Polyampholyte terpolymers of amphoteric,amino acid‐based monomers with acrylamide and (3‐acrylamidopropyl)trimethyl ammonium chloride

Low‐charge‐density amphoteric copolymers and terpolymers composed of acrylamide, (3‐acrylamidopropyl)trimethyl ammonium chloride, and the amino acid derived monomers (e.g., N‐acryloyl valine, N‐acryloyl alanine, and N‐acryloyl aspartate) were prepared via free‐radical polymerization in aqueous media to yield terpolymers with random charge distributions and homogeneous compositions. Sodium formate (NaOOCH) was employed as a chain transfer agent during the polymerization to suppress gel effects and broadening of the molecular weight distribution. Terpolymer compositions were determined by ¹³C and ¹H NMR spectroscopy. Terpolymer molecular weights and polydispersity indices were obtained via size exclusion chromatography/multi‐angle laser light scattering, and hydrodynamic diameter values were obtained via dynamic light scattering. The solution properties of low‐charge‐density amphoteric copolymers and terpolymers have been studied as a function of solution pH, ionic strength, and polymer concentration. The low‐charge‐density terpolymers display excellent solubility in deionized (DI) water with no phase separation. The charge‐balanced terpolymers exhibit antipolyelectrolyte behavior at pH values ≥(6.5 ± 0.2). As solution pH is decreased, these charge‐balanced terpolymers become increasingly cationic because of the protonation of the anionic repeat units. Charge‐imbalanced terpolymers generally demonstrate polyelectrolyte behavior, although the effects of intramolecular electrostatic interactions (e.g., polyampholyte effects) on the hydrodynamic volume are evident at certain values of solution pH and salt concentration. The aqueous solution behavior (i.e., globule‐to‐coil transition at the isoelectric point in the presence of salt and globule elongation with increasing charge asymmetry) of the terpolymers in the dilute regime correlates well with that predicted by the polyampholyte solution theories of Dobrynin and Rubinstein as well as Kantor and Kardar. Examination of comonomer charge density, hydrogen‐bonding ability, and spacer group (e.g., the moiety separating the ionic group from the polymer chain) indicates that conformational restrictions of the amino acid comonomers result in increased chain stiffness and higher solution viscosities in DI water and brine solutions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4479–4493, 2006     

13Carbon nuclear magnetic resonance of ethylene–propylene–1‐decene terpolymers

Many studies have been reported on the ¹³C NMR characterization of ethylene–α‐olefin copolymers, but only a few have been reported on terpolymers. The incorporation of an α‐olefin into the polyethylene chain changes the structure and, consequently, the properties of the polymer obtained. Looking for new products, we obtained a series of ethylene–propylene–1‐decene terpolymers with the metallocenic system rac‐ethylene bisindenyl zirconium dichloride/methylaluminoxane. We performed a complete ¹³C NMR characterization of these terpolymers qualitatively and quantitatively. Here we present a detailed study of the ¹³C NMR chemical shifts, triad sequence distributions, monomer average sequence lengths, and reactivity ratios for these terpolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2531–2541, 2003     

Cyclocopolymerization of allyl‐acrylate quaternary ammonium salts with diallyldimethylammonium chloride

A series of copolymers of N,N‐dialkyl‐N‐2‐(methoxycarbonyl)allyl allyl ammonium chloride, N,N‐dialkyl‐N‐2‐(ethoxycarbonyl)allyl allyl ammonium chloride, and N,N‐dialkyl‐N‐2‐(t‐butoxycarbonyl)allyl allyl ammonium bromide with diallyldimethylammonium chloride (DADMAC) were prepared in water at 60 °C with 2,2′‐azo‐bis(2‐amidinopropane)dihydrochloride. A strong effect of ester substituents on cyclopolymerization was observed. The methyl and ethyl ester monomers showed high cyclization efficiencies during homopolymerizations and copolymerizations. Unexpectedly, the t‐butyl ester derivatives showed high crosslinking tendencies. Water‐soluble copolymers were obtained only with a decrease in the molar fraction of t‐butyl ester monomer below 30%. Relative reactivities of the allyl‐acrylate monomers in photopolymerizations were compared with the relative reactivity of DADMAC. Allyl‐acrylate monomers were much more reactive than DADMAC; the photopolymerization rate decreased in the following order: N,N‐morpholine‐N‐2‐(t‐butoxycarbonyl)allyl allyl ammonium bromide > N,N‐piperidyl‐N‐2‐(t‐butoxycarbonyl)allyl allyl ammonium bromide > N,N‐dibutyl‐N‐2‐(ethoxycarbonyl)allyl allyl ammonium chloride > N,N‐piperidyl‐N‐2‐(ethoxycarbonyl)allyl allyl ammonium chloride ∼ N,N‐morpholine‐N‐2‐(ethoxycarbonyl)allyl allyl ammonium chloride ∼ N,N‐piperidyl‐N‐2‐(methoxycarbonyl)allyl allyl ammonium chloride > N‐methyl‐N‐butyl‐N‐2‐(ethoxycarbonyl)allyl allyl ammonium chloride. Intrinsic viscosities of the polymers measured in 0.09 M NaCl ranged from 1.06 to 3.20 dL/g. The highest viscosities were obtained for copolymers of the t‐butyl ester monomers with piperidine and morpholine substituents. The copolymer of the t‐butyl ester with piperidine substituent and DADMAC was hydrolyzed in acid to give a polymer with zwitterionic character. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 640–649, 2001     

Stimuli‐responsive ampholytic terpolymers of N‐acryloyl‐valine,acrylamide, and (3‐acrylamidopropyl)trimethylammonium chloride: Synthesis,characterization, and solution properties

Low‐charge density ampholytic terpolymers composed of acrylamide (AM), (3‐acrylamidopropyl)trimethyl ammonium chloride (APTAC), and N‐acryloyl‐valine were prepared via free‐radical polymerization in 0.5 M NaCl to yield terpolymers with random charge distributions. Sodium formate (NaOOCH) was employed as a chain transfer agent during the polymerization to suppress gel effects and broadening of the molecular weight distribution (MWD). Terpolymer compositions were determined by ¹³C NMR spectroscopy. Terpolymer molecular weights (MWs) and polydispersity indices (PDIs) were obtained via size exclusion chromatography/multi‐angle laser light scattering (SEC‐MALLS). Intrinsic viscosity values determined from SEC‐MALLS data using the Flory–Fox relationship were compared with those determined by low‐shear dilute solution viscometry and found to be in good agreement. SEC‐MALLS experiments allowed examination of radius of gyration‐MW (R_g‐M) relationships and the Mark‐Houwink‐Sakurada intrinsic viscosity‐MW ([η]‐M) relationships for terpolymers. The R_g‐M and [η]‐M relationships indicated little or no excluded volume effects under SEC conditions indicating that the terpolymers were in near theta conditions in an aqueous buffer solution. Potentiometric titration experiments were performed in deionized (DI) water. These studies revealed that the apparent pK_a of the AMVALTAC terpolymers increases with increasing VAL content. The solution properties of low‐charge density ampholytic terpolymers have been studied as functions of solution pH, ionic strength, and polymer concentration. The charge‐balanced terpolymers exhibit polyampholyte behavior at pH values ≥ 6.5. As solution pH is decreased, these charge‐balanced terpolymers become increasingly cationic due to the protonation of the VAL repeat units. Charge‐imbalanced terpolymers generally exhibit polyelectrolyte behavior, although the effects of intramolecular electrostatic interactions (e.g., polyampholyte effects) on the hydrodynamic volume are evident at certain values of solution pH and salt concentration. The solution behavior of the terpolymers in the dilute regime correlates well with that predicted by various polyampholyte solution theories. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3125–3139, 2006     

13Carbon nuclear magnetic resonance of ethylene–propylene–1‐hexene terpolymers

We report the complete ¹³C NMR characterization of a series of ethylene–propylene–1‐hexene terpolymers obtained with the metallocenic system rac‐ethylene bis‐indenyl zirconium dichloride, with different comonomer ratios. A detailed study of ¹³C NMR chemical shifts, triad sequence distributions, monomer‐average sequence lengths, and reactivity ratios for these terpolymers is presented. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2474–2482, 2004     

Synthesis and characterization of ethylene‐propylene‐1‐pentene terpolymers

Ethylene (E), propylene (P), and 1‐pentene (A) terpolymers differing in monomer composition ratio were produced, using the metallocenes rac‐ethylene bis(indenyl) zirconium dichloride/methylaluminoxane (rac‐Et(Ind)₂ZrCl₂/MAO), isopropyl bis(cyclopentadienyl)fluorenyl zirconium dichloride/methylaluminoxane (Me₂C(Cp)(Flu)ZrCl₂/MAO, and bis(cyclopentadienyl)zirconium dichloride, supported on silica impregnated with MAO (Cp₂ZrCl₂/MAO/SiO₂/MAO) as catalytic systems. The catalytic activities at 25 °C and normal pressure were compared. The best result was obtained with the first catalyst. A detailed study of ¹³C NMR chemical shifts, triad sequences distributions, monomer‐average sequence lengths, and reactivity ratios for the terpolymers is presented. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 947–957, 2008     

Stimuli‐responsive cationic terpolymers by RAFT polymerization: Synthesis,characterization, and protein interaction studies

The controlled synthesis and characterization of a range of stimuli responsive cationic terpolymers containing varying amounts of N‐isopropylacrylamide (NIPAM), 3‐(methylacryloylamino)propyl trimethylammonium chloride (MAPTAC), and poly(ethylene glycol)monomethyl methacrylate (PEGMA) is presented. The terpolymers were synthesized using reversible addition‐fragmentation chain transfer (RAFT) polymerization. Compositions of the terpolymers determined using ¹H NMR were in close agreement to the theoretical values determined from the monomer feed ratios. GPC‐MALLS was used to analyze the molecular weight characteristics of the polymers, which were found to have low polydispersities (M_w/M_n 1.1–1.4). The phase transitions were studied as a function of PEGMA and NIPAM content using temperature controlled ¹H NMR and turbidity measurements (UV‐Vis). The relationship between thermal stability and the comonomer ratio of the polymers was measured using thermogravimetric analysis (TGA). Protein interaction studies were performed to determine the suitability of the polymers for biological applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4021–4029, 2008     

Preparation of amphiphilic statistical copolymers of 2‐hydroxyethyl methacrylate with 2‐diethylaminoethyl methacrylate,precursors of water‐soluble copolymers

Statistical copolymers of 2‐hydroxyethyl methacrylate (HEMA) and 2‐diethylaminoethyl methacrylate (DEA) were synthesized at 50 °C by free‐radical copolymerization in bulk and in a 3 mol L^?1 N,N′‐dimethylformamide solution with 2,2′‐azobisisobutyronitrile as an initiator. The solvent effect on the apparent monomer reactivity ratios was attributed to the different aggregation states of HEMA monomer in the different solvents. The copolymers obtained were water‐insoluble at a neutral pH but soluble in an acidic medium when the molar fraction of the DEA content was higher than 0.5. The quaternization of DEA residues increased the hydrophilic character of the copolymers, and they became water‐soluble at a neutral pH when the HEMA content was lower than 0.25. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2427–2434, 2002     

pH‐responsive polyphosphonates using butler's cyclopolymerization

The cationic monomer, N,N‐diallyl‐(diethylphosphonato)methylammonium chloride, and zwitterionic monomer, ethyl 3‐(N,N‐diallylammonio)methanephosphonate, were cyclopolymerized in aqueous solutions using ammonium persulfate or t‐butylhydroperoxide as initiators to afford a cationic polyelectrolyte (CPE) and a polyzwitterion ester (PZE), respectively. The CPE and PZE on acidic hydrolysis of the ester functionalities afforded the same polyzwitterionic acid (PZA): poly[3‐(N,N‐diallylammonio)methanephosphonic acid]. The solution properties of the CPE, pH‐responsive PZE, and PZA were studied in detail by potentiometric and viscometric techniques. Basicity constants of the phosphonate (P?O(OEt)O^?) and amine groups in the PZE and in the conjugate base of the PZE, respectively, were found to be “apparent” and as such follow the modified Henderson–Hasselbalch equation. In contrast to many polycarbobetaines and sulfobetaines, PZE was found to be soluble in salt‐free water as well as salt (including Ca²⁺, Li⁺)‐added solutions, and demonstrated “antipolyelectrolyte” solution behavior. The PZA, on the other hand, was found to be insoluble in salt‐free water, and on treatment with NaOH gave dianionic polyelectrolyte (DAPE) containing trivalent nitrogen and [P?O(O)₂^2?] groups. For the first time, several new phase diagrams of polyethylene glycol‐DAPE aqueous two‐phase systems (ATPSs) have been constructed in the presence of varying proportions of HCl. The ATPSs may find application in affinity partitioning of metal ions because DAPE is expected to be an effective chelator. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of thermosensitive hydrogels from acryloyloxyethyl trialkyl phosphonium chloride–N‐isopropylacrylamide–N,N′‐methylenebisacrylamide terpolymers and their temperature dependence of water absorption

Thermosensitive polymer hydrogels were prepared by the copolymerization of three kinds of acryloyloxyethyl trialkyl phosphonium chlorides (AETRs) with alkyl chains of different lengths, with N‐isopropyl acrylamide (NIPAAm) and N,N′‐methylenebisacrylamide (MBAAm). The water content of the AETR–NIPAAm–MBAAm terpolymers obtained at molar ratios of the crosslinking agent greater than 2 decreased with increasing temperature and decreased sharply around 35 °C. However, the water contents of the AETR–NIPAAm–MBAAm (X/100/1) terpolymers obtained at a molar ratio of 1 of the crosslinking agent increased once with increasing temperature and then decreased from 3 to around 40 °C. The water contents of the AETR–NIPAAm–MBAAm (3/100/1 or 2) terpolymers decreased with the increasing length of alkyl chains in phosphonium groups in the terpolymers. The water contents of the AETR–NIPAAm–MBAAm terpolymers increased by the addition of a small amount of urea and then decreased with increasing urea concentration. However, the water contents decreased abruptly with the addition of NaCl. The AETR–NIPAAm–MBAAm terpolymers exhibited high adsorption for sodium dodecylbenzene sulfonate but no adsorption for sodium benzene sulfonate. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1505–1514, 2001     

First solvent‐free synthesis of poly(N‐methylolacrylamide) via frontal free‐radical polymerization

We report the first synthesis of poly (N‐methylolacrylamide) (PNMA) via free‐radical frontal polymerization (FP) with solid monomers at ambient pressure. The appropriate amounts of reactants (N‐methylolacrylamide) (NMA) and initiator (ammonium persulfate) were mixed together at ambient temperature without solvent. FP was initiated by heating the wall of the tube with a soldering iron, and the resultant hot fronts were allowed to self‐propagate throughout the reaction vessel. Once initiated, no further energy was required for polymerization to occur. To suppress the fingers of molten monomer, a small amount of nanosilica was added. We also produced PNMA with dimethyl sulfoxide (DMSO) or N‐methyl‐2‐pyrrolidone, as solvent by FP, to study the macrokinetics in FP of PNMA without fillers. The front velocity and front temperature dependence on the ammonium persulfate and N‐methyl‐2‐pyrrolidone concentration were investigated. The polymer was analyzed by thermogravimetric analysis. Results show that without postpolymerization solvent removal, waste production can be reduced. Solvent‐free FP could be exploited as a means for preparation of PNMA with the potential advantage of higher throughput than solvent‐based methods. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4322–4330, 2007     

Synthesis,crystalline morphologies,self‐assembly,and properties of H‐shaped amphiphilic dually responsive terpolymers

Novel and well‐defined amphiphilic H‐shaped terpolymers poly(L‐lactide)‐block‐(poly(2‐(N,N‐dimethylamino)ethyl methacrylate) ‐block‐)poly(ε‐caprolactone)(‐block‐poly(2‐(N,N‐dimethylamino)ethyl methacrylate)) ‐b‐poly(L‐lactide) (PLLA‐b‐(PDMAEMA‐b‐)PCL(‐b‐PDMAEMA)‐b‐PLLA) were synthesized by the combination of ring‐opening polymerization, atom transfer radical polymerization, and click chemistry. The H‐shaped amphiphilic terpolymers can self‐assemble into spherical nano‐micelles in water. Because of the dually responsive (temperature and pH) properties of PDMAEMA segments, the hydrodynamic radius of the micelles of the H‐shaped terpolymer solution can be adjusted by altering the environmental temperature or pH values. The thermal properties investigation and the crystalline morphology analysis indicate that the branched structure of the H‐shaped terpolymers and the presence of amorphous PDMAEMA segments together led to the obvious decrease of PCL segments and the complete destruction of crystallinity of the PLLA segments in the H‐shaped terpolymers. In addition, the H‐shaped terpolymer film has better hydrophilicity than linear PCL or triblock polymer of PLLA‐b‐(N₃? )PCL(? N₃)‐b‐PLLA, due to the decrease or destruction of the crystallizability of the PCL or PLLA in the H‐shaped terpolymer and the presence of hydrophilic PDMAEMA segments. These unique H‐shaped amphiphilic terpolymers composed of biodegradable and biocompatible PCL and PLLA components and intelligent and biocompatible PDMAEMA component will have the potential applications in biomedical fields. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Compositional heterogeneity effects in multisticker associative polyelectrolytes prepared by micellar polymerization

An aqueous micellar radical polymerization technique has been used to prepare water‐soluble polyelectrolytes of acrylamide (AM) and sodium 2‐acrylamido‐2‐methylpropanesulfonate (NaAMPS) hydrophobically modified with low amounts (2–4 mol %) of N,N‐dihexylacrylamide (DiHexAM). This synthesis method leads to multisticker polymers, in which the number and length of the hydrophobic blocks vary with the degree of conversion. Kinetic studies show an appreciable compositional heterogeneity for these polymers, in contrast to their neutral analogues (i.e., AM/DiHexAM copolymers). The drift in composition observed for the AM/NaAMPS/DiHexAM terpolymers is attributed to the electrostatic repulsion between the negatively charged growing polymeric chains, located in the aqueous continuous medium, and the anionic sodium dodecyl sulfate micelles, inside of which the hydrophobic monomer is entrapped. It is shown that an optimization of the polymerization process can be achieved, which gives terpolymers of homogeneous and well‐defined compositions. The thickening ability of the hydrophobically modified polyelectrolytes is directly affected by the extent of their compositional heterogeneity: an increase in the sample homogeneity leads to a significant viscosity enhancement and marked elastic properties of the polymer solutions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3261–3274, 2003     

Composition dependence of nanophase‐separated structures formed by star‐shaped terpolymers of the A1.0B1.0CX type

Several hierarchical nanophase‐separated structures have been observed for a series of ABC star‐shaped terpolymers by transmission electron microscopy (TEM) and electron computerized tomography (3D‐TEM). The seven terpolymers synthesized are composed of polyisoprene (I), polystyrene (S), and poly(2‐vinylpyridine) (P), their volume fraction ratios of I:S:P are 1:1:X, where X equals 0.2, 0.4, 0.7, 1.2, 1.9, 3.0, and 4.9, respectively, and additional four samples were prepared by blending each two parent terpolymers. From morphological observation by TEM and tomography, a terpolymer with X of 0.2 shows lamellar structure with spheres at the interface, those with X ranging from 0.4 to 1.9 show cylindrical structures with two‐dimensional tiling, while those with X of 3.0 and 4.9 show hierarchical cylinders‐in‐lamella structure. Two the other terpolymer samples with X of 7.9 and 10 were produced by blending a P homopolymer with the terpolymer I_1.0S_1.0P_4.9, and they both exhibited columnar piled disk cylinders in P matrix. From the comparison of the present results with the predictions by the Monte–Carlo simulation, it was confirmed that the observed nanophase‐separated structures of the ISP star‐shaped terpolymers are mostly in good agreement with the prediction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2277–2283, 2007     

pH‐Responsive ampholytic terpolymers of acrylamide,sodium 3‐acrylamido‐3‐methylbutanoate,and (3‐acrylamidopropyl)trimethylammonium chloride. I. Synthesis and characterization

Low-charge-density ampholytic terpolymers composed of acrylamide, sodium 3-acrylamido-3-methylbutanoate (NaAMB), and (3-acrylamidopropyl)trimethylammonium chloride were prepared via free-radical polymerization in 0.5 M NaCl to yield terpolymers with random charge distributions. NaOOCH was used as a chain-transfer agent during the polymerization to eliminate the effects of the monomer feed composition on the degree of polymerization (DP) and to suppress gel effects and broadening of the molecular weight distribution. The terpolymer compositions were obtained via ¹³C NMR spectroscopy, and the residual counterion content was determined via elemental analysis for Na⁺ and Cl⁻. The molecular weights (MWs) and polydispersity indices (PDIs) were determined via size exclusion chromatography/multi-angle laser light scattering (SEC–MALLS); the terpolymer MWs ranged from 1.3–1.6 × 10⁶ g/mol, corresponding to DPs of 1.6–1.9 × 10⁴ repeat units, with all terpolymers exhibiting PDIs of less than 2.0. Intrinsic viscosities determined from SEC–MALLS data and the Flory–Fox relationship were compared to intrinsic viscosities determined via low-shear dilute-solution viscometry and were found to agree rather well. Data from the SEC–MALLS analysis were used to analyze the radius of gyration/molecular weight (R_g–M) relationships and the Mark–Houwink–Sakurada intrinsic viscosity/molecular weight ([η]–M) relationships for the terpolymers. The R_g–M and [η]–M relationships revealed that most of the terpolymers exhibited little or no excluded volume effects under size exclusion chromatography conditions. Potentiometric titration of terpolymer solutions in deionized water showed that the apparent pK_a value of the poly[acrylamide-co-sodium 3-acrylamido-3-methylbutanoate-co-(3-acrylamidopropyl)trimethylammonium chloride] terpolymers increased with increasing NaAMB content in the terpolymers and increasing ratios of anionic monomer to cationic monomer at a constant terpolymer charge density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3236–3251, 2004     

Temperature‐responsive linear polyelectrolytes and hydrogels based on [2‐(methacryloyloxy)ethyl] trimethylammonium chloride and N‐isopropylacrylamide and their complex formation with potassium hexacyanoferrates (II,III)

Water‐soluble temperature‐responsive polyelectrolytes and hydrogels have been synthesized by γ‐radiation copolymerization of [2‐(methacryloyloxy)‐ethyl]trimethylammonium chloride with N‐isopropylacrylamide. Complex formation of soluble copolymers with potassium hexacyanoferrates (II, III) was studied in aqueous solutions. It was shown that, depending on the concentration and temperature, the formation of soluble or insoluble polycomplexes is observed. The hydrogels show good ability to absorb potassium hexacyanoferrates (II, III) from aqueous solutions. Sorption ability of hydrogels depends on the content of cationic monomer in copolymer and the nature of coordination ion. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 515–522, 2004     

Synthesis and polymerization of 5‐(methacrylamido)tetrazole,a water‐soluble acidic monomer

The reaction of methacryloyl chloride with 5‐aminotetrazole gave the polymerizable methacrylamide derivative 5‐(methacrylamido)tetrazole ( 4 ) in one step. The monomer had an acidic tetrazole group with a pK_a value of 4.50 ± 0.01 in water methanol (2:1). Radical polymerization proceeded smoothly in dimethyl formamide or, after the conversion of monomer 4 into sodium salt 4‐Na , even in water. A superabsorbent polymer gel was obtained by the copolymerization of 4‐Na and 0.08 mol % N,N′‐methylenebisacrylamide. Its water absorbency was about 200 g of water/g of polymer, although the extractable sol content of the gel turned out to be high. The consumption of 4‐Na and acrylamide (as a model compound for the crosslinker) during a radical polymerization at 57 °C in D₂O was followed by ¹H NMR spectroscopy. Fitting the changes in the monomer concentration to the integrated form of the copolymerization equation gave the reactivity ratios r _4‐Na = 1.10 ± 0.05 and r_acrylamide = 0.45 ± 0.02, which did not differ much from those of an ideal copolymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4333–4343, 2002     

Synthesis,characterization, and cross‐linking of a library of statistical copolymers based on 2‐“soy alkyl”‐2‐oxazoline and 2‐ethyl‐2‐oxazoline

The synthesis of statistical copolymers consisting of 2‐ethyl‐2‐oxazoline (EtOx) and 2‐“soy alkyl”‐2‐oxazoline (SoyOx) via a microwave‐assisted cationic ring‐opening polymerization procedure is described. The majority of the resulting copolymers revealed polydispersity indices below 1.30. The reactivity ratios (r_EtOx 1.4 ± 0.3; r_SoyOx = 1.7 ± 0.3) revealed a clustered monomer distribution throughout the polymer chains. The thermal and surface properties of the pEtOx‐stat‐SoyOx copolymers were analyzed before and after UV‐curing demonstrating the decreased chain mobility after cross‐linking. In addition, the cross‐linked materials showed shape‐persistent swelling upon absorption of water from the air, whereby as little as 5 mol % SoyOx was found to provide efficient cross‐linking. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5371,–5379, 2007     

Synthesis of phosphonated copolymers with tailored architecture by reversible addition‐fragmentation chain transfer polymerization (RAFT)

The synthesis by reversible addition‐fragmentation chain transfer (RAFT) polymerization of three phosphonated terpolymers with tailored architecture has been studied. A phosphonated methacrylate (MAUPHOS) was copolymerized with vinylidene chloride (VC₂) and methyl acrylate (MA) to prepare a gradient terpolymer poly(VC₂‐co‐MA‐co‐MAUPHOS). Besides, hydroxyethyl acrylate (HEA) was used as a functional monomer in RAFT polymerization to prepare a statistical poly(VC₂‐co‐MA‐co‐HEA) terpolymer and a diblock poly(VC₂‐co‐MA)‐b‐poly(HEA) terpolymer. The HEA‐containing polymers were then modified with a phosphonated epoxide to introduce the phosphonated group. The control of the polymerization was proven by kinetic studies (evolution of molecular weight vs. conversion) and by a successful block copolymerization. The architecture of the terpolymers was determined by the reactivity ratios of the monomers: terpolymerization of VC₂, MA, and HEA leading to an ideal statistical terpolymer (no composition drift) whereas terpolymerization of VC₂, MA, and the phosphonated methacrylate led to a gradient terpolymer. These terpolymers were characterized by size exclusion chromatography, ³¹P NMR and differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 13–24, 2006     

Synthesis and thermal properties of a novel lactose‐containing poly(N‐isopropylacrylamide‐co‐acrylamidolactamine) hydrogel

An improved, simple, and efficient method for the synthesis of lactose‐containing monomer acrylamidolactamine (LAM) has been reported. Free radical copolymerization of this monomer with N‐isopropylacrylamide (NIPAM) in the presence of the crosslinking reagent N,N′‐methylenebisacrylamide (BisA) (1.2 mol %) proceeded smoothly in an aqueous solution using potassium persulfate (KPS) and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) as the initiating system and gave transparent hydrogels. Reactivity ratios were estimated from copolymerization reactions carried out in solution without BisA crosslinker and at low conversion, by using both linearization and nonlinearization methods. They were found to be r_LAM = 0.75 and r_NIPAM = 1.22. The swelling behavior of the hydrogels was studied by immersion of the hydrogels in deionized water at different temperatures. Equilibrium water uptake was increased when the LAM content was higher than 47 mol %, and reached ≈ 44‐fold with 100 mol % LAM at room temperature. Depending on the composition, the gels showed sharp swelling transitions with small changes in temperature. Differential scanning calorimetry (DSC) was used to characterize the swelling transition and the organization of water in the copolymer hydrogels. The amounts of freezable water in these hydrogels ranged from 81 to 89%, and was not correlated to the content of the sugar monomer. These gels have potential applications as biocompatible materials. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1393–1402, 1999