Kinetic study on the UV‐induced photopolymerization of epoxy acrylate/TiO2 nanocomposites by FTIR spectroscopy

The kinetics of the photopolymerization of epoxy acrylate/TiO₂ nanocomposites, with 2′2‐dimethoxy‐1,2‐diphenylethan‐1‐one (Irgacure 651) or benzophenone/N‐methyl diethanolamine as photoinitiators, were studied by FTIR spectroscopy. It was found that nanocomposites had a decreasing photopolymerization rates in comparison with pure epoxy acrylate. The photopolymerization rate of the nanocomposite could also be influenced by initiator types, oxygen, film thickness, irradiation intensity, dispersing media of TiO₂ slurry, and so forth. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3281–3287, 2006     

Infrared process monitoring of conjugated linoleic acid/styrene/butyl acrylate bulk and emulsion terpolymerization

Free radical bulk and emulsion co‐ and terpolymerizations of conjugated linoleic acid (CLA) with styrene (Sty) and butyl acrylate (BA) were performed at 80 °C. The polymerizations were monitored using an attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopic probe. Bulk polymerizations were monitored off‐line while emulsion polymerizations were monitored in‐line. Absorbance peaks related to the monomers and polymer were tracked to provide conversion and polymer composition data using a multivariate calibration method. Off‐line measurements using gravimetry and ¹H‐NMR spectroscopy were compared to the ATR‐FTIR data and no significant differences were detected between the measurement methods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43574.     

In situ study of photopolymerization by fourier transform infrared spectroscopy

The Fourier transform infrared (FTIR) in situ method was developed for the investigation of photopolymerization. Ultraviolet (UV) cure of a mixture of a cycloaliphatic epoxide, a 2-ethylhexyl acrylate, and photoinitiators, which forms simultaneous interpenetrating polymer network (IPN), was monitored while the sample was irradiated with UV light. Triphenylsulfonium salt and benzoin ether were used as photoinitiators. For the sake of comparison, similar experiments were performed for the epoxide with the triphenylsulfonium salt photoinitiator and the acrylate with the benzoin ether photoinitiator. The epoxy photopolymerization was monitored using an epoxy CH stretching band at 3005 cm^?1 and a ring vibration band at 790 cm^?1. The acrylic photopolymerization was monitored using a C?C stretching band at 1637 cm^?1. The epoxy conversion was less than 60% when the acrylic polymerization was completed in the IPN.     

Synthesis, photopolymerization kinetics, and thermal properties of UV-curable waterborne hyperbranched polyurethane acrylate dispersions

A series of UV-curable waterborne hyperbranched polyurethane acrylate dispersions (WHBPUADs) were prepared via a three-step procedure based on isophorone diisocyanate (IPDI), hyperbranched polyester (HBP), maleic anhydride (MA), and hydroxy-ethyl acrylate (HEA). The structure of WHBPUADs was characterized by Fourier transform infrared spectroscopy (FTIR) and ¹H nuclear magnetic resonance spectroscopy (¹H NMR). FTIR was also applied to research the effect of double bond concentration on the kinetics of photopolymerization. The heat resistance of the cured films was characterized by thermogravimetric analysis (TGA), and their mechanical properties were also measured. The results showed that the double bond conversion (τ) and photopolymerization rate (R _p) were affected by the concentration of double bond and viscosity of WHBPUADs. The UV-curable systems with higher double bond concentration and lower viscosity led to higher τ and R _p. The maximum τ and R _p reached 93% and 71 mmol g⁻¹ s⁻¹, respectively. The WHBPUADs films possessed better heat resistance and mechanical properties, and with the increase of crosslink density, the heat resistance and hardnesses were further improved.     

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 characterization of styrene–acrylic ester copolymers

Homopolymers and copolymers of styrene and different acrylic esters (i.e., acrylates) were synthesized by the free‐radical solution polymerization technique. Feed ratios of the monomers styrene and cyclohexyl acrylate/benzyl acrylate were 90 : 10, 75 : 25, 60 : 40, 50 : 50, 40 : 60 and 20 : 80 (v/v) in the synthesis of copolymers. All 6 homopolymerizations of acrylic ester synthesis were carried out in N,N(dimethyl formamide) except for the synthesis of poly(cyclohexyl acrylate) (PCA), where the medium was 1,4‐dioxane. Benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN) were used as initiators. The polymers synthesized were characterized by FTIR, ¹H‐NMR, ¹³C‐NMR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and viscosity measurements. The reactivity ratios were determined by the Fineman–Ross method using ¹H‐NMR spectroscopic data. The reactivity ratios (r) for the copolymerization of styrene (r_S) with cyclohexyl acrylate (r_CA) were found to be r_S = 0.930 and r_CA = 0.771, while for the copolymerization of styrene with benzyl acrylate, the ratios were found to be r_S = 0.755 and r_BA = 0.104, respectively. The activation energies of decomposition (E_a) and glass‐transition temperature (T_g) for various homo‐ and copolymers were evaluated using TGA and DSC analysis. The activation parameters of the viscous flow, voluminosity (V_E) and shape factor (ν) were also computed for all systems using viscosity data. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1513–1524, 2001     

Photo‐differential scanning calorimetry study on photopolymerization of nanosized titanium dioxide/polyacrylate hybrid materials

Nanosized titania–polyacrylate hybrid films were prepared by controlled hydrolysis of titanium tetrabutoxide (TTB) in Span 85/Tween 80 reverse micelles as well as rapid entrapment of nanosized particles by subsequent photopolymerization. This work focused on the characterization of the photopolymerization of the transparent hybrid films via photocalorimetry. The polymerization kinetics of several mixtures of mono‐ and di‐functional acrylate monomers were compared to examine the effect of average functionality. Further, Effects of [H₂O]/[surfactant] molar value and TTB concentration on photopolymerization kinetics were also studied. X‐ray photoelectron spectra and FTIR demonstrated the formation of TiO₂ in the hybrid films. Atomic Force Microscope (AFM) images showed the inorganic domains with mean sizes of 25 nm were uniformly dispersed in the polymeric networks. Copyright © 2006 Society of Chemical Industry     

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     

The photosensitive properties of polysiloxane acrylate resin containing tertiary amine groups

The photosensitive properties of a novel oligomer, di (N,N‐diacrylolyl)‐α, ω‐diaminopolysiloxane (ANS) with tertiary amine groups and acryloyl groups in its molecular structure were investigated using FTIR and gel yield method. It was noted that the ANS system showed a notable photosensitive property and its photosensitivity in air could be up to16.3 mJ/cm². The UV‐curing behavior of the ANS was studied by electron spin resonance (ESR). The results showed that amino‐alkyl radicals can be formed by excited BP abstracting hydrogen at a‐carbon bonded with nitrogen in the ANS molecule under UV irradiation, which can mitigate the oxygen inhibition in radical polymerization. It is proven that tertiary amine groups introduced into ANS could boost photosensitivity of the photopolymerization system. The oligomer ANS may find application in photopolymerization to improve the properties of UV‐curing coating materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of superabsorbent resin by ultraviolet photopolymerization

Synthesis of superabsorbent resin (SAR) was achieved by a new method, that of direct UV photopolymerization, and in particular the synthesis of a SAR of acrylic acid–potassium acrylate copolymer by UV photopolymerization was investigated. Influences of ratio (mol) of acrylate monomer to acrylic acid monomer, photoinitiators, crosslinking agents, and exposure time of UV light on the water‐absorbent properties were investigated. The results showed that the water absorbency (Q) of SAR based on Irgacure 1700 or Irgacure 1800 was 545–530 mL/g, but under the same conditions Q was 450 mL/g for the SAR based on Irgacure 651. N,N′‐Methylene bisacrylamide, hydroethyl acrylate, and glycerol were used as crosslinking agents, of which N,N′‐methylene bisacrylamide was the most effective. It crosslinked the molecular chains through attending the copolymerization with acrylic acid (AA) and potassium acrylate. When the exposure time was 5 min, the value of Q was 1368 mL/g (the content of N,N′‐methylene bisacrylamide was 100 ppm). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1618–1624, 2004     

Poly(vinyl acetate)/polyacrylate semi‐interpenetrating polymer networks,part 1: Synthesis and polymerization kinetics

Bulk photopolymerization was used to synthesize a series of semi‐interpenetrating polymer network (s‐IPN) based on linear poly(vinyl acetate) and crosslinked N‐butyl acrylate/1,6‐hexandiol diacrylate (HDDA) copolymer. Different formulations were used by varying the monoacrylate/diacrylate molar ratio and the linear polymer concentration. The polymerization kinetics was studied as a function of the s‐IPN composition by FTIR spectroscopy. It was observed that the reaction rate increases by increasing the linear polymer amount. This effect is much more pronounced in the reaction mixtures with a higher diacrylate concentration, playing a key role the restricted mobility of the macroradicals involved in the bimolecular termination. The maximum conversion increases regularly with linear polymer concentration in the blend and resulted to be very high, ranging from 95 to 98%. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Superabsorbent resin of acrylic acid/ammonium acrylate copolymers synthesized by ultraviolet photopolymerization

A new method of synthesizing a superabsorbent resin (SAR) from an acrylic acid/ammonium acrylate copolymer by direct UV photopolymerization was studied. The effects of the degree of neutralization of acrylic acid, the photoinitiators, the crosslinking agents, and the UV‐light exposure time on the water absorbency (Q) were investigated. The results showed that Q of an SAR based on Irgacure 1700 or Irgacure 1800 and Irgacure 651 was high, reaching about 1200 mL/g, but under the same conditions, Q was low for an SAR based on other photoinitiators. The UV absorption spectrum proved that the photoinitiators matched the UV light source. Among the crosslinking agents, N,N′‐methylene bisacrylamide was more efficient than the others at a small concentration and a high value of Q. ¹³C‐NMR spectrometry was used to identify the mechanism of the crosslinking reaction through the esterification of hydroxyethyl acrylate (HEA) and 2‐hydroxypropyl acrylate with carboxylic acid group in acrylic acid/ammonium acrylate copolymerization, but the efficiency of the crosslinking reaction by esterification was lower than that of the copolymerization of vinyl groups in the crosslinking agent. Q of the acrylic acid/ammonium acrylate copolymer for the SAR reached 1255 mL/g under certain conditions (degree of neutralization of acrylic acid = 75%, Irgacure 651 concentration = 0.2 wt %, [HEA] = 0.2 wt %, exposure time = 10 min). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 546–555, 2005     

Superabsorbent hydrogel of acrylic acid/potassium acrylate copolymers by ultraviolet photopolymerization: Synthesis and properties

Synthesis of superabsorbent hydrogel (SAHG) of acrylic acid‐potassium acrylate copolymer by direct Ultraviolet (UV) photopolymerization is a new method. The effects of degree of neutralization of acrylic acid (AA), photoinitiators, crosslinking agents, and exposure time of UV light on water absorbent properties were investigated. The results showed that the water absorbency (Q) and the salt solution (NaCl, 0.9%) absorbency (Qs) of SAHG, based on Irgacure 651, are high, reaching about 1400 and 130 mL/g, respectively. UV absorption spectrum proved that peak of UV absorption of Irgacure 651 matched the UV light source we used. Among the crosslinking agents, N,N′‐methylene bisacrylamide is more efficient than others, because of its very small content and high Q. ¹³C NMR spectrometry was used to identify the mechanism of crosslinking reaction through esterification of hydroxyethyl acrylate (HEA) and 2‐hydroxypropyl acrylate (HPA) with carboxylic acid group in acrylic acid‐ammonium acrylate copolymerization, but efficiency of crosslinking reaction by esterification was lower than that of copolymerization of vinyl group in crosslinking agent. The Q of acrylic acid‐potassium acrylate copolymer of SAHG reaches 1592 mL/g under the following conditions: degree of neutralization of acrylic acid is 80%, content of Irgacure 651 is 0.25 wt %, content of HEA is 0.2 wt %, and exposure time is 10 min. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1181–1187, 2006     

Preparation of multifunctional thiol‐ and acrylate‐terminated polyurethane: A comparative study on their properties in UV curable coatings

The multifunctional thiol‐ and acrylate‐terminated polyurethane (PU) has been successfully prepared for using as the main resin in the UV curable coatings. The structure and molecule weight of prepared PUs were analyzed by fourier transformed infrared spectroscopy (FTIR) and gel permeation chromatography, respectively. The results showed that the different terminal multifunctional groups have been grafted onto the PU and their difference in molecule weight was significant. Used as the main resin in coatings, the curing kinetic and percentage conversion of the different UV curing coatings system were investigated by real‐time FTIR method, and the effects of terminal functional groups and photoinitiator on the final conversion percentage and conversion rate were also compared. It is observed that the thiol‐terminated PU had higher conversion speed and final conversion percentage due to the remarkable effect of mercapto groups on reducing oxygen inhibition during UV curing process. The shrinkage, viscosity, and adhesion of UV curable coatings with thiol‐ and acrylate‐terminated PUs were also investigated and compared, and the results indicated that the former exhibited lower shrinkage and higher adhesion performances than the latter, along with the lower viscosity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40740.     

Swelling behavior of poly(n‐butyl acrylate/1,6‐hexane‐diol‐di‐acrylate)/nematic liquid crystal E7 systems: Experimental measurements and modeling by factorial design method

The swelling process of poly(n‐butyl acrylate/1,6‐hexane‐diol‐di‐acrylate) [Poly(Abu/HDDA)] networks, immersed in a liquid crystalline (LC) solvent, was investigated in order to obtain improved swelling ratio values upon application of an original method using a central composite design. The polymer/LC systems under investigation were elaborated via a photopolymerization/crosslinking phase separation process induced by UV radiation of initial mixtures composed of mono‐ and bifunctional monomers, a photoinitiator, and the low‐molar‐weight nematic LC blend E7. The parameters which strongly impact the swelling behavior of Poly(Abu/HDDA)/E7 systems were identified as temperature and concentration of the bifunctional monomer in the initial photopolymerizable mixture, thus controlling the crosslinking density of the final polymer network. The existence of interactions and synergies between these two parameters were also examined. The quality of the model was verified by a good agreement between experimental results and predicted response. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45230.     

Synthesis and thiol–ene photopolymerization of (meth)allyl‐terminated polysulfides

Thiol‐terminated polysulfides (PS) are cured by mixing with an oxidant, resulting in limited shelf‐ and/or pot‐life, depending on whether formulated as a one‐ or two‐component system. Mixtures of thiol‐ and alkene‐terminated polysulfides offer the potential for an on‐demand curing process through thiol–ene photopolymerization. Thiol end groups of commercial polysulfides, PS‐1 (1000 g/mol) and PS‐2 (3000 g/mol), were converted to alkene by reaction with (meth)allyl bromide. Photopolymerizations were performed by irradiating films of equimolar thiol:ene mixtures at 320–500 nm (30 mW/cm²) in the presence of 5 wt % 2,2‐dimethoxy‐2‐phenyl‐acetophenone (DMPA). Reaction kinetics were measured using real‐time FTIR by monitoring absorbances at 3075 cm^?1 (alkene) or 2550 cm^?1 (thiol). In the absence of any reactive diluent, mixtures of thiol and alkene polysulfides failed to gel notwithstanding high reaction conversion (>90%). Partial or total replacement of the thiol polysulfide component with pentaerythritol tetrakis(3‐mercaptopropionate) (PETMP) yielded solid elastomeric films and ultimate reaction conversions of 80–96% after 5 min irradiation. Crosshatch adhesion measured on glass, aluminum, and steel was very poor (0B) for (meth)allyl PS‐1/PETMP and poor (2B) for (meth)allyl PS‐2/PETMP without adhesion promoters. (3‐Mercaptopropyl)trimethoxysilane (1 wt %) significantly improved adhesion of (meth)allyl PS‐2/PETMP on all substrates (4B) but yielded no improvement for (meth)allyl‐terminated PS‐1/PETMP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45523.     

Synthesis of urethane acrylate based electromagnetic interference shielding materials

In this work, a new method, consists of synthesis of urethane acrylate (UA) followed by in situ polymerization of pyrrole using cerium (IV) as an oxidant and UV‐curing of the composites, for preparing polypyrrole–UA (PPy–UA) composite films was described. It appeared that dielectric constants of the composites increased with increasing the PPy content and decreased with increasing the frequency from 10^?2 to 10⁷, indicating an interfacial Maxwell–Wagner contribution to the permittivity. An incorporation of a small amount of PPy (15% Py) to UA matrix increased their dielectric constants more than 4 × 10⁴ (41,259) at 10^?2 Hz. So, the incorporation of PPy was very effective for enhancing the dielectric properties of UA matrix. Furthermore, the significant enhancement in dielectric properties (loss tangent and dielectric constant) contributes to the improvement in electromagnetic interference shielding efficiency. Composite films were characterized using Fourier transform infrared attenuated total reflectance (FTIR‐ATR) spectrophotometer and ¹H‐NMR. It was seen that PPy is blended with the UA matrix at the molecular level through H‐bonding interactions. A linear relationship was also observed between the characteristic groups' absorbances of PPy (from FTIR‐ATR) and dielectric constant values (from dielectric spectrometer). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Novel benzoxazine resins as photoinitiator comprising benzophenone and coinitiator amine for photopolymerization

A novel kind of benzoxazine precursors made of 4‐dihydroxybenzophenone (DHBP), formaldehyde and N, N′‐diethylethylenediamine was developed. The striking feature of this class of precursors is that it can be acted as an effective photo initiator for polymerization of acrylate monomers. In addition, this kind of precursors could be directly dispersed in water and its aqueous solution exhibited very sharp response to temperature, with a well‐defined cloud point. The structure of this precursor has been confirmed by Proton Nuclear Magnetic Resonance Spectroscopy (¹H‐NMR) and Fourier Transform Infrared spectroscopy (FTIR) and its curing behaviors are investigated by Differential Scanning Calorimetry (DSC). The photopolymerization of acylate monomers, initiated by this precursor, was studied through photo‐DSC. The results show that this precursor is dramatically more efficient than benzophenone (BP), in which the polymerization rate is almost four times as high as that of the BP system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A water‐soluble supramolecular‐structured photoinitiator between methylated β‐cyclodextrin and 2,2‐dimethoxy‐2‐phenylacetophenone

A water‐soluble supramolecular‐structured photoinitiator (SSPI) was synthesized by supramolecular self‐assembling between methylated β‐cyclodextrin (MβCD) and hydrophobic 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA). The structure of SSPI was characterized by X‐ray diffraction, FTIR, ¹H NMR, UV–vis, and fluorescence spectra. The results indicated that MβCD and DMPA had formed 1 : 1 inclusion complex in methanol solution. The binding constant (K) for the complex was 7.51 × 10²M^?1. SSPI could be dissolved in water easily and its water‐solubility was 15.3 g/100 mL. SSPI was the more efficient photoinitiator than DMPA for the photopolymerization of acrylamide (AM) in homogeneous aqueous system. The conversion for photopolymerization of trimethylolpropane triacrylate system initiated by SSPI was similar to that initiated by DMPA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis and characteristics of photoactive‐hydrogenated rosin epoxy methacrylate for pressure sensitive adhesives

Hydrogenated rosin epoxy methacrylate (HREM), based on hydrogenated rosin and glycidyl methacrylate (GMA), was synthesized for use as an advanced tackifier in the UV‐crosslinking pressure sensitive adhesives (PSAs) system. The HREM, as a tackifier, contained UV‐curing sites; thus, allowed photopolymerization to occur by UV irradiation. This UV‐curable tackifier, HREM, can improve the curing rate and adhesion performance of UV‐crosslinking PSAs. The characteristics of HREM were analyzed by GPC and DSC and its synthetic mechanism studied using FTIR and ¹H NMR; the characteristic peaks of hydrogenated rosin and GMA vanished, but new peaks for HREM appeared. The PDI and the T_g by DSC were 1 and ?25.6°C, respectively. The photopolymerization of HREM was studied using photo‐DSC. Heat flow was observed during UV irradiation, and the curing rate and conversion both increased with rising photoinitiator content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009