Vibrational spectroscopic investigation of light‐induced polymerization process of epoxy resin,polytetrahydrofuran and spirobislactone

The light‐induced polymerization process of bisphenol F diglycidyl ether (BFDGE), 5,5′‐dicarboxylic‐7,7′‐dioxo‐2,2′‐spirodi(benzotetrahydrofuran) (DCSBL) and polytetrahydrofuran (pTHF‐250) was studied. 4‐[(2‐Hydroxytetradecyl)oxy]phenyl‐phenyliodoniumhexafluoroantimonate, camphorquinone and ethyl 4‐dimethylaminobenzoate were used as a photoinitiator system. The polymerization process was induced by light and monitored using Fourier transform infrared spectroscopy. A novel combination‐initiation polymerization process was proposed: first, cationic copolymerization of BFDGE and pTHF‐250 was initiated by the photoinitiator system and heat was released by this polymerization; then, copolymerization of BFDGE and DCSBL was induced by that heat while pTHF‐250 served as an anionic initiator. Copyright © 2007 Society of Chemical Industry     

Synthesis and photopolymerization characterization of a novel difunctional photoinitiator

A novel difunctional photoinitiator HBP‐TDI‐HBP based on 4‐hydroxybenzophenone (HBP) and toluene‐2,4‐diisocyanate (TDI) was synthesized and characterized by ¹H NMR and UV–Vis absorption spectroscopy. The kinetics of photopolymerization was studied by real‐time infrared spectroscopy. It showed that HBP‐TDI‐HBP was a more effective photoinitiator than benzophenone. When this photointiator and amine were used to efficiently initiate polymerization of acrylates and methacrylates, both rate of polymerization and final conversion increased with increase of HBP‐TDI‐HBP concentration, light intensity, and amine concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Benzophenone-di-1,3-dioxane as a novel initiator for free radical photopolymerization

Benzophenone-di-1,3-dioxane (BP-DDO), a novel photoinitiator for free radical polymerization, was synthesized and characterized. The photopolymerization kinetics of BP-DDO was studied by real-time infrared spectroscopy (FT-IR). When this photointiator was used to efficiently initiate polymerization of acrylates and methacrylates, there was an optimum cure rate with the increase in BP-DDO concentration. Both the polymerization rate and final conversion increased with the increase in light intensity. The kinetics study of photopolymerization of TMPTA showed that BP-DDO was a more effective photoinitiator than benzophenone and benzophenone/ethyl-4-dimethylaminobenzoate (EDAB).     

Synthesis and photopolymerization kinetics of polymeric one‐component type II photoinitiator containing benzophenone moiety and tertiary amine

A polymeric one‐component type II photoinitiator (PDABPP) based on 4,4′‐dihydroxybenzophenone (DHBP), acryloyl chloride, and piperazine was synthesized, and its structure was confirmed by GPC and ¹H NMR. The photopolymerization kinetics of the photoinitiator was studied by real‐time infrared spectroscopy. It indicated that PDABPP was a more effective photoinitiator than that of benzophenone (BP)/triethylamine (TEA). The rate of polymerization and final conversion increased, and the induction period shortened with increase of PDABPP concentration, light intensity, and amine concentration. The kinetics of photopolymerization for tripropylene glycol diacrylate (TPGDA) incorporating PDABPP in the presence of different tertiary amines as the initiating system indicated that the PDABPP/TEA combination exhibited the highest polymerization rates among the PDABPP/amines combinations. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Novel sulfur—containing benzophenone derivative as radical photoinitiator for photopolymerization

A novel, highly efficient, polymerizable sulfur‐containing photoinitiator for free radical polymerization, benzophenone thio‐acetic acid (BP‐S‐CH₂‐COOH) was synthesized, characterized, and compared to photoinitiator parameters of the benzophenone (BP) and benzophenone/(phenylthio)acetic acid couple. The photoinitiator possesses a greatly redshifted UV maximal absorption in comparison to BP. Laser flash photolysis studies suggest that photoinitiator radicals are generated by photocleavage of C? S bond. Photopolymerization of 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol triacrylate (TMPTA) demonstrated that one‐component system BP? S? CH₂? COOH is more efficient for polymerization than two‐component system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

可聚合型光引发剂4-丙烯酰氧基二苯甲酮的光聚合性能研究

以实时红外光谱（RT-IR）法研究了合成的4-丙烯酰氧基二苯甲酮（4-ABP）的光聚合动力学性质，考察了不同单体、不同引发剂和助引发剂浓度、不同光强对聚合性能的影响．以萃取法对比研究了4-ABP和二苯甲酮（BP）在固化膜中的的残留量．结果表明，4-ABP是一种非常有效的光引发剂．随着引发剂浓度和光强的增大，单体转化率、最大反应速率都增大，诱导期缩短．萃取实验表明4-ABP在固化膜中的残留量远低于BP．     

Synthesis and characterization of 4,4′-diacryloyloxybenzophenone

A copolymerizable type II photoinitiator 4,4′-diacryloyloxybenzophenone (DABP) based on 4,4′-dihydroxybenzophenone (DHBP) and acryloyl chloride was synthesized, and its structure was confirmed by ¹H NMR and real-time infrared spectroscopy. UV–vis absorption spectroscopy of DABP exhibited red-shifted maximal absorption as compared with benzophenone (BP). The kinetics of photopolymerization was studied by real-time infrared spectroscopy. It showed that DABP was a more effective photoinitiator than benzophenone. When this photointiator and amine was used to efficiently initiate polymerization of acrylates and methacrylates, both rate of polymerization and final conversion increased and the induction period was shortened with increase of amine concentration, DABP concentration and light intensity.     

Photopolymerization of 1‐adamantyl acrylate pohotoinitiated by free radical photoinitiators

1‐Adamantyl acrylate was synthesized by reacting of 1‐adamantanol with acryloyl chloride in the presence of tertiary amine. The structure of monomer was characterized by FTIR and ¹H NMR spectroscopy. The influence of photoinitiator and monomer types on the photopolymerization kinetics of this monomer was investigated by real‐time infrared spectroscopy (RTIR). In the UV curing system, the introduction of 1‐adamantyl acrylate could significantly reduce the polymerization shrinkage. Thermogravimetric analysis of 1‐adamantyl acrylate indicated that 1‐adamantyl acrylate polymer has higher thermal stability than that of general commercial products. The results indicated that the synthesized monomer has good curing performance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and photopolymerization kinetics of oxime ester photoinitiators

Oxime Ester (OXE) Photoinitiators were synthesized and characterized by HPLC, FTIR, UV–Vis spectra, and ¹H‐NMR. The UV–Vis spectra of these photoinitiators were similar to Benzophenone (BP) but showed large red‐shifted maximum absorption. OXE were not only soluble in many solvents and (meth) acrylate monomers but also could be dispersed easily in propylene glycol monomethyl ether acetate (PGMEA). The kinetics of polymerization of monomer using OXE as photoinitiator was studied by Real‐time infrared (RTIR) spectra. It showed that OXE were an efficient photoinitiator. The concentration of OXE, functionality of monomer, and light intensity had effect on the photopolymerization kinetics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of triazine‐based dendrimers and their application in metal ion adsorption

This article described the synthesis of triazine‐based dendrimers with poly(ethylene glycol) core by convergent method. Compound 1 was prepared by coupling of amino group of diethanolamine with cyanuric chloride in dry THF (tetrahydrofuran). Reaction of compound 1 with p‐aminobenzylamine resulted in compound 2 . Compound 4 was synthesized using coupling reaction of amino group of compound 2 with cyanuric chloride, then coupling of amine groups of p‐aminobenzylamine with compound 3 in the hybrid solvents. The final dendrimer (den‐OH) were synthesized using reaction of dendron 4 with compound 5. Ethylene diaminetetraacetic acid modified final dendrimer were successfully prepared via coupling ethylene diaminetetraacetic acid dianhydride and den‐OH. The growth of dendrons and their structures were investigated by using usual spectroscopy methods and elemental analysis. The chelating behavior and sorption capacities of triazine dendrimers were determined in relation to pH dependency for some metal ions such as Cu⁺², Ni⁺², and Zn⁺² using atomic absorption methods. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Photopolymerization characteristics of bisbenzo[1,3]dioxol‐5‐ylmethanone as an initiator

Bisbenzo[1,3]dioxol‐5‐ylmethanone (BBDOM), a type of hydrogen‐abstraction photoinitiator, exhibited redshifted maximal absorption in comparison with benzophenone (BP) according to ultraviolet–visible absorption spectroscopy. The kinetics of photopolymerization of the photoinitiator in different systems was studied with real‐time infrared spectroscopy. The concentration of BBDOM, the components of the initiator, and the functionality of the monomer had great effects on the kinetics of photopolymerization. The results show that BBDOM is a more effective photoinitiator than BP. BBDOM consists of cyclic acetals that are widely distributed in nature, and with BBDOM, the use of large numbers of amines can be avoided in the system without the requirement of an additional hydrogen donor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

1,3-dioxane methylcoumarin as a novel photoinitiator for free radical polymerization

1,3-Dioxane methylcoumarin (DOMC), a novel photoinitiator (PI) for free radical polymerization, was synthesized and characterized. UV–vis absorption spectroscopy was used to investigate its photochemical behavior during the photophysical process. The photopolymerization kinetics of DOMC was studied by real-time infrared spectroscopy (FTIR). There was an optimum curing rate with the increase in DOMC concentration. Both the polymerization rate and final conversion increased with the increase in light intensity. DOMC was the most efficient PI for tripropylene glycol diacrylate (TPGDA) in different acrylate monomers. The kinetics study of TPGDA photopolymerization showed that DOMC was a more effective PI than benzophenone/ethyl-4-dimethylaminobenzoate. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Optical anisotropy of chalcone-based epoxy compound under irradiation of linearly polarized UV light

Photocrosslinkable chalcone-epoxy compound comprising 1,3-bis-(4-hydroxy-phenyl)-propenone was synthesized for studying the optically induced anisotropy of the thin films. Chalcone group was introduced into the main chain unit of the epoxy oligomer. We observed a photodimerization behavior and an optical anisotropy of this material by irradiation of linearly polarized UV light (LPL). With a trace amount of cationic photoinitiator, polymerization of epoxy groups was also conducted at the similar wavelength range used for photodimerization. Optical anisotropy of the thin film was also investigated by using polarized FT-IR and UV absorption spectroscopy either with or without cationic photoinitiator. Two kinds of photochemical reaction were employed to enhance the anisotropy using the chalcone-epoxy compound.     

Photopolymerization kinetics of cycloaliphatic epoxide–acrylate hybrid monomer

An epoxide–acrylate hybrid monomer was synthesized by the controlled reaction of a cycloaliphatic epoxide and acrylic acid. The photopolymerization kinetics was investigated using a real‐time infrared spectroscopy technique. The influences of photoinitiator concentration, free radical initiator and polymerization atmosphere on the polymerization were studied. The hybrid monomer showed unique photopolymerization kinetics in the photopolymerization process and the final conversions of epoxy groups and acrylate double bonds were improved synchronously. Dynamic mechanical analysis results demonstrated that the hybrid monomer cured film formed a more uniform polymer network than the blend of epoxy acrylate and epoxide. Copyright © 2007 Society of Chemical Industry     

A glance at violet LED sensitive photoinitiators based on the spiroxanthene scaffold

A novel photoinitiator based on a spiroxanthene scaffold in the presence of an iodonium salt is proposed for the cationic ring‐opening polymerization of a diepoxide, as well as for the free‐radical polymerization of an acrylate upon violet LED exposure (385 and 405 nm). Good‐to‐excellent rates of polymerization and final conversions are obtained. These systems are characterized by a higher reactivity compared with that of anthracene/iodonium salt used as reference for cationic near UV polymerization. The addition of a poly(ionic liquid) improves the cationic polymerization profiles. The photochemical mechanisms are studied by steady‐state photolysis, fluorescence, and electron spin resonance spin‐trapping techniques. Molecular orbital calculations give an insight into the light absorption properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43213.     

A study of the photopolymerization kinetics of methyl methacrylate using novel benzophenone initiators

A series of novel bifunctional photoinitiators with benzophenone moieties were synthesized. Characterization of these molecules was performed using IR, UV, ¹H NMR, ¹³C NMR and mass spectroscopy. Photopolymerization of methyl methacrylate, a model acrylate‐type monomer, was carried out with the bifunctional benzophenone molecules functioning as the photoinitiator and triethylamine as the co‐initiator. The progress of the polymerization was followed by dilatometry. The resulting plots of monomer conversion with time were used to evaluate the initial rates of polymerization. The relative enhancement/lowering of the rates of polymerization, with respect to benzophenone as the model photoinitiator, are interpreted in terms of the structure, and the photophysics of the initiator evaluated by nanosecond laser flash photolysis. © 2001 Society of Chemical Industry     

Ultraviolet‐curing behavior of an epoxy acrylate resin system

Ultraviolet (UV)‐curing behavior of an epoxy acrylate resin system comprising an epoxy acrylate oligomer, a reactive diluent, and a photoinitiator was investigated by Fourier transform infrared (FTIR) spectroscopy. The conversion changes of the resin system containing 20 phr of 1,6‐hexanediol diacrylate as a reactive diluent and 2‐hydroxy‐2‐methyl‐1‐phenyl‐propan‐1‐one as a photoinitiator were measured under different UV‐curing conditions. The fractional conversion was calculated from the area of the absorption peak for the vinyl group vibration occurring at 810 cm^?1. The effects of photoinitiator concentration, total UV dosage, one‐step or stepwise UV irradiation, UV intensity, atmosphere, and temperature on the curing behavior of the resin system were investigated. The conversion of the resin system increased rapidly at the initial stage of the UV‐curing process but increased very slowly after that. The final conversion of the resin system was mainly affected by total UV dosage. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1180–1185, 2005     

The effect of photoinitiator concentration and structures of RAFT macroinitiators on the memory effect of polymer dispersed liquid crystals

The article aimed to decrease the memory effect of polymer dispersed liquid crystals (PDLCs) films, reversible additional‐fragmental chain transfer (RAFT) polymerization was used to synthesize RAFT‐polystyrene (RAFT‐PS), which was a kind of RAFT macroinitiators and used to prepare PDLCs via photo polymerization induced phase separation (PIPS). Different RAFT agents were used to synthesize RAFT‐PS. The effect of photoinitiator concentration on the memory effect of these PDLCs was investigated, and the effect of structures of RAFT macroinitiators on the memory effect of the PDLCs was also discussed. The results showed that PDLC films with higher photoinitiator concentration and polymer matrix which had two rigid chains in two ends showed lower memory effect, which could be reduced from 10.9% to 2.5% in this experiment. POLYM. ENG. SCI., 55:8–13, 2015. © 2014 Society of Plastics Engineers     

Preparation and antidehydration of interpenetrating polymer network hydrogels based on 2‐hydroxyethyl methacrylate and N‐vinyl‐2‐pyrrolidone

This work reports the preparation of 2‐hydroxyethyl methacrylate (HEMA)/N‐vinyl‐2‐pyrrolidone (NVP) interpenetrating polymer network (IPN) hydrogels by UV‐initiated polymerization in the presence of free radical photoinitiator Darocur 1173 and cationic photoinitiator 4,4′‐dimethyl diphenyl iodonium hexafluorophosphate. The polymerization mechanism was investigated by the formation of gel network. The structure and morphology of the HEMA/NVP IPN hydrogels were characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results showed that the IPN gels exhibited homogeneous morphology. The dehydration rates of HEMA/NVP IPN hydrogels were examined by the gravimetric method. The results revealed that the hydrogels had a significant improvement of antidehydration ability in comparison with poly(2‐hydroxyethyl methacrylate)(PHEMA) hydrogel embedded physically with poly(N‐vinyl‐2‐pyrrolidone)(PVP). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

一种新型的复合型光引发剂的制备及其光聚合性质

利用4-羟基二苯甲酮（ HBP）,丙烯酰氯和吗啡啉为原料,合成了一种新型的复合型光引发剂（ BPMDO）,通过核磁共振氢谱和红外光谱来表征其结构。用实时红外光谱（ RT-IR）技术研究了光引发剂的浓度、不同单体对光聚合动力学的影响。结果表明, BPMDO是一种有效的光引发剂,随着引发剂浓度增大,单体转化率、引发速率增大,诱导期缩短。