Synthesis,photopolymerization and adhesive properties of new hydrolytically stable phosphonic acids for dental applications

Novel monomers 2‐(N‐methylacrylamido)ethylphosphonic acid, 6‐(N‐methylacrylamido)hexylphosphonic acid, 10‐(N‐methylacrylamido)decylphosphonic acid, and 4‐(N‐methylacrylamidomethyl)benzylphosphonic acid have been prepared in good yields for use in dental adhesives. They have been fully characterized by ¹H‐NMR, ¹³C‐NMR, ³¹P ‐ NMR, and by HRMS. All monomers are hydrolytically stable in aqueous solution. Free radical homopolymerizations of these monomers have been carried out in solution of ethanol/water (2.5/1:v/v), using 2,2′‐azo(2‐methylpropionamidine) dihydrochloride (AMPAHC) as initiator. They lead to homopolymers in moderate to excellent yields. Structure of the polymers has been confirmed by SEC/MALLS and ¹H‐NMR spectra. The photopolymerization behavior of the synthesized monomers with N,N′‐diethyl‐1,3‐bis(acrylamido)propane has been investigated by DSC. New self‐etch primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on (N‐methylacrylamido)alkylphosphonic acids assure a strong bond between the tooth substance and a dental composite. Moreover, the monomer with the longest spacer group provides the highest shear bond strength. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7074–7090, 2008     

Synthesis and evaluation of new phosphonic acid‐functionalized acrylamides with potential biomedical applications

Phosphorus‐containing acidic monomers are able to interact with the inorganic phase of mineralized tissues such as enamel, dentin, and bone. From this perspective, three phosphonic acid‐containing acrylamide monomers with different lengths of alkyl chains were synthesized to be used for both self‐etching dental adhesives and mineralized hydrogel scaffolds. Monomers were synthesized by the reaction of α‐aminophosphonates (diethyl aminomethylphosphonate, diethyl 2‐aminobutan‐2‐ylphosphonate, and diethyl 2‐aminooctan‐2‐ylphosphonate) with acryloyl chloride followed by the hydrolysis of phosphonate groups by using trimethylsilyl bromide. The properties such as pH in the range of mild self‐etching adhesives, hydrolytic stability, high rate of copolymerizations with 2‐hydroxyethyl methacrylate (HEMA) and HEMA/glycerol dimethacrylate, giving high‐molecular‐weight polymers on thermal polymerization, and strong decalcification ability of hydroxyapatite make these monomers good candidates for self‐etching adhesives, although no appreciable effect of the number and size of the α‐substituents was observed. Hydrogel scaffolds containing phosphonic acid groups were fabricated, characterized, and mineralized. Altogether, the results suggest that these phosphonic acid‐containing monomers have suitable properties to be used in fabrication of biomaterials for both dental and bone tissue engineering applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2755–2767     

Monomers for adhesive polymers. XV. Synthesis,photopolymerization, and adhesive properties of polymerizable β‐ketophosphonic acids

The novel polymerizable β‐ketophosphonic acids 4 , 8 , 10 , and 16 as well as the 9‐(methacryloyloxy)‐nonylphosphonic acid 20 were synthesized in four to eight steps. They were characterized by ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy and by high‐resolution mass spectra. The free‐radical polymerization of 4 , 8 , 10 , and 16 was carried out in a water/ethanol solution, using 2,2′‐azo(2‐methylpropionamidine)dihydrochloride as initiator. To evaluate the reactivity of the acidic monomers 4 , 8 , 10 , 16 , and 20 , their photopolymerization behavior was investigated by photodifferential scanning calorimeter. Copolymerizations with 2‐hydroxyethyl methacrylate, glycol dimethacrylate, and N,N′‐diethyl‐1,3‐bis‐(acrylamido)propane were studied. The homopolymerization of the corresponding β‐ketophosphonates and their copolymerization with hydroxyethyl methacrylate were also carried out. Self‐etch adhesives based on the β‐ketophosphonic acids 4 , 8 , 10 , and 16 were able to provide high shear bond strengths (SBSs) of dimethacrylate‐based composite to dentin and enamel. The β‐ketophosphonic acid 8 was also shown to exhibit significantly better adhesive properties than the corresponding phosphonic acid 20 . Indeed, the presence of the carbonyl moiety in the β‐position of the phosphonic acid group led to a strong improvement of the composite SBS to dentin and enamel. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3550–3563     

Synthesis,photopolymerization, and adhesive properties of new bisphosphonic acid monomers for dental application

Four new monomers, 3‐(N‐methylacrylamido)propylidenebisphosphonic acid, 3‐(N‐propyl‐acrylamido)propylidenebisphosphonic acid, 3‐(N‐hexylacrylamido)propylidenebisphosphonic acid, and 3‐(N‐octylacrylamido)propylidenebisphosphonic acid, have been synthesized in good yields and fully characterized by ¹H, ¹³C, ³¹P NMR, and HRMS. The copolymerization of these monomers with N,N′‐diethyl‐1,3‐bis(acrylamido)propane (DEBAAP) has been investigated with differential scanning calorimetry. These mixtures show a higher reactivity than DEBAAP. New self‐etch dental primers, based on these acrylamide monomers, have been formulated. Dentin shear bond strength measurements have shown that primers based on these bisphosphonic acids assure a strong bond between the tooth substance and a dental composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5258–5271, 2009     

Synthesis and evaluation of new dental monomers with both phosphonic and carboxylic acid functional groups

Novel dental monomers containing both phosphonic and carboxylic acid functional groups were prepared. The monomers were based on t‐butyl α‐bromomethacrylate (t‐BuBMA) and synthesized in three steps: The reaction of o‐hydroxyaryl phosphonates [diethyl (2‐hydroxyphenyl) phosphonate, tetraethyl (2,5‐dihydroxy‐1,4‐phenylene) diphosphonate and tetraethyl 5,5′‐(propane‐2,2‐diyl)bis(2‐hydroxy‐5,1‐ phenylene) diphosphonate] with t‐BuBMA, the hydrolysis of phosphonate groups to phosphonic acid using trimethyl silylbromide, and the hydrolysis of the t‐butyl groups to carboxylic acid with trifluoroacetic acid. The monomers were solids and soluble in water and ethanol. The structures of the monomers were determined by Fourier transform infrared (FTIR), ¹H, ¹³C, and ³¹P nuclear magnetic resonance (NMR) spectroscopy. The copolymerization behaviors of the synthesized monomers with glycerol dimethacrylate were first investigated in bulk using photodifferential scanning calorimetry at 40 °C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as photoinitiator. Then, the solution copolymerization of the monomers with acrylamide in ethanol and water was studied, indicating that the synthesized monomers are incorporated into the copolymers. The acidic nature of the aqueous solutions of these monomers (pH values 1.72–1.87) is expected to give them etching properties important for dental applications. The interaction of the monomers with hydroxyapatite was investigated using ¹³C NMR and FTIR techniques. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1953–1965, 2009     

Synthesis and polymerizations of phosphonated‐bis(methacrylamide)s for dental applications

Novel phosphonate and phosphonic acid‐containing bis(methacrylamide)s were synthesized. The phosphonate‐containing monomers ( 1a and 1b ) were synthesized by amidation of 2‐(2‐chlorocarbonyl‐allyloxymethyl)‐acryloylchloride with diethyl 2‐aminoethylphosphonate and diethyl 1‐aminomethylphosphonate. The phosphonic acid‐containing monomers ( 2a and 2b ) were synthesized by hydrolysis of 1a and 1b with trimethylsilyl bromide (TMSBr). All monomers were liquids and dissolved in water and ethanol. Thermal homopolymerization of 1a and 1b in bulk and solution using 2,2′‐azobis(isobutyronitrile) (AIBN) at 80 °C gave crosslinked polymers indicating low cyclization tendencies of these monomers. They were also homopolymerized using photo‐DSC with 2,2′‐dimethoxy‐2‐phenyl acetophenone (DMPA) as photoinitator, and their maximum rates of polymerization were found to be higher than commercial monomers 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy propyloxy) phenyl] propane (Bis‐GMA) and 2‐hydroxyethyl methacrylate (HEMA), indicating their potential as reactive diluents or crosslinkers in dental materials. In fact, copolymerization with monomer 1a resulted in improvements in photopolymerization kinetics of both Bis‐GMA and HEMA. The acidic nature of the aqueous solutions (pH of 2a : 1.42, 2b : 1.53), stability under aqueous conditions after 1 month of study at 37 °C, interaction of 2a with hydroxyapatite (HAP) as representative of both monomers, and copolymerizability of the same with HEMA make these monomers suitable as adhesive monomers in dental adhesives, although their low observed reactivities may present a drawback. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and stability study of dental monomers containing methacrylamidoethyl phosphonic acids

Three new dental monomers containing methacrylamidoethyl phosphonic acids were synthesized. The structures of the synthesized monomers were determined with electrospray mass spectrometry (ESMS), Fourier transform infrared, and NMR. The hydrolytic stabilities of the synthesized monomers and a commercial monomer, 2‐methacryloyloxyethyl phosphoric acid (MEP; used as a control), were studied with flow injection (FI)/ESMS, ¹H NMR, and ³¹P NMR analysis of a CD₃OD/D₂O (4:1 v/v) solution of each monomer before and after storage at 60 °C for 2 months. The ¹H NMR and ³¹P NMR chemical shifts of the monomers 2‐methacrylamidoethylphosphonic acid ( I ) and N,N′‐[4,4′‐(propane‐2,2‐diyl)‐bis(phenoxy‐2‐hydroxypropyl)]‐bis(2‐methacrylamidoethylphosphonic acid) ( II ) showed little change after storage at 60 °C for 2 months, but those of MEP changed significantly. FI/ESMS also showed that MEP was nearly completely decomposed, whereas monomers I and II remained largely intact. MEP could react with H₂ZrF₆ to form ternary zirconium fluoride complexes that were partially soluble in methanol, but all the monomers containing phosphonic acids formed precipitates. This study demonstrates that ESMS is a more sensitive and effective method than NMR for studying the hydrolytic stability or degradation of dental monomers. The new monomers containing methacrylamidoethyl phosphonic acids have higher hydrolytic stability than methacrylate phosphate monomers and may be used in dental bonding agents and other dental materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 99–110, 2007     

Synthesis and modeling of new phosphorus‐containing acrylates

New methacrylate monomers containing phosphonic acid or both phosphonic and carboxylic acids were synthesized through the reaction of t‐butyl α‐bromomethyl acrylate with triethyl phosphite followed by the selective hydrolysis of the phosphonate or t‐butyl ester groups with trimethylsilyl bromide and trifluoroacetic acid. The copolymerization of these monomers with 2‐hydroxyethylmethacrylate was investigated with photodifferential scanning calorimetry at 40 °C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as a photoinitiator. Quantum mechanical tools were also used to understand the mechanistic behavior of the polymerization reactions of these synthesized monomers. The propagation and chain‐transfer reactions were considered and rationalized. A strong effect of the monomer structure on the rate of polymerization was observed. The polymerization reactivities of the monomers increased with decreasing steric hindrance and/or increasing hydrogen‐bonding capacity because of the hydrolysis of the phosphonate and the t‐butyl ester groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2574–2583, 2005     

Synthesis and polymerization kinetics of acrylamide phosphonic acids and esters as new dentine adhesives

In restorative dentistry, acrylamide monomers bearing phosphonic acid moieties have proved to be useful species for the formulation of dental self‐etch adhesives since they provide enhanced adhesion to hydroxyapatite and are not subject to hydrolysis, thus potentially improving their adhesive durability. Previous studies have demonstrated that phosphonic acid acrylamides increase the rate of photopolymerization of diacrylamide monomers. To understand whether this rate acceleration is specific to the acrylamide function of the monomer, or due to the phosphonic acid group per se, or is applicable only with a crosslinking reaction, we have synthesized several acrylamide and methacrylate monomers bearing phosphonic acid or phosphonate moieties and studied their photopolymerization kinetics. The acrylamide phosphonic acid was found to accelerate the polymerization rate but similar monomers bearing a phosphonate ester group had a much smaller effect. A similar accelerating effect was observed when the phosphonic acid‐based monomers were copolymerized with a monofunctional acrylamide monomer, excluding the possibility that the rate acceleration might be related to the crosslinking process. This rate effect is also observed when a nonpolymerizable organic phosphonic acid is present in the polymerizing medium. We suggest that the increase of the medium polarity is responsible for this rate enhancement effect. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and polymerization of phosphorus‐containing acrylates

Novel phosphorus‐containing acrylate monomers were synthesized by two different routes. The first involved the reaction of ethyl α‐chloromethyl acrylate and t‐butyl α‐bromomethyl acrylate with diethylphosphonoacetic acid. The monomers were bulk‐ and solution‐polymerized at 56–64 °C with 2,2′‐azobisisobutyronitrile. The ethyl ester monomer showed a high crosslinking tendency under these conditions. The selective hydrolysis of the ethyl ester phosphonic ester compound was carried out with trimethylsilyl bromide, producing a phosphonic acid monomer. In the second route, ethyl α‐hydroxymethyl acrylate and t‐butyl α‐hydroxymethyl acrylate were reacted with diethylchlorophosphate. The bulk homopolymerization and copolymerization of these monomers with methyl methacrylate and 2,2′‐azobisisobutyronitrile gave soluble polymers. The attempted hydrolysis of the monomers was unsuccessful because of the loss of the diethylphosphate group. The relative reactivities of the monomers in the photopolymerizations were also compared. The ethyl α‐hydroxymethyl acrylate/diethylphosphonic acid monomer showed higher reactivity than the other monomers, which may explain the crosslinking during the polymerization of this monomer. The reactivities of other derivatives were similar, but the rates of polymerization were slow in comparison with those of methyl methacrylate. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3221–3231, 2002     

Synthesis and evaluations of bisphosphonate‐containing monomers for dental materials

Two new bismethacrylamide ( 1 , 2 ) and two new methacrylamide ( 3 , 4 ) dental monomers were synthesized. In each group, one monomer contains a bisphosphonate group, the other a bisphosphonic acid group. Monomer 1 and 3 were synthesized by amidation of 2‐(2‐chlorocarbonyl‐allyloxymethyl)‐acryloylchloride and methacryloyl chloride with tetraethyl aminomethyl‐bis(phosphonate) and converted to the bisphosphonic acid monomers 2 and 4 by hydrolysis with trimethylsilyl bromide. Monomer 1 (m.p.: 71–72 °C), monomer 3 ( 33–34 °C), and monomer 4 (no m.p.) were obtained as white solids and monomer 2 a viscous liquid, soluble in water. Homopolymerization of 1 gave crosslinked polymers, indicating its low cyclization tendency. The photopolymerization studies indicated that its copolymerizability with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy propyloxy) phenyl] propane and 2‐hydroxyethyl methacrylate (HEMA) without changing their rates and conversions significantly means that it could be used as a biocompatible crosslinker. Although monomer 2 showed low polymerizability, because of its good performance in terms of solubility, hydrolytic stability, hydroxyapatite interaction, acidity, and copolymerizability with HEMA, it shows potential to be used in self‐etching dental adhesives. The thermal polymerization of 3 resulted in soluble polymers and evaluation of monomer 4 in terms of solubility, acidity, and copolymerizability with HEMA indicated its potential as an adhesive monomer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and proton conductivities of phosphonic acid containing poly‐(arylene ether)s

A novel phosphonic acid containing bisphenol was successfully synthesized from phenolphthalein and m‐aminophenylphosphonic acid. A series of homo‐ and copoly‐(arylene ether)s containing phosphonic acid groups were prepared by solution nucleophilic polycondensation. These phosphonic acid containing polymers can readily be dissolved in common organic solvents, such as dimethyl sulfoxide, N‐methyl‐2‐pyrrolidinone, and N‐cyclohexylpyrrolidinone, and can be cast into tough and smooth films. The presence of phosphonic acid pendants in the poly‐(arylene ether)s was confirmed by NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and conductivity measurements. This is the first report on the attachment of phenylphosphonic acid groups as side chains to aromatic polyethers. These poly‐(arylene ether)s had very high glass‐transition temperatures ranging from 254 to >315 °C and high molecular weights. The conductivities of the synthesized polymers were analyzed by the Cole–Cole method, and they ranged from 10^?5 to 10^?6 Scm^?1. The synthesized polymers also exhibited good solution processability. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3218–3226, 2001     

Photopolymerization kinetics of ionic liquid monomers derived from the neutralization reaction between trialkylamines and acid‐containing (meth)acrylates

Polymerizable ionic liquids were synthesized from the neutralization reaction between trialkylamines (tributylamine, trihexylamine, trioctylamine, 2‐(dimethyl‐amino)ethyl acrylate, and 2‐(dimethylamino)ethyl methacrylate) and acid‐containing (meth)acrylates to study the kinetics of their photopolymerization. The ionic liquids formed from acrylic acid and methacrylic acid with trialkylamines showed low or moderate increases in rate compared to their monofunctional analogues. The ionic liquids formed from (meth)acrylic acid and a tertiary amine with a pendant acrylate exhibited rates typical of traditional di(meth)acrylates, although the (meth)acrylates were not covalently attached to the same molecule. All of the phosphate‐based ionic liquids exhibited very rapid polymerization rates and strong dependence on the initial viscosity. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3009–3021, 2007     

Synthesis and characterization of poly(N‐isopropylacrylamide) films by photopolymerization

A novel method used for the preparation of poly(N‐isopropylacrylamide) (PNIPAAm) films of varying crosslink density under homogeneous/heterogeneous conditions is described in this paper. Photopolymerization of the N‐isopropylacrylamide (NIPAAm) monomer in water (homogeneous at ～7°C and heterogeneous at ～40°C) or a mixture of water/ethanol (50:50, heterogeneous at ～7°C) was carried out using 1‐[4‐(2‐hydroxyethoxy)‐phenyl]‐2‐hydroxy‐2‐methyl‐1‐propane‐1‐one (hydrophilic) or 2‐hydroxy‐2‐methyl propiophenone (hydrophobic) photo‐initiator. In order to investigate the effect of temperature and crosslink density, polymerization was carried out at ～7°C [below lower critical soluble temperature (LCST)] and ～40°C (above LCST) using varying amounts of N,N′‐methylene bisacrylamide (BIS) ranging from 1–4 wt%. Degree of swelling (determined by optical microscopy), phase transition temperature [determined by differential scanning calorimetry (DSC)] as well as morphology (scanning electron microscopy) were found to be dependent on solvent system (homogeneous/heterogeneous), temperature of polymerization and crosslink density. Hydrogels prepared at ～7°C using hydrophobic photo‐initiator and water/ethanol (50:50) as solvent, showed much higher degree of swelling at all levels of crosslink density as compared to hydrogel prepared at ～7°C using hydrophilic photo‐initiator and water as solvent. Hydrogels were used for patterning which may find applications in microfluidic devices. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis and photopolymerizations of first monomers with phosphonate and bisphosphonate or phosphonic and bisphosphonic acid functionalities for potential dental applications

The first monomers containing both phosphonate and bisphosphonate (M1) or phosphonic and bisphosphonic acid (M2) functionalities are synthesized, aiming to improve binding abilities of self-etching adhesive systems and composites: An amine having both phosphonate and bisphosphonate functionalities is prepared via Michael addition reaction between diethyl (6-aminohexyl)phosphonate and tetraethyl vinylidene bisphosphonate, its reaction with 2-isocyanatoethyl methacrylate gives M1 which is converted to M2 by selective dealkylation of the phosphonate/bisphosphonate ester groups. Their copolymerization with commercial dental monomers (bisphenol A glycidyl methacrylate, triethylene glycol dimethacrylate, and 2-hydroxyethyl methacrylate) investigated by photo-differential scanning calorimetry shows adequate photopolymerization rate and conversion. X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy analyses of M2-treated hydroxyapatite particles show formation of stable M2-calcium salts. These monomers are assessed to be not toxic according to MTT standards by in vitro cytotoxicity studies with NIH 3T3, U2OS, and Saos-2 cells. All these properties make these monomers potential candidates as biocompatible components for dental adhesives and composites. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2739–2751     

Synthesis and photopolymerization of new dental monomers from o‐hydroxyaryl phosphonates

Novel aromatic mono‐ and diphosphonate monomers based on t‐butyl α‐bromomethacrylate were prepared for use in dental composites. The synthesis of the two monomers involved three steps: the reaction of diethyl phosphite with phenol or hydroquinone, the rearrangement of the resulting phosphate derivatives into o‐hydroxyaryl phosphonates with lithium diisopropylamide, and the reaction of o‐hydroxyaryl phosphonates with t‐butyl α‐bromomethacrylate. Then, the selective hydrolysis of the t‐butyl ester groups of the monomers with trifluoroacetic acid gave the other carboxylic acid containing monomers. The photopolymerization behaviors of the synthesized monomers with glycerol dimethacrylate and triethylene glycol dimethacrylate were investigated with photodifferential scanning calorimetry at 40 °C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as the photoinitiator. The hydrolysis of the t‐butyl groups of the monomers increased the reactivity and the rates of polymerization of the monomers. The mixtures of the acid monomers showed rates of polymerizations similar to those of homopolymerizations of triethylene glycol dimethacrylate and glycerol dimethacrylate. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6775–6781, 2006     

Synthesis and properties of fluorine‐containing poly(aryl ether oxadiazole)s

Fluorine‐containing poly(aryl ether 1,3,4‐ozadiazole)s were synthesized by the nucleophilic aromatic substitution reaction of 2,5‐bis(2,3,4,5,6‐pentafluorophenyl)‐1,3,4‐oxadiazole and various bisphenols in the presence of potassium carbonate. The polymerizations were carried out at 30 °C in 1‐methyl‐2‐pyrrolidinone to avoid the gelation caused by a crosslinking reaction at para and ortho carbons to the 1,3,4‐oxidiazole ring. The obtained polymers were all para‐connected linear structures. The obtained fluorine‐containing poly(aryl ether 1,3,4‐ozadiazole)s showed excellent solubility and afforded tough, transparent films by the solution‐casting method. They also exhibited a high glass transition temperature depending on the molecular structure, and the glass transition temperature could be controlled by the bisphenols in the range of 157–257 °C. They showed good thermal stability and excellent hydrophobicity due to the incorporation of the 2,3,5,6‐tetrafluoro‐1,4‐phenylene moiety. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2855–2866, 2007     

Synthesis and photopolymerizations of new phosphonated monomers for dental applications

Three novel phosphonated methacrylate monomers have been synthesized and studied for use in dental applications. Two of the monomers were synthesized from the reactions of glycidyl methacrylate (GMA) with (diethoxy‐phosphoryl)‐acetic acid (monomer 1 ) and (2‐hydroxy‐ethyl)‐phosphonic acid dimethyl ester (monomer 2 ). These monomers showed high crosslinking tendencies during thermal bulk and solution polymerizations. The third monomer (monomer 3 ) was prepared by the reaction of bisphenol A diglycidylether (DER) with (diethoxy‐phosphoryl)‐acetic acid and subsequent conversion of the resulting diol to the methacrylate with methacryloyl chloride. The homopolymerization and copolymerization behaviors of the synthesized monomers were also investigated with glycerol dimethacrylate (GDMA), triethylene glycol dimethacrylate (TEGDMA), and 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxy propyloxy) phenyl] propane (bis‐GMA) using photodifferential scanning calorimetry at 40 °C using 2,2′‐dimethoxy‐2‐phenyl acetophenone (DMPA) as photoinitiator. Monomer 1 showed polymerization rate similar or greater than dimethacrylates studied here but with higher conversion. The maximum rate of polymerizations decreased in the following order: 1 ～TEGDMA>GDMA～bis‐GMA～ 3 > 2 . A synergistic effect in the rate of polymerization was observed during copolymerizations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2290–2299, 2008     

Dynamics of proton exchange in a model phosphonic acid‐functionalized polymer

The dynamics and mechanism of proton exchange in phosphonic acid‐functionalized polymers were studied using poly(vinyl‐phosphonic acid) (PVPA) as a model system along with quantum chemical calculations and Born–Oppenheimer molecular dynamics (BOMD) simulations at the B3LYP/TZVP level as model calculations. This theoretical study began with searching for the smallest, most active polymer segments and their intermediate conformations which could be involved in the local proton‐exchange process. The B3LYP/TZVP results confirmed that a low local dielectric environment and excess proton conditions are required to generate the intermediate conformations, and the shapes of the potential energy curves of the proton exchange between the two phosphonic acid functional groups are sensitive to the local conformational changes. In contrast, a high local dielectric environment increases the energy barriers, thereby preventing the proton from returning to the original functional group. Based on the static results, a mechanism for the proton exchange between the two functional groups involving fluctuations in the local dielectric environment and a local conformational change was proposed. The BOMD results confirmed the proposed mechanism by showing that the activation energies for the proton exchange in the hydrogen bond between two immobilized phosphonic acid moieties, obtained from the exponential relaxation behaviors of the envelopes of the velocity autocorrelation functions and the ¹H Nuclear Magnetic Resonance (NMR) line‐shape analyses, are too low to be the rate‐determining process. Instead, coupled librational motion in the backbone which leads to the interconversion between the two intermediate conformations possesses higher activation energy, and therefore represents one of the most important rate‐determining processes. These findings suggested that the rate of the proton exchange in the model phosphonic acid‐functionalized polymer is determined by the polymer mobility which, in this case, is the large‐amplitude librational motion of the vinyl backbone. © 2015 Wiley Periodicals, Inc.     

Combining poly (methacrylic acid‐co‐ethylene glycol dimethacrylate) monolith microextraction and octadecyl phosphonic acid‐modified zirconia‐coated CEC with field‐enhanced sample injection for analysis of antidepressants in human plasma and urine

A method based on poly (methacrylic acid‐co‐ethylene glycol dimethacrylate) monolith microextraction and octadecylphosphonic acid‐modified zirconia‐coated CEC followed by field‐enhanced sample injection preconcentration technique was proposed for sensitive CE‐UV analysis of six antidepressants (doxepin, clozapine, imipramine, paroxetine, fluoxetine and chlorimipramine) in human plasma and urine. A poly(methacrylic acid‐co‐ethylene glycol dimethacrylate) monolithic capillary column was introduced for the extraction of antidepressants from urine and plasma samples. The hydrophobic main chains and acidic pendant groups of the monolithic column make it a superior material for extraction of basic analytes from aqueous matrix. After extraction, the desorption solvent, which normally provided an excellent medium to ensure direct compatibility for field‐enhanced sample injection in CE, was analyzed by CE directly. By the use of alkylphosphonate‐modified zirconia‐coated CEC for separation of the basic compounds of antidepressants, high separation efficiency and resolution were achieved because that both hydrophobic interaction between analytes and alkylphosphonate‐modified zirconia coat and electrophoretic effect work on the separation of antidepressants. The best separation was achieved using a buffer composed of 0.3 M ammonium acetate (adjusted to pH 4.5 with 1 M acetic acid) and 35% ACN v/v, with a temperature and voltage of 20°C and 20 kV, respectively. By applying both preconcentration procedures, LODs of 11.4–51.5 and 3.7–17.0 μg/L were achieved for the six antidepressants in human plasma and urine, respectively. Excellent method of reproducibility was found over a linear range of 50–5000 μg/L in plasma and urine sample.