Allyl ether‐modified unsaturated polyesters for UV/air dual‐curable coatings. I: Synthesis and characterization of the oligomers and their cured films

Allyl ether (AE)‐modified unsaturated polyester oligomers were synthesized from polyethylene glycol (PEG), maleic anhydride (MAH), and trimethylolpropane mono allyl ether (TMPAE), and characterized by Fourier transform infrared (FTIR) spectra. The UV/air dual‐curable coatings were prepared from the oligomers using vinyl ether (VE) as a reactive diluent. FTIR spectra showed that C?C bonds in the coating composition had polymerized partially after cured by UV or air. The investigation of rheological behavior of the dual curable composition suggested that all the systems belonged to pseudoplastic fluid, and the increasing allyloxy content in oligomer resulted in a higher viscosity. Differential scanning calorimetry (DSC) analysis showed that the increasing TMPAE‐PEG molar ratio resulted in lower T_g, and all samples had the same glass transition temperature irrespective of the type of curing. The results of TGA for cured films indicated that UV‐cured film had better thermal stability than the air‐cured one. The air‐cured film showed superior pencil hardness, impact strength, and flexibility to the UV‐cured counterpart. However, the air‐cured film had poor adhesion and electric resistance properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2765–2770, 2004     

Synthesis and cationic photopolymerization of fluorine‐containing vinyl ether monomers for the hydrophobic films

Fluorine‐containing vinyl ether monomer is a combination of UV‐curing technology and low surface energy materials. In this article, a type of fluorine‐containing vinyl ether monomer was synthesized by the reaction of fluorinated alcohols, hexafluorobenzene, 2‐vinyloxy ethanol, and sodium hydride. These monomers exhibit low viscosity and good fluidity. The effect of the fluorine content of the monomers on their UV‐curing behavior was monitored by photo‐differential scanning calorimetry. The photo‐polymerization process was efficient because the double‐bond conversed sufficiently (>85%) and the curing rate was fast (<20 s). In addition, the surface energy of homopolymer and copolymer films was researched. The surface free energy was very low and could even reach 0.92 mJ m^?2. The low surface energy was due to high fluorine content and the diffusion of uncured monomers, which was on the basis of X‐ray photoelectron spectroscopy data and observed conversions. The structure of homopolymers and copolymers was one of the most important influences on the surface free energy and the thermal properties. The copolymers exhibited better thermal stability than the homopolymers. All of these results demonstrated that these monomers are suitable for a wide range of practical applications such as UV coatings, UV inks, and photoresists. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41019.     

A novel UV‐curable epoxy acrylate resin containing arylene ether sulfone linkages: Preparation,characterization, and properties

UV‐curing processes are used in industrial applications because of their advantages such as high‐speed applications and solvent‐free formulations at ambient temperature. UV‐curable epoxy acrylate resins containing arylene ether sulfone linkages (EAAES) were synthesized through the condensation of bis(4‐chlorophenyl)sulphone and bisphenol‐A, followed by end‐caping of epichlorohydrin and subsequently acrylic acid. UV‐cured coatings were formulated with epoxy acrylates, reactive diluents such as pentaerythritol tri‐acrylate and pentaerythritol dia‐crylate and photoinitiator. Fourier transfer infrared, ¹H NMR, and thermal gravimetrical analysis were employed to investigate the structures and thermal properties of the EAs films. The introduction of EAAES into epoxy acrylate substantially improves its thermal properties and thermo‐oxidative stability at high temperatures. In addition, the acrylate containing arylene ether sulfone linkages can also improve pencil hardness and chemical and solvent resistance of the epoxy acrylate. The obtained UV‐curable epoxy acrylate containing arylene ether sulfone linkages is promising as oligomer for UV‐curable coatings, inks, and adhesives in some high‐tech regions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41067.     

Synthesis and antimicrobial properties of a guanidine‐based oligomer grafted with a reactive cationic surfactant through Michael addition

A guanidine‐based oligomer grafted with a reactive cationic surfactant was designed and synthesized through Michael addition in an attempt to combine its antibacterial and emulsification properties. This was also an excellent and efficient strategy for preparing more kinds of guanidine derivatives. Fourier transform infrared spectroscopy, ¹H‐NMR, and ¹³C‐NMR showed that the guanidine‐based oligomer grafted with reactive cationic surfactant was synthesized successfully. The antimicrobial activity and antimicrobial mechanism were investigated with several approaches. The antimicrobial activity results indicated that the introduction of a cationic surfactant into the guanidine‐based oligomer effectively raised the antimicrobial activity and showed a synergistic effect. The UV absorption at 260 nm was used to detect the dynamic antimicrobial process of the modified guanidine oligomer. Further, the results of scanning electron microscopy and atomic force microscopy implied that the antimicrobial mechanism of the modified guanidine oligomer changed the permeability of the cell membrane of the bacteria and caused the leakage of intracellular components of the Escherichia coli cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3489–3497, 2013     

Reactivity of Si‐H and Si‐vinyl end functionalized siloxanes toward PBT: A model system study

Based on a previous model compound study, we investigated the melt reactivity of Si‐H and Si‐vinyl end‐functionalized siloxane oligomers towards polybutylene terephthalate (PBT) in the presence of platinum(0)‐catalyst. We clearly observed grafting of the Si‐H functional oligomer onto PBT and have also indications for grafting of the Si‐vinyl oligomer. The grafting efficiencies and kinetics of both siloxane model compounds are compared and roughly quantified by infrared spectroscopy. This result indicates that the same reactive groups that are used to vulcanize silicone gums at high temperature can also be used to favor compatibility with a polyester matrix, opening perspectives toward polyester‐siloxane thermoplastic elastomers. POLYM. ENG. SCI. 45:1067–1072, 2005. © 2005 Society of Plastics Engineers     

Synthesis and characterization of bio‐based thermosetting resins from lactic acid and glycerol

A bio‐based thermoset resin has been synthesized from glycerol reacted with lactic acid oligomers of three different chain lengths (n): 3, 7, and 10. Lactic acid was first reacted with glycerol by direct condensation and the resulting branched molecule was then end‐functionalized with methacrylic anhydride. The resins were characterized by Fourier‐transform infrared spectroscopy (FT‐IR), by ¹³C‐NMR spectroscopy to confirm the chemical structure of the resin, and by differential scanning calorimetry and dynamic mechanical thermal analysis (DMTA) to obtain the thermal properties. The resin flow viscosities were also measured using a rheometer with different stress levels for each temperature used, as this is an important characteristic of resins that are intended to be used as a matrix in composite applications. The resin with a chain length of three had better mechanical, thermal, and rheological properties than the resins with chain lengths of seven and 10. Also, its bio‐based content of 78% and glass transition temperature of 97°C makes this resin comparable to commercial unsaturated polyester resins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40488.     

Allyl ether‐modified unsaturated polyesters for UV/air dual‐curable coatings. II: UV and air‐curing behavior

The photoinduced and peroxide‐induced polymerization behavior of dual‐curable allyl ether‐modified unsaturated polyester (AUPE) and vinyl ether (VE) used as a reactive diluent for dual‐curable coating have been studied by infrared spectroscopy (IR). For UV curing systems in N₂ atmosphere, the maleate's conversion and total conversion decrease with the increasing of allyloxy content. However, the rate and of copolymerization and conversion of VE are independent of allyloxy concentration. The copolymerization of allyl ether (AE) and vinyl ether occurs in the presence of maleate (MA) under UV irradiation. For air curing, the rate of copolymerization increases with allyloxy content. The ultimate conversion is the same irrespective of the allyloxy concentration. Because the electron‐rich double bond of allyloxy would become an electron‐deficient one through oxidation, the conversion of maleate decreases with increasing of the allyloxy content due to the enhancement of copolymerization of AE with VE. The ATR‐IR showed that different curing mechanisms occur in AUPE/VE system during air‐curing process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2771–2776, 2004     

Synthesis and photo‐curing behaviors of silicon‐containing (vinyl ether)–(allyl ether) hybrid monomers

A series of silicon‐containing (vinyl ether)–(allyl ether) hybrid monomers used in nano‐imprint lithography resists were synthesized and subjected to photo‐initiated polymerization. The surface energies of the monomers and the resulting polymer films were then investigated. The surface energies of the monomers were very low at less than 15 mJ m^–2. The photo‐curing behaviors of the five hybrid monomers were investigated using real‐time Fourier transform infrared spectroscopy. The monomers were sequentially initiated with cationic (PAG201) and mixed (cationic initiator PAG201, radical initiator ITX or TPO) initiators. The vinyl ether double bond polymerized both rapidly and completely, whereas the allyl ether double bond remained when PAG201 was used as the photo‐initiator and polymerized completely with mixed initiators. The different double bonds of the silicon‐containing (vinyl ether)–(allyl ether) hybrid monomer increased the efficiency of the polymerization and overcame the intrinsic limitations of the free radical and cationic polymerization processes, including strong oxygen inhibition, large volume shrinkage and high humidity sensitivity. The five monomers with low viscosity, low surface energy, good thermal stability and good photo‐polymerization properties were suitable for nano‐imprint photoresists. © 2013 Society of Chemical Industry     

Synthesis,characterization, and UV‐curing properties of silicon‐containing (Meth)acrylate monomers

Eight different silicon‐containing (meth)acrylate monomers are synthesized by the substitution reaction of chlorosiloxanes with 2‐hydroxyethyl methacrylate or 2‐hydroxyethyl acrylate. Their molecular structures are confirmed by IR, ¹H‐NMR, and ¹³C‐NMR spectroscopic analyses. The effects of silicon content on the UV‐curing behavior, physical, surface, and thermal properties are investigated. The UV‐curing behavior is analyzed by photo differential scanning calorimetry. The surface free energy of the UV‐cured film is calculated from contact angles measured using the Lewis acid‐base three liquids method. The silicon‐containing (meth)acrylate monomers perform much better than traditional (meth)acrylate monomers on UV‐curing. The silicon‐containing monomers have higher final conversions and fast UV‐curing rates in photopolymerization. The surface free energy decreases with increasing silicon content, because silicon in the soft segment is transferred to the surface, producing a UV‐cured film; this is confirmed by X‐ray photoelectron spectroscopy measurements. All these advantageous properties enable these synthetic silicon‐containing monomers to perform better in applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of oligocaprolactone vinyl ether macromonomers and their use for indomethacin encapsulation in polymer nanoparticles based on polycaprolactone macromonomer–maleic anhydride–N‐vinyl pyrrolidone terpolymers

Oligocaprolactone macromonomers functionalized with vinyl ether have been synthesized by polymerization of ε‐caprolactone in the presence of hydroxy ethyl or butyl vinyl ether and characterised by NMR and Maldi time‐of‐flight mass spectroscopy. These macromonomers have been copolymerized with maleic anhydride and N‐vinyl pyrrolidone to give terpolymers, which have been used to obtain nanoparticles by the phase‐separation‐dialysis method. Previously dissolving indomethacin in the terpolymer solution allows one to encapsulate the drug inside the nanoparticles. Copyright © 2005 Society of Chemical Industry     

Photocuring of a thiol‐ene system based on an unsaturated polyester

To produce a photocurable thiol‐ene system, unsaturated polyester was prepared from the condensation reaction of ethylene glycol, diethylene glycol, and fumaric acid. Diallyl groups were introduced into the ends of the unsaturated polyester by a sequential condensation reaction. The coating formulation studied contained an equimolar ratio of thiol and vinyl groups of the prepared unsaturated polyester, including 1 wt % Irgacure 184. The curing behaviors of the unsaturated polyester with multifunctional thiols were investigated using real‐time FTIR spectroscopy. The rates of disappearance of thiol and vinyl groups of the unsaturated polyester were similar, demonstrating that there was little free‐radical homopolymerization of the internal fumaric group or the end‐capped vinyl ether group during the photocuring process and that the thiol‐ene reaction is the dominant process. The kinetics of the model compounds demonstrated that the reaction of the terminal allyl double bond with the thiyl radical is faster than that of the internal fumaric double bond in the UV curing of the unsaturated polyester. The storage stability of the thiol‐ene system based on unsaturated polyester was effectively increased by the addition of N‐PAL. The Raman spectra revealed that the presence of a multifunctional thiol (penta 3‐MP4) in the coating formulation increased the degree of surface curing due to the chain‐transfer ability of the thiyl radical. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 342–350, 2005     

Synthesis and characterization of methacrylated star‐shaped poly(lactic acid) employing core molecules with different hydroxyl groups

A set of novel bio‐based star‐shaped thermoset resins was synthesized via ring‐opening polymerization of lactide and employing different multi‐hydroxyl core molecules, including ethylene glycol, glycerol, and erythritol. The branches were end‐functionalized with methacrylic anhydride. The effect of the core molecule on the melt viscosity, the curing behavior of the thermosets and also, the thermomechanical properties of the cured resins were investigated. Resins were characterized by Fourier‐transform infrared spectroscopy, ¹³C‐NMR, and ¹H‐NMR to confirm the chemical structure. Rheological analysis and differential scanning calorimetry analysis were performed to obtain the melt viscosity and the curing behavior of the studied star‐shaped resins. Thermomechanical properties of the cured resins were also measured by dynamic mechanical analysis. The erythritol‐based resin had superior thermomechanical properties compared to the other resins and also, lower melt viscosity compared to the glycerol‐based resin. These are of desired characteristics for a resin, intended to be used as a matrix for the structural composites. Thermomechanical properties of the cured resins were also compared to a commercial unsaturated polyester resin and the experimental results indicated that erythritol‐based resin with 82% bio‐based content has superior thermomechanical properties, compared to the commercial polyester resin. Results of this study indicated that although core molecule with higher number of hydroxyl groups results in resins with better thermomechanical properties, number of hydroxyl groups is not the only governing factor for average molecular weight and melt viscosity of the uncured S‐LA resins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45341.     

New coating systems based on vinyl ether‐ and oxetane‐modified hyperbranched polyesters

A series of hyperbranched aliphatic‐aromatic polyesters has been synthesized which contain vinyl ether or oxetane functionalities as curable groups. We investigated the curing behavior of these multifunctional polymers in the presence of reactive diluents in order to analyze the possibility of their application in high solids coatings. The vinyl ether‐modified hyperbranched polyesters with a high degree of modification yield the best coatings. Furthermore, coating systems containing vinyl ether‐modified hyperbranched polyesters and triethyleneglycol divinyl ether (DVE‐3) as reactive diluent showed a better performance compared to those containing 4‐hydroxybutyl vinyl ether (HBVE). Real time FT‐IR studies revealed a high conversion of functional groups (76%) for the cationic curing with DVE‐3. On the other hand, the curing reaction of the functional hyperbranched polymers without the presence of any reactive diluent stopped at 32% conversion of functional groups due to the reduced mobility of the polymer. The vinyl ether‐modified hyperbranched polyester could be cured also radically in the presence of diethyl maleate (DEM) as reactive diluent, whereas the curing of the oxetane‐modified polyesters was very slow and incomplete in all attempts.     

A novel dendritic acrylate oligomer: Synthesis and UV curable properties

An dendritic acrylate oligomer with eight double bonds (DAO) was synthesized by Michael addition reaction of ethylene diamine (EDA) and trimethylolpropane triacrylate (TMPTA) under mild conditions, and was easily separated from the reaction system with methanol. The structure of DAO was characterized by IR, ¹H‐NMR, and elemental analysis. DAO is UV curable oligomer with low viscosity and high curing speed. Its viscosity was 10.85% of that of the linear acrylic oligomers with similar molecule weight (EBECRYL Resin 285). With Darocure 1173 as the photoinitiator, the curing speed of DAO was respectively 7.5 and 10.3 times higher than that of EBECRYL Resin 605 and EBECRYL Resin 285. Furthermore, the effect of the photoinitiator and active diluent on curing speed of DAO UV curing system was studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1018–1022, 2004     

Tandem cationic and sol–gel photopolymerizations of a vinyl ether alkoxysilane

In the present study, a novel single hybrid monomer combining a vinylether and trimethoxysilane groups in the same molecule was synthesized by chemoselective hydrosilation and subjected to UV‐irradiation in the presence of a triarylsulfonium salt. Through the UV‐decomposition of this photoacid generator, two acid‐catalyzed processes occurred simultaneously: the cationic polymerization of the vinyl ether functions and the sol–gel polycondensation of the alkoxysilyl groups, leading to a type II polyvinyl‐polysilicate nanocomposite film. Both reaction kinetics were efficiently monitored by real‐time Fourier transform infrared spectroscopy, and the influence of different key experimental parameters was investigated (laminated conditions, UV irradiation equipment, and film thickness). A particular attention was also given to the complete characterization of the hybrid microstructure by associating ²⁹Si and ¹³C solid‐state NMR. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Synthesis,spectral, and thermal characterization of photoreactive epoxy resin containing cycloalkanone moiety in the main chain

Dual functional epoxy resins were synthesized by solution polycondensation of 2,6‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclohexanone and 2,5‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclopentanone with epichlorohydrin. The synthesized epoxy resins were characterized systematically for their structure by UV, Fourier transform infrared (FTIR), ¹H NMR, and ¹³C NMR spectroscopic techniques. Thermal characterization of synthesized epoxy resins was carried out by thermogravimetric analysis, and differential scanning calorimetry (DSC) under nitrogen atmosphere. The self extinguishing property of synthesized oligomers was studied by determining limiting oxygen index (LOI) values using Van Krevelen's equation. X‐ray analysis showed that the epoxy resins containing cyclopentanone have higher degree of crystallinity. The photoreactive property of the synthesized epoxy resins in solution and film states was investigated by UV–Vis spectroscopy. The photocross‐linking proceeds through the dimerization of olefinic chromophore present in the main chain of the oligomer via 2π + 2π cycloaddition reaction. The influence of photoacid generator on the rate of photocross‐linking of epoxy resin was studied by FTIR. UV irradiation of the epoxy resin in presence of photoacid generator produces aromatic sulfonium cation radicals and aromatic radicals which initiate the cationic ring‐opening polymerization of oxirane ring. The photoreactivity studies of the oligomers by FTIR and DSC indicated the presence of dual functionality in the synthesized epoxy resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Network formation by aza‐Michael addition of primary amines to vinyl end groups of enzymatically synthesized poly(glycerol adipate)

A highly efficient approach for the synthesis of polyester‐based networks via aza‐Michael addition of primary amines to α,β‐unsaturated (vinyl) end groups of poly(glycerol adipate) (PGA) was achieved. By acylation of PGA with 6‐(Fmoc‐amino)hexanoic acid side chains via Steglich esterification, protected amine‐functionalized PGA was obtained. This was followed by the removal of fluorenylmethyloxycarbonyl (Fmoc) protecting groups and the synthesis of PGA‐based networks under catalyst‐free conditions. The successful conjugate addition of primary amines to vinyl end groups and network formation were confirmed using ¹³C magic angle spinning NMR and Fourier transform infrared spectroscopy. Network heterogeneity and defects were quantitatively investigated using ¹H double‐quantum NMR spectroscopy. Finally, a hydrogel was prepared with potential biomedical applications.     

Triethanolamine–azodiisobutyronitrile mixture as a foaming agent for low‐density unsaturated polyester resin manufacturing at a low temperature

A triethanolamine (TEA)–azodiisobutyronitrile (AIBN) mixture was applied to the manufacturing of a low‐density unsaturated polyester resin (LDUPR) at a low temperature ranging from 53 to 66 °C. Hydrogen‐bonding activation in the TEA–AIBN mixture was put forward, and this agreed with the NMR and Fourier transform infrared (FTIR) spectroscopy results. A heat balance in the curing process of a vinyl ester unsaturated polyester resin (UPR) was examined and characterized by differential scanning calorimetry, FTIR spectroscopy, and scanning electron microscopy. The TEA–AIBN mixture decomposed easily because of the hydrogen‐bonding action between TEA and AIBN. The heat release of the activated AIBN decomposition led to the early endothermic polymerization of the vinyl ester UPR. Hydrogen‐bonding activation followed by the heat‐balance process enabled us to manufacture the LDUPR at low temperature. The optimal parameters of LDUPR manufacturing, including a ratio of TEA to AIBN of 0.4 and a dosage of TEA–AIBN mixture of 2.5 phr at a curing temperature of 60 ± 1 °C, were defined by the testing of the apparent density (ρ) and compressive strength of LDUPR. Under these conditions, ρ was 0.39 ± 0.01 g/cm³, and the specific compressive strength was 33.92 ± 1.31 MPa g^?1 cm^?3. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44797.     

UV‐initiated free radical and cationic photopolymerizations of acrylate/epoxide and acrylate/vinyl ether hybrid systems with and without photosensitizer

Various properties of UV‐initiated acrylate/epoxide and acrylate/vinyl ether hybrid photopolymerizations with and without photosensitizer in the presence of free radical and cationic‐type photoinitiators have been determined by dynamic mechanical thermal analysis (DMTA), calorimetric analysis (photodifferential scanning calorimetry, photo‐DSC; and differential scanning calorimetry), and scanning electron microscopy. DMTA experiments revealed that the UV curing of hybrid systems may produce interpenetrating polymer networks. Photo‐DSC analyses indicated that the acrylates polymerized faster than the epoxide and vinyl ether in the hybrid systems; the addition of a photosensitizer, isopropylthioxanthone (ITX), increased the polymerization rate of the epoxide and vinyl ether in the hybrid systems. SEM analysis confirmed that the free radical system seemed to be significantly affected by oxygen inhibition, while the cationic and hybrid systems were not nearly inhibited by oxygen; the presence of photosensitization produced by the addition of ITX enhanced the surface curing of the hybrid systems. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1473–1483, 2004     

UV‐activated hydrosilation reaction for silicone polymer crosslinking

In this article hydrosilation was employed to achieve a fully cured three‐dimensional silicone network. The UV‐activated hydrosilation reaction was investigated focusing on the curing conditions and their relationships to physical properties. After finding the optimum catalyst concentration, it was observed that by decreasing the molecular weight of the vinyl oligomer a slight increase of the T_g value was achieved together with a complete suppression of the Tm. It was possible to fully cure samples up to 4 cm of thickness. The dark curing process was evaluated by FTIR analyses and it was evidenced an important increase on dark‐polymerization, which is dependent on the length of the UV‐irradiation time. This result shows the versatility of UV‐curing technique for silicone network formation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013