,2‐diphenylethanone ( 5b ), yields the corresponding enantiomerically pure 1‐(1‐phenylethyl)‐1H‐imidazole 3‐oxide 7 in high yield (Schemes 2 and 3). The reactions are carried out either in MeOH or in AcOH. Smooth transformations of the N‐oxides into optically active 1‐(1‐phenylethyl)‐1H‐imidazoles 10 and 2,3‐dihydro‐1‐(1‐phenylethyl)‐1H‐imidazole‐2‐thiones 11 are achieved by treatment of 7 with Raney‐Ni and 2,2,4,4‐tetramethyl‐3‐thioxocyclobutanone ( 12 ), respectively (Scheme 4).     

Synthesis and structure‐activity relationship of several aromatic ketone‐based two‐photon initiators

Several novel aromatic ketone‐based two‐photon initiators containing triple bonds and dialkylamino groups were synthesized and the structure‐activity relationships were evaluated. Branched alkyl chains were used at the terminal donor groups to improve the solubility in the multifunctional monomers. Because of the long conjugation length and good coplanarity, the evaluated initiators showed large two‐photon cross section values, while their fluorescence lifetimes and quantum yields strongly depend on the solvent polarity. All novel initiators exhibited high activity in terms of two‐photon‐induced microfabrication. This is especially true for fluorenone‐based derivatives, which displayed much broader processing windows than well‐known highly active initiators from the literature and commercially available initiators. While the new photoinitiators gave high reactivity in two‐photon‐induced photopolymerization at concentration as low as 0.1% wt, these compounds are surprisingly stable under one photon condition and nearly no photo initiation activity was found in classical photo DSC experiment. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Interpenetrating polymer network hydrogels based on silicone and poly(2‐methacryloyloxyethyl phosphorylcholine)

In the present work, sequential interpenetrating polymer networks (IPNs) based on silicone and poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC) were developed with improved protein resistance. The structure and morphology of the IPNs were characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results showed that the IPNs exhibited heterogeneous morphology. The bulk properties such as water content, ion permeability, and mechanical strength of the IPNs were determined by gravimetric method, ionoflux measurement technique, and tensile tester, respectively. The surface characteristics of the IPNs were investigated by X‐ray photoelectron spectroscopy (XPS) and contact angle measurements. XPS analysis suggested that PMPC was present on the surface as well as in the bulk material. The IPNs possessed more hydrophilic surface than pristine silicone revealed by contact angle measurements. Bovine serum albumin (BSA) was used as a model protein to evaluate protein resistance by a bicinchoninic acid assay method. The result revealed that the protein adsorption on the IPNs was significantly reduced compared to pristine silicone. These results suggest that the IPNs based on silicone and PMPC may be developed as novel ophthalmic biomaterials. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis of well‐defined hairy polymer microspheres by precipitation polymerization and surface‐initiated atom transfer radical polymerization

A variety of polymer microspheres were successfully synthesized by the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of monomers by using monodisperse polymer microsphere having benzyl halide moiety as a multifunctional polymeric initiator. First, a series of monodisperse polymer microsphere having benzyl chloride with variable monomer ratio (P(St‐DVB‐VBC)) were synthesized by the precipitation polymerization of styrene (St), divinylbenzene (DVB), and 4‐vinylbenzyl chloride (VBC). Next, hairy polymer microspheres were synthesized by the surface‐initiated ATRP of various monomers with P(St‐DVB‐VBC) microsphere as a multifunctional polymeric initiator. The hair length determined by the SEC analysis of free polymer was increased with the increase of M/I. These hairy polymer microspheres were characterized by SEM, FT‐IR, and Cl content measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1296–1304     

Synthesis of main chain polymeric benzophenone photoinitiator via thiol‐ene click chemistry and Its use in free radical polymerization

Main chain polymeric benzophenone photoinitiator (PBP) was synthesized by using “Thiol‐ene Click Chemistry” and characterized with ¹H NMR, FTIR, UV, and phosphorescence spectroscopies. PBP as a polymeric photoinitiator presented excellent absorption properties (ε₂₉₄ = 28,300 mol^?1L^?1cm^?1) compared to the molecular initiator BP (ε₂₅₂ = 16,600 mol^?1L^?1cm^?1). The triplet energy of PBP was obtained from the phosphorescence measurement in 2‐methyl tetrahydrofurane at 77 K as 298.3 kJ/mol and according to phosphorescence lifetime, the lowest triplet state of PBP has an n‐π* nature. Triplet–triplet absorption spectrum of PBP at 550 nm following laser excitation (355 nm) were recorded and triplet lifetime of PBP was found as 250 ns. The photoinitiation efficiency of PBP was determined for the polymerization of Hexanedioldiacrylate (HDDA) with PBP and BP in the presence of a coinitiator namely, N‐methyldiethanolamine (MDEA) by Photo‐DSC. The initiation efficiency of PBP for polymerization of HDDA is much higher than for the formulation consisting of BP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

An Efficient One‐pot Synthesis of Pyrazolone Derivatives Promoted by Acidic Ionic Liquid

A new class of pyrazolone derivatives has been isolated in good to excellent yields from the 2:1 condensation reaction between 3‐methyl‐1‐phenyl‐5‐pyrazolone and arylaldehydes in the presence of ionic liquid [HMIM]HSO₄. The compounds were characterised by their IR, NMR spectra, MS and elemental analyses. The important features of the methodology are a wide application range of substrates, higher yields and shorter reaction time.     

Synthesis of organic sulfobetaine‐based polymer gel electrolyte for dye‐sensitized solar cell application

We have synthesized eco‐friendly, economic, and equally efficient polysulfobetaine‐based gel electrolyte to the alternative of liquid electrolyte in the fabrication of dye‐sensitized solar cells (DSSCs) for the first time. This nitrogen‐rich and highly conductive polysulfobetaine was synthesized by an easy and facile method without the use of any catalyst and explored for its DSSC application. The synthesized polymer gel electrolyte exhibited good ionic conductivity about 6.8 × 10^?3 Scm^?1 at ambient temperatures. DSSCs were fabricated based on this polysulfobetaine gel electrolyte and studied for their performance based on photovoltaic parameters. The DSSC photovoltaic results were appreciable and are Voc = 0.82 V, Jsc = 11.49 mA/cm², FF = 66%, and PCE = 6.26% at 1 sun intensity. These values are slightly lower than conventional liquid electrolyte‐based DSSC shown as Voc = 0.78 V, Jsc = 12.90 mA/cm², FF = 69%, and PCE = 7.07%, both at 100 mWcm^?2. Conductivity and photovoltaic parameters of the device reveals that as prepared polysulfobetaine‐based polymer gel electrolyte may be useful in the fabrication of DSSC and other electrochemical devices. Copyright © 2017 John Wiley & Sons, Ltd.     

Nanostructure and properties of polysiloxane‐layered silicate nanocomposites

The relationship between nanostructure and properties in polysiloxane layered silicate nanocomposites is presented. Solvent uptake (swelling) in dispersed nanocomposites was dramatically decreased as compared to conventional composites, though intercalated nanocomposites and immiscible hybrids exhibited more conventional behavior. The swelling behavior is correlated to the amount of bound polymer (bound rubber) in the nanocomposites. Thermal analysis of the bound polymer chains showed an increase and broadening of the glass‐transition temperature and loss of the crystallization transition. Both modulus and solvent uptake could be related to the amount of bound polymer formed in the system. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1595–1604, 2000