Synthesis and antibacterial activities of water‐soluble methacrylate polymers containing quaternary ammonium compounds

New water‐soluble methacrylate polymers with pendant quaternary ammonium (QA) groups were synthesized and used as antibacterial materials. The polymers with pendant QA groups were obtained by the reaction of the alkyl halide groups of a previously synthesized functional methacrylate homopolymer with various tertiary alkyl amines containing 12‐, 14‐, or 16‐carbon alkyl chains. The structures of the functional polymer and the polymers with QA groups were confirmed with Fourier transform infrared and ¹H and ¹³C NMR. The degree of conversion of alkyl halides to QA sites in each polymer was determined by ¹H NMR to be over 90% in all cases. The number‐average molecular weight and polydispersity of the functional polymer were determined by size exclusion chromatography to be 32,500 g/mol and 2.25, respectively. All polymers were thermally stable up to 180 °C according to thermogravimetric analysis. The antibacterial activities of the polymers with pendant QA groups against Staphylococcus aureus and Escherichia coli were determined with broth‐dilution and spread‐plate methods. All the polymers showed excellent antibacterial activities in the range of 32–256 μg/mL. The antibacterial activity against S. aureus increased with an increase in the alkyl chain length for the ammonium groups, whereas the antibacterial activity against E. coli decreased with increasing alkyl chain length. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5965–5973, 2006     

Orthogonally functionalizable copolymers based on a novel reactive carbonate monomer

A novel N‐hydroxy succinimide‐based carbonate monomer that allows direct synthesis of polymers incorporating a reactive carbonate group in the side chain was synthesized. This new monomer was copolymerized with methyl methacrylate and poly(ethylene glycol) methylether methacrylate using free‐radical polymerization to obtain organo‐ and water‐soluble reactive copolymers. Copolymerization of the activated carbonate monomer with an azide‐containing monomer and N‐hydroxy succinimide‐containing activated ester monomer provided orthogonally functionalizable copolymers. The pendant reactive carbonate groups of the copolymers were functionalized with amines to obtain carbamates. Polymers capable of orthogonal functionalization could be selectively functionalized as desired using subsequent 1,3‐dipolar cycloaddition or amidation reactions. The novel monomer and the copolymers were characterized by ¹H‐NMR, ¹³C‐NMR, and infrared spectroscopy. The efficient stepwise orthogonal functionalization of the copolymers were examined via ¹H‐NMR spectroscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

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     

Thermoresponsive micelles from well‐defined block copolymers synthesized via reversible addition–fragmentation chain transfer polymerization

Poly(N‐isopropylacrylamide) (PNIPAAm) homopolymers synthesized by reversible addition–fragmentation chain transfer polymerization were used as macro‐chain‐transfer agents to synthesize smart amphiphilic block copolymers with a switchable hydrophilic–hydrophobic block of PNIPAAm and a hydrophilic block of poly(N‐dimethylacrylamide). All polymers were characterized by gel permeation chromatography, ¹H NMR, and differential scanning calorimetry. The reversible micelles formed by the block copolymers of various compositions in aqueous solutions were characterized by ¹H NMR, dynamic light scattering, and tensiometry. Micelles were observed in the aqueous solutions when the temperature was increased to 40 °C because of the collapse of the PNIPAAm structure, which led to a PNIPAAm hydrophobic block. The drug loading capacity was illustrated with the use of the solvatochromic Reichardt's dye and measured by ultraviolet–visible. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3643–3654, 2005     

Acid‐labile,thermoresponsive (meth)acrylamide polymers with pendant cyclic acetal moieties

Acid‐labile, thermoresponsive polymers with pendant six‐membered cyclic acetal groups were prepared by radical polymerization of two monomers, N‐(2,2‐dimethyl‐1,3‐dioxan‐5‐yl) methacrylamide (NDMM) and N‐(2,2‐dimethyl‐1,3‐dioxan‐5‐yl) acrylamide (NDMA). The aqueous solution properties of the polymers, PNDMM and PNDMA, were studied by turbidimetry, ¹H NMR, fluorescence, and DSC measurements. It is found that both polymers show sensitive and reversible phase transitions with distinct lower critical solution temperatures (LCST). Below their LCSTs, there are still some polymer aggregates as evidenced by measurements of pyrene excitation spectra and urea effects on the cloud points (CP) of polymers. The salting effect of six inorganic sodium salts on the phase transition behavior of PNDMM was investigated by turbidimetric approach. The salting‐out to salting‐in effect is in the order of SO₄^2? > F^? > Cl^? > Br^? > I^? > SCN^?, following the Hofmeister's series. pH‐dependent hydrolysis of PNDMM and PNDMA was studied by turbidimetric and ¹H NMR methods. They are both pH‐sensitive and their hydrolysis rates significantly increase with decreasing pH value. The CP of PNDMM gradually increases with the acid‐triggered hydrolysis of the acetal groups and the hydrolyzed polymer with ～ 30% hydrolysis degree does not show thermally induced phase transition. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4332–4343, 2008     

Atom transfer radical polymerization of styrene using the novel initiator ethyl 2‐N,N‐(diethylamino)dithiocarbamoyl‐butyrate

The atom transfer radical polymerizations (ATRPs) of styrene initiated by a novel initiator, ethyl 2‐N,N‐(diethylamino)dithiocarbamoyl‐butyrate (EDDCB), in both bulk and solution were successfully carried out in the presence of copper(I) bromide (CuBr) and N,N,N′,N″,N″‐pentamethyldiethylenetriamine at 115 °C. The polymerization rate was first‐order with respect to the monomer concentration, and the molecular weights of the obtained polymers increased linearly with the monomer conversions with very narrow molecular weight distributions (as low as 1.17) up to higher conversions in both bulk and solution. The polymerization rate was influenced by various solvents in different degrees in the order of cyclohexanone > dimethylformamide > toluene. The molecular weight distributions of the produced polymers in cyclohexanone were higher than those in dimethylformamide and toluene. The results of ¹H NMR analysis and chain extension confirmed that well‐defined polystyrene bearing a photo‐labile N,N‐(diethylamino)dithiocarbamoyl group was obtained via ATRP of styrene with EDDCB as an initiator. The polymerization mechanism for this novel initiation system is a common ATRP process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 32–41, 2006     

A new cardo bisphenol monomer containing pendant azido group and the resulting aromatic polyesters

Expanding on our strategy to synthesize aromatic step‐growth polymers containing pendant clickable azido groups via functional monomer approach, we have now designed and synthesized a new cardo bisphenol, viz., 2‐(2‐azidoethyl)‐3, 3‐bis(4‐hydroxyphenyl) isoindolin‐1‐one (PPH‐N₃). PPH‐N₃ was conveniently synthesized starting from commercially available phenolphthalein by a three‐step route in an overall yield of 65% using simple organic transformations. Aromatic (co)polyesters bearing pendant azido groups were synthesized by low‐temperature solution polycondensation of PPH‐N₃ or different molar ratios of PPH‐N₃ and bisphenol‐A (BPA) with aromatic diacid chlorides in dry dichloromethane in the presence of triethylamine (TEA) as a base. The formation of medium to reasonably high‐molecular‐weight (co)polyesters was evidenced from intrinsic viscosity and number‐average molecular‐weight measurements that were in the range 0.52–0.85 dL/g and 16,700–28,200, respectively. Tough, transparent, and flexible films could be cast from chloroform solutions of these (co)polyesters. (Co)polyesters were characterized using FTIR, ¹H NMR, ¹³C NMR spectroscopy, XRD, and TGA. The thermal curing reaction of (co)polyesters involving decomposition of azido groups was studied by DSC analysis. The chemical modification of a representative copolyester containing pendant azido groups was carried out quantitatively using catalyst‐free azide‐maleimide cycloaddition reaction with two maleimides, namely, N‐methylmaleimide and N‐hexylmaleimide. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1516–1526     

Synthesis,characterization, and thermal properties of a novel pentaerythritol‐initiated star‐shaped poly(p‐dioxanone)

A novel star‐shaped poly(p‐dioxanone) was synthesized by the ring‐opening polymerization of p‐dioxanone initiated by pentaerythritol with stannous octoate as a catalyst in bulk. The effect of the molar ratio of the monomer to the initiator on the polymerization was studied. The polymers were characterized with ¹H NMR and ¹³C NMR spectroscopy. The thermal properties of the polymers were investigated with differential scanning calorimetry and thermogravimetric analysis. The novel star‐shaped poly(p‐dioxanone) has a potential use in biomedical materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1245–1251, 2006     

Synthesis and properties of sulfonated poly(arylene ether) containing tetraphenylmethane moieties for proton‐exchange membrane

A novel sulfonated poly(arylene ether) containing tetraphenylmethane moieties was successfully synthesized by the sulfonation of a designed parent polymer using chlorosulfonic acid as sulfonation agent. The sulfonation took place only at the para position on the pendant phenyl rings because of the specially designed parent polymer. The sulfonation degree can be easily controlled by using different ratios of sulfonation agent to polymer repeating unit. The position and degree of sulfonation were characterized by ¹H NMR and elemental analysis. The sulfonated polymers are highly soluble in common organic solvents, such as dimethylsulfoxide, N,N′‐dimethylacetamide, dimethylformamide, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The films showed good thermal and hydrolysis stabilities. Moreover, Fenton's reagent test revealed that the membrane exhibited superior stability to oxidation. The proton conductivities of the films were determined to be equivalent with Nafion® 117 under same conditions. The new polymer with sulfonic acid function on pendent phenyl rings can be potentially used as a proton‐exchange membrane for polymer electrolyte membrane fuel cell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6411–6418, 2005     

Hyperbranched polymers generated from oxyanionic vinyl polymerization of commercially available methacrylate inimers

Hyperbranched polymethacrylates were prepared by means of oxyanionic vinyl polymerization of commercially available monomers, including hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) methacrylate (PEG‐MA). Hyperbranched polymethacrylates with high molecular weight were obtained with the complex of potassium hydride and 18‐crown‐6 as the initiator. The effect of 18‐crown‐6 is very important, and only oligomer can be obtained in the polymerization without 18‐crown‐6. The molecular structure of the hyperbranched polymers was confirmed with ¹H NMR and ¹³C NMR spectra. The ratio of initiator to monomer significantly affects the architecture of the resultant polymers. When the ratio of initiator to monomer equals 1 in the oxyanionic vinyl polymerization of HEMA, the degree of branching of the resulting polymer was calculated to be around 0.49. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3502–3509, 2005     

Diselenocarbamates,novel initiators in ATRP of styrene

The atom transfer radical polymerizations (ATRPs) of styrene initiated by diselenocarbamates were carried out for the first time. The polymerization showed first‐order kinetic with respect to the monomer concentration, and the molecular weights of the obtained polymers increased linearly with the monomer conversions with narrow molecular weight distributions (as low as 1.16). The results of chain extension, ¹H NMR, UV–vis, and MALDI‐TOF MS confirmed that the resultant polystyrene possessed some degree of living diselenocarbamates terminal. However, significant amounts of dead polymers (about 53%) were also found. This work offered an alternative type of ATRP initiator, and the seleno‐terminated polymers may be useful in biotechnological and biomedical applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1927–1933     

Concentration effects in the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline in N,N‐dimethylacetamide

The monomer concentration for the cationic ring‐opening polymerization of 2‐ethyl‐2‐oxazoline in N,N‐dimethylacetamide was optimized utilizing high‐throughput experimentation methods. Detailed ¹H‐NMR spectroscopic investigations were performed to understand the mechanistic aspects of the observed concentration effects. Finally, the improved polymerization concentration was applied for the synthesis of higher molecular weight (> 10,000 Da) poly(2‐ethyl‐2‐oxazoline)s. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1487–1497, 2005     

Synthesis of poly(styrene‐block‐tert‐butyl acrylate) star polymers by atom transfer radical polymerization and micellization of their hydrolyzed polymers

A series of poly(styrene‐block‐tert‐butyl acrylate) heteroatom star block copolymers having various block lengths were prepared by atom transfer radical polymerization (ATRP), using an “as synthesized” cynurate modified trifunctional initiator. The structure of the star polymers was confirmed by the characterization of the individual arms resulting from hydrolysis. Amphiphilic poly(styrene‐block‐acrylic acid) star copolymers were further synthesized by hydrolyzing PtBA blocks using anhydrous trifluoroacetic acid. The characterization data are reported from analyses using gel permeation chromatography, infrared, ¹H and ¹³C NMR spectroscopies. The stable micelle solution was prepared by dialyzing the solution of these polymers in N,N‐dimethylformamide against deionized water. The temperature‐induced associating behavior of these amphiphilic star polymers were studied using dynamic laser light scattering spectroscopy. The hydrodynamic diameter of both micelles and unassociated chains were obtained in the same solution using light scattering cumulant's calculation method. The homogeneity and the size distribution of the micelle population in the solution were determined using centrifuge/sedimentation particle size distribution analyzer. Field emission scanning electron microscope was used to visualize the size of the micelles formed and the micellar aggregates. The influence of the temperature on the viscosity of the micelle solution was studied using an Ubbelohde viscometer. Thermodynamics of micellization of these block copolymers were also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6367–6378, 2005     

Branched polystyrene with abundant pendant vinyl functional groups from asymmetric divinyl monomer

Branched polystyrenes with abundant pendant vinyl functional groups were prepared via radical polymerization of an asymmetric divinyl monomer, which possesses a higher reactive styryl and a lower reactive butenyl. Employing a fast reversible addition fragmentation chain transfer (RAFT) equilibrium, the concentration of active propagation chains remained at a low value and thus crosslinking did not occur until a high level of monomer conversion. The combination of a higher reaction temperature (120 °C) and RAFT agent cumyl dithiobenzoate was demonstrated to be optimal for providing both a more highly branched architecture and a higher polymer yield. The molecular weights (M_ws) increased with monomer conversions because of the controlled radical polymerization characteristic, whereas the M_w distributions broadened showing a result of the gradual increase of the degree of branching. The evolution of branched structure has been confirmed by a triple detection size exclusion chromatography (TRI‐SEC) and NMR technique. Furthermore, the double bonds in the side chains were successfully used for chemical modification reactions. ¹H NMR and FTIR measurements reveal that the great mass of pendant vinyl groups were converted to the corresponding objective end‐groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6023–6034, 2008     

Synthesis of a new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxycarbonyl)aminobenzenesulfonamide and its copolymerization with N‐phenyl maleimide

The new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxy‐ carbonyl)aminobenzenesulfonamide (MPBAS) (M₁) is synthesized using sulfadiazine as parent compound. It could be homopolymerized and copolymerized with N‐phenyl maleimide (NPMI) (M₂) by radical mechanism using AIBN as initiator at 60 °C in dimethylformamide. The new monomer MPBAS and polymers were identified by IR, element analysis and ¹H NMR in detail. The monomer reactivity ratios in copolymerization were determined by YBR method, and r₁ (MPBAS) = 2.39 ± 0.05, r₂ (NPMI) = 0.33 ± 0.02. In the presence of ammonium formate, benzyloxycarbonyl groups could be broken fluently from MPBAS segments of copolymer by catalytic transfer hydrogenation, and the copolymer with sulfadiazine side groups are recovered. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2548–2554, 2000     

Side‐chain terpyridine polymers through atom transfer radical polymerization and their ruthenium complexes

Polymers containing side‐chain terpyridine ligands of well‐defined architectures and controllable molecular weights and molecular weight distributions are reported. These polymers were synthesized by the atom transfer radical polymerization (ATRP) of a newly synthesized terpyridine monomer with three functional initiators. The obtained polymers were characterized with ¹H NMR and gel permeation chromatography techniques. The efficiency of the ATRP technique and the overall control of the molecular characteristics of the polymers were demonstrated by a kinetic study of the polymerization reaction. Subsequently, the ruthenium(III)/ruthenium(II) complexation chemistry was employed for the attachment of bis(dodecyloxy)‐functionalized terpyridine moieties onto each side 2,2′:6′,2″‐terpyridine unit of the main polymeric backbone. Thus, the grafting approach was successfully combined with the metal–ligand coordination chemistry for the preparation of highly soluble polymeric complexes. The resulting complexes were fully characterized by means of ¹H NMR, gel permeation chromatography, and ultraviolet–visible spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4838–4848, 2005     

Dendronized polymers with tailored surface groups

A series of polymers tethered with bis‐MPA dendrons was synthesized by a combination of divergent growth and atom transfer radical polymerization (ATRP). Macromonomers of first and second generation were synthesized utilizing the acetonide protected anhydride of bis‐MPA as the generic esterfication agent. The macromonomers were polymerized in a controlled fashion by ATRP utilizing Cu(I)/Cu(II) and N‐propyl‐2‐pyridylmethanamine as the halogen/ligand system. The end‐groups of these polymers were further tailored to achieve hydroxyl, acetate, and aliphatic hexadecyl functionality. With this approach all polymers will emanate from the same backbone, enabling for an evaluation of both the generation and end‐group dependent properties. Furthermore, a dendronized tri‐block copolymer was synthesized. All materials were analyzed by ¹H and ¹³C NMR, as well as size‐exclusion chromatography (SEC). The SEC analysis revealed that the molecular weights of the divergently grown dendronized polymers increased with increasing generation while the polydispersity (PDI) was kept low. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3852–3867, 2005     

Synthesis and characterization of phosphonate‐containing polysiloxanes

Phosphonate‐functionalized polysiloxanes have been prepared with a new siloxane/phosphonate monomer. The reaction of 3‐chloropropylmethyldimethoxysilane with trimethylphosphite or triethylphosphite produces several new monomers containing pendant phosphonate groups. Copolymerization with dimethyldimethoxysilane has produced polymers soluble in most organic solvents. The acid hydrolysis of the phosphoryl esters has produced hydrophilic siloxane polymers containing phosphonic acid groups. The thermal properties of the polymers and several related small molecules have been compared with thermogravimetric analysis. Both the monomers and the resulting polymers have been characterized with ¹H, ¹³C, ³¹P, and ²⁹Si NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 48–59, 2003     

Remarkably stable amphiphilic random copolymer assemblies: A structure–property relationship study

Synthesis of a library of amphiphilic random copolymers from a single reactive pre‐polymer and their self‐assembly is reported. Post‐polymerization modifications of the parent polymer containing pendant N‐hydroxy succinimide (NHS) ester groups with various oligooxyethylene (OE) amines produce amphiphilic random copolymers with same degree of polymerization and equal extent of randomness. ¹H‐NMR and FT‐IR data indicate quantitative substitution in all cases. The critical aggregation concentration (CAC) for all the polymers is estimated to be in the range of 10^?5 M. Stability of these nano‐aggregates is studied by photoluminescence using time dependent F—rster Resonance Energy Transfer (FRET) between co‐encapsulated lipophilic dyes namely DiO and DiI in the hydrophobic pocket of the aggregates. These studies suggest remarkably high stability for all systems. However those with shorter hydrophilic pendant chains are found to be even more robust. Morphology is examined by high resolution transmission electron microscopy (HRTEM) which reveals multi‐micellar clusters and vesicles for polymers containing short and longer OE segments, respectively. Encapsulation efficacy is tested with both hydrophobic and hydrophilic guest molecules. All of them can encapsulate hydrophobic guest pyrene while a hydrophilic dye Calcein can be sequestered only in vesicle forming polymers. Lower critical solution temperature (LCST) is exhibited by only one polymer that contains the shortest OE chains. All polymers exhibit excellent cell viability as determined by MTT assay. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4932–4943     

Organosoluble star polymers from a cyclodextrin core

Well‐defined star polymers were synthesized with a combination of the core‐first method and atom transfer radical polymerization. The control of the architecture of the macroinitiator based on β‐cyclodextrin bearing functional bromide groups was determined by ¹³C NMR, fast atom bombardment mass spectrometry, and elemental analysis. In a second step, the polymerization of the tert‐butyl acrylate monomer was optimized to avoid a star–star coupling reaction and allowed the synthesis of a well‐defined organosoluble polymer star. The determination of the macromolecular dimensions of these new star polymers by size exclusion chromatography/light scattering was in agreement with the structure of armed star polymers in a large range of predicted molecular weights. This article describes a new approach to polyelectrolyte star polymers by postmodification of poly(tert‐butyl acrylate) by acrylic arm hydrolysis in a water‐soluble system. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5186–5194, 2005