Synthesis and viscosity of hydrophobically modified polymers containing dendritic segments

The cycloterpolymerizations of a newly synthesized dendritic quadruple‐tailed hydrophobic diallylammonium chloride with the hydrophilic monomer N,N‐diallyl‐N‐carboethoxymethylammonium chloride and sulfur dioxide afforded a series of water‐soluble cationic polyelectrolytes (CPEs) containing various proportions (0–1 mol %) of the hydrophobe. At a shear rate of 0.36 s^?1 at 30°C, salt‐free water solutions of the CPEs (4 g/dL) containing 0, 0.35, 0.53, 0.65, and 0.93 mol % of the hydrophobe had apparent viscosity values of 140, 1200, 180,000, 308,000, and 858,000 cps, respectively. The study clearly demonstrated an increase in the viscosity values with increasing incorporation of the hydrophobes. The CPEs on acidic hydrolysis of the pendant ester groups gave corresponding pH‐responsive cationic acid salts, which upon treatment with NaOH, were converted to the polybetaines (PBs), anionic polyelectrolytes (APEs), and PB/APEs containing various proportions of PB and APE fractions in the polymer chain. The effects of charge type and charge density on the polymer chain were investigated. Polymer surfactant interactions were investigated with the cationic surfactant cetyltrimethylammonium bromide; a considerable increase in the viscosity values of the CPE was observed in the presence of the surfactant. The superior viscosity behavior for the polymers containing the quadruple‐tailed hydrophobe was attributed to the blocky nature of the comonomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and solution properties of a new ionic polymer and its behavior in aqueous two-phase polymer systems

The amine salt, N,N-diallyl-N-carboethoxymethylammonium chloride was copolymerized in dimethyl sulfoxide using ammonium persulfate or azo-bis-isobutyronitrile (AIBN) to afford the cationic polyelectrolyte (CPE) having five-membered cyclic structure on the polymeric backbone. The CPE on acidic (HCl) hydrolysis of the pendent ester groups gave the corresponding cationic acid salt (CAS) having the equivalent of chloride salt of N,N-diallylammonio ethanoic acid as monomeric unit. The CAS was converted into an anionic polyelectrolyte (APE) and polybetaine (PB) [having the monomeric unit equivalent of sodium N,N-diallylaminoethanoate and N,N-diallylammonioethanoate] by treatment with two and one equivalent of base, respectively. The solution properties of APE were investigated by potentiometric and viscometric techniques. Basicity constant of the amine functionality in APE is found to be ‘apparent’ and as such follow the modified Henderson-Hasselbalch equation; the protonation of the APE becomes more and more difficult as the degree of protonation (α) of the whole macromolecule increases. The composition and phase diagram of the aqueous two-phase systems of APE and poly(ethyelene glycol) (PEG) has been studied for the first time for this class of ionic polymers. The CAS and PB were found to be virtually insoluble in water.     

The effects of charge densities on the associative properties of a pH-responsive hydrophobically modified sulfobetaine/sulfur dioxide terpolymer

Sulfur dioxide, zwitterionic monomer, 3-(N,N-diallylammonio)propanesulfonate and a hydrophobic monomer N,N-diallyl-N-octadecylammonium chloride were cycloterpolymerized in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator to afford water-insoluble polysulfobetaines (PSB) in excellent yields. The PSBs were converted into the corresponding anionic polyelectrolyte (APE) by treatment with 1 equiv. of sodium hydroxide. Treating the pH-responsive PSB polymers with different equivalents of NaOH varied the zwitterionic and anionic charge densities in the polymer chain. The polymer chains with zwitterionic fraction greater than 0.5 were found to be insoluble in water. The solution properties of the APE and PSB/APE systems containing varying amount of the hydrophobic monomers in the range 0-10 mol% were investigated by viscometric techniques. It was found that PSB/APE polymer with a ratio of 33:67 for the zwitterionic and anionic fractions in the polymer chains, respectively, gave the highest viscosity value. The polymer concentration (C*_HA) of around 1 g/dl was required for the manifestation of significant hydrophobic associations. The polymer solutions exhibited sharp increase in viscosity with increasing polymer concentrations in salt (NaCl)-free as well as salt-added solutions. The presence of sodium chloride is shown to enhance intermolecular associations in polymers having hydrophobes in the lower mol% range, whereas, intramolecular associations were manifested in polymers containing higher proportions of the hydrophobes.     

Synthesis and solution properties of a new pH-responsive polymer containing amino acid residues

The amine salt, N,N-diallyl-N-carboethoxymethylammonium chloride was cyclopolymerized in water using ammonium persulfate as an initiator to afford a cationic polyelectrolyte which on acidic hydrolysis of the pendant ester groups gave the corresponding cationic acid salt (CAS). The CAS was converted into an anionic polyelectrolyte (APE) and polybetaine (PB). The solution properties of the APE having two basic functionalities were investigated in detail by potentiometric and viscometric techniques. Basicity constants of the amine as well as the carboxylate groups in APE are ‘apparent’ and as such follow the modified Henderson-Hasselbalch equation; as the degree of protonation (α) of the whole macromolecule increases, the protonation of the amine nitrogens and carboxylate groups becomes increasingly more difficult and easier, respectively. While the APE, PB and CAS were found to be soluble in salt-free water, the corresponding PB and CAS of the SO₂ copolymers of the amine salt 1 were found to be insoluble in water.     

Synthesis of a diallylammonio propanephosphonate‐alt‐(sulfur dioxide) copolymer and its evaluation as an antiscalant in desalination plants

The cationic monomer N,N‐diallyl‐3‐(diethylphosphonato)propylammonium chloride was cyclo‐copolymerized with sulfur dioxide in dimethylsulfoxide using azoisobutyronitrile as initiator to afford a cationic polyelectrolyte (CPE) having a (diethylphosphonato)propyl pendent moiety. The CPE on acidic hydrolysis of the diester groups gave pH‐responsive polyzwitterionic acid (PZA) which on treatment with one and two equivalents of NaOH gave zwitterionic/anionic polyelectrolyte (ZAPE) and dianionic polyelectrolyte (DAPE), respectively. The solution properties of CPE, PZA, ZAPE and DAPE were investigated in detail using a viscometric technique. For comparison, the solution properties of the polymers were correlated with those of the structurally similar polyzwitterion prepared from copolymerization of the corresponding zwitterionic monomer ethyl‐3‐(N,N‐diallylammonio)propanephosphonate and sulfur dioxide. Evaluation of antiscaling properties using concentrated brine solutions revealed that DAPE at a meagre concentration of 10 ppm is very effective in inhibiting the formation of calcium sulfate scale, and as such can be used effectively as an antiscalant in reverse osmosis plants. © 2013 Society of Chemical Industry     

Synthesis and solution properties of hydrophobically associating ionic polymers made from diallylammonium salts/sulfur dioxide cyclocopolymerization

Sulfur dioxide, N,N-diallyl-N-carboethoxymethylammonium chloride and the hydrophobic monomers N,N-diallyl-N-dodecylammonium chloride or N,N-diallyl-N-octadecylammonium chloride were cyclocopolymerized in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator to afford water-soluble cationic polyelectrolyte (CPE) having five-membered cyclic structure on the polymeric backbone. The CPE on acidic (HCl) hydrolysis of the pendent ester groups gave the corresponding cationic acid salt (CAS) which was converted to the anionic polyelectrolyte (APE) by treatment with sodium hydroxide. The solution properties of the CPE and APE containing varying amount of the hydrophobic monomers in the range 0-10 mol% were investigated by viscometric techniques. The polymers showed that concentration (C^∗_HA) of less than 1 wt% was required for the manifestation of hydrophobic association, and displayed significant hydrophobic association in salt (NaCl)-free as well as salt-added solutions.     

Synthesis of a polyaminophosphonate and its evaluation as an antiscalant in desalination plant

The cationic monomer, N,N‐diallyl‐3‐(diethylphosphonato)propylammonium chloride, was cyclopolymerized in aqueous solutions using t‐butylhydroperoxide (TBHP) or ammonium persulfate (APS) as initiators to afford a cationic polyelectrolyte (CPE) having a (diethylphosphonato)propyl pendent. The CPE on acidic hydrolysis of the diester groups gave pH‐responsive polyzwitterionic acid (PZA) which on treatment with one and two equivalents NaOH gave zwitterionic/anionic polyelectrolyte (ZAPE) and dianionic polyelectrolyte (DAPE), respectively. The solution properties of the CPE, PZA, ZAPE, and DAPE were investigated in detail by viscometric technique. For the purpose of comparison, the solution properties of the polymers were correlated to a structurally similar polyzwitterion (PZ) having monoethylphosphonate and NH⁺ groups. When performance evaluation was carried out for application in reverse osmosis (RO) plants, DAPE at a concentration of 10 ppm in brackish water feed proved very effective as an inhibitor against calcium sulfate scale. POLYM. ENG. SCI., 54:166–174, 2014. © 2013 Society of Plastics Engineers     

Solution properties of a hyamine based on N,N‐dimethyl diallyl ammonium chloride–acrylamide copolymer

A hyamine based on N,N‐dimethyl diallyl ammonium chloride–acrylamide copolymer was successfully synthesized in this study. Solution properties of this hyamine including electrical conductivity and viscosity behavior were studied in detail, and effects of temperature and counter ion concentration on electrical conductivity of the solution were also discussed. It was found that a solution of hyamine in water showed a typical viscosity behavior of polyelectrolytes, which followed the Fuoss equation. With the increase of ion radius (cationic ion or anionic ion), or with the increase of salt concentration, the shrinkage degree of the polymer chain increased, with a concomitant decrease in reduced viscosity and intrinsic viscosity and an increase of Huggins constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 765–771, 2003     

Synthesis and comparative solution properties of a cationic polyelectrolyte and its corresponding polyzwitterion from 1,1‐diallyl‐4‐methoxycarbonylpiperidinium chloride

The quaternary ammonium monomer 1,1‐diallyl‐4‐methoxycarbonylpiperidinium chloride was synthesized in good yield. On polymerization in water using t‐butylhydroperoxide as initiator, a cationic polyelectrolyte (CPE) with a five‐membered cyclic structure on the polymeric backbone was obtained. On acid hydrolysis, followed by basification, the CPE gave the corresponding polybetaine (PB). The solution properties of these polymers were investigated by potentiometric and viscometric techniques. The PB demonstrated “antipolyelectrolyte” behavior. The basicity constant of the carboxylate functionality in the polyzwitterionic polymers was ‘apparent’ in a 0.1 N NaCl solution and followed the modified Henderson‐Hasselbalch equation. It was found that as the degree of protonation (α) of the whole macromolecule increases, the protonation of the amine nitrogen becomes increasingly more difficult. Unlike other polyzwitterions/polybetaines, the PB was soluble in salt‐free water. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rheological behavior of pH‐responsive associating ionic polymers of diallyammonium salts and sulfur dioxide

In this study, the viscoelastic behavior of hydrophobically modified polyelectrolytes obtained from the hydrolysis of cationic acid salts (CAS's) as a function of their zwitterion fraction (x) and anion fraction (z) was studied. The dynamic viscosity (η′) dependence on frequency of polymer solutions of polybetaine/anionic polyelectrolyte (APE) with various compositions of x and z in 0.1N NaCl showed typical shear thinning behavior. η′ of a solution of CAS 4 (M₂‐4 (4 mol % hydrophobe)) attained a maximum value in the presence of 1.67 equiv of NaOH (corresponding to an x : z ratio of 33 : 67) and decreased with any further addition of NaOH. We suggest this maximum to be a result of a combined effect of coil expansion and hydrophobic association. The influence of the temperature and concentration on η′ of CAS 4 (M₂‐4) treated with 1.67 equiv of NaOH was also investigated. The rheology of CAS 4 (M₂‐4) samples treated with 1.67, 1.81, and 2.0 equiv of NaOH suggested a reversible network. However, for APE 7 (M₂‐5 (5 mol % hydrophobe)), elastic behavior was dominant, and the formation of highly interconnected three‐dimensional networks was suggested. At lower x : z ratios, the effect of coil expansion due to a higher APE fraction was more than counterbalanced by the lower degree of intermolecular hydrophobic associations, whereas at higher x : z ratios, coil contraction became the predominant effect. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The pH‐responsive cycloterpolymers of diallyldimethylammonium chloride, 3‐(N,N‐diallylammonio)propanesulfonate,and sulfur dioxide

The cycloterpolymerizations of diallyldimethylammonium chloride, 3‐(N,N‐diallylammonio)propanesulfonate, and sulfur dioxide afforded a series of pH‐responsive cycloterpolymers in excellent yields. The solution properties of these ionic polymers were controlled by the composition of the monomeric units; exhibiting dominance either in polyzwitterionic or cationic character. The unquenched valency of nitrogen in the monomeric units of the sulfobetaine zwitterions has permitted these cationic/zwitterionic polymers to be converted into a series of polyampholytes with a charge asymmetry arising out of excess of either the cationic or anionic centers. The water‐solubility of these polymers, upon low‐ and high‐salt (NaCl) additions has been investigated to provide critical solution concentrations to promote water‐insolubility and ‐solubility. A series of associating polymers of the above two monomers and SO₂ with a hydrophobic incorporation of 3–7 mol % of diallyloctadecylammonium chloride has also been synthesized. The solubility and viscosity of the hydrophobically modified polymers in the polyampholytic form were increased considerably in the presence of anionic surfactant sodium dodecyl sulfate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Cyclopolymerization protocol for the synthesis of a poly(zwitterion‐alt‐sulfur dioxide) to investigate the polyzwitterion‐to‐poly(anion‐zwitterion) transition

The zwitterionic monomer, 3‐(N,N‐diallyl,N‐carboethoxymethylammonio)propanesulfonate, on cocyclopolymerization with sulfur dioxide in DMSO using azoisobutyronitrile as the initiator afforded the polyzwitterion (PZ) copolymer in excellent yields. The PZ on acidic hydrolysis of the ester groups led to the corresponding polyzwitterionic acid (PZA). The pH‐responsive PZA on treatment with sodium hydroxide gave the new poly(eletrolyte‐zwitterion) (PEZ). The solubility, viscosity behaviors, and solution properties of the salt‐tolerant PZ, PZA, and PEZ were studied in detail. Like common PZs, PZ was found to be insoluble in salt‐free but soluble in salt‐added water. The apparent basicity constants of the carboxyl group in PEZ have been determined. As the name implies, the PEZ possesses dual type of structural feature common to both conventional anionic polyelectrolytes and PZs, and its aqueous solution behavior is found to be similar to that observed for a typical alternating anionic‐zwitterionic copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The solution behavior of hydrophobically associating zwitterionic polymer in salt water

The acrylamide‐based hydrophobically associating zwitterionic polymer was prepared, which was composed of dimethyl‐dodecyl‐allyl ammonium chloride as hydrophobic group and carboxyl betaine 2‐(4‐acrylamido‐propyl‐dimethyl ammonic)‐sodium acetate as functional group. Hydrophobically associating polyacrylamide (HAPAM) was also prepared for comparative study. The behaviors of polymers in pure water and salt solutions were investigated by the means of apparent viscosity test, laser light scattering, atomic force microscope, and fluorescence experiments. The viscosities of polymer solution increased with the increasing of salt concentration, which indicated that the addition of salt resulted in significant antipolyelectrolyte effect in the zwitterionic polymer solution. The results of dynamic laser light scattering experiment also showed that the average hydrodynamic diameters of the zwitterionic polymer molecules increased with the increasing of salt concentration. The network structures had been observed by atomic force microscope and the addition of salt strengthened the formation of network structures. The results of fluorescence experiment showed that the addition of salt could enhance the association of hyrophobically zwitterionic polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39707.     

Amphiphilic cycloterpolymers of diallyldimethylammonium chloride,diallyloctadecylammonium chloride,and sulfur dioxide

A hydrophilic monomer (diallyldimethylammonium chloride), a hydrophobic monomer (diallyloctadecylammonium chloride), and sulfur dioxide are cycloterpolymerized in dimethylsulfoxide using azobisisobutyronitrile as the initiator to afford water‐soluble cationic polyelectrolytes having a five‐membered cyclic structure on the polymeric backbone. The molecular weights of the polymers containing varying amounts of the hydrophobic monomer (0–7.5 mol %) are determined by light‐scattering experiments. The solution properties of the series of cationic polyelectrolytes are investigated by viscometric techniques. A polymer concentration (C*_HA) of <1 g/dL is required for the manifestation of hydrophobic associations in these terpolymers containing C₁₈ hydrophobic pendents. This is a notable improvement over the C*_HA values (ca. 15–17 g/dL) for the associating cyclopolymers having a pendant length of C10 to C14. The polymer solutions exhibit a sharp increase in viscosity with increasing polymer concentrations in salt‐free as well as salt‐added solutions. The presence of sodium chloride is shown to enhance the hydrophobic association tremendously. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1298–1306, 2005     

Carboxybetaine,sulfobetaine, and cationic block copolymer coatings: A comparison of the surface properties and antibiofouling behavior

Two different zwitterionic block copolymers (BCs) and a cationic BC were synthesized from the same BC precursor, which consisted of a polystyrene (PS) block and a poly[N‐(3‐dimethylamino‐1‐propyl)acrylamide] block. The zwitterionic BCs contained the dimethylammonioacetate (carboxybetaine) and dimethylammoniopropyl sulfonate (sulfobetaine) groups. Thin films cast from these polymers were investigated for surface wettability, surface charge, and protein adsorption. Surface‐energy parameters calculated with advancing contact angle (θ_a) and receding contact angle (θ_r) of different probe liquids showed that it was θ_r and not θ_a that was representative of the polar/ionic groups in the near‐surface regions of the coatings. Electrophoretic mobility was used to characterize the influence of pH on the net surface charge. In aqueous dispersions, the carboxybetaine polymer showed an ampholyte behavior with an isoelectric point of 6, whereas the sulfobetaine polymer was found to be anionic at all pH values between 2 and 10. Protein adsorption on the carboxybetaine BC was relatively independent of the net charges on the protein or the polymer, but the negatively charged sulfobetaine polymer showed a higher adsorption of positively charged protein molecules. Regardless of the net protein charge, both zwitterionic coatings adsorbed less protein compared to the PS and poly(2,3,4,5,6‐pentafluorostyrene) controls. The sulfobetaine and cationic BCs adsorbed higher amounts of oppositely charged protein molecules than like‐charged protein molecules. However, the adsorption of oppositely charged protein was much higher on the cationic surface than on the sulfobetaine surface. The zwitterionic BCs, particularly the carboxybetaine polymer, from this article are expected to function as stable, low‐fouling surface modifiers in different biological environments. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Monitoring the stability of nanosized silica dispersions in presence of polycations by a novel centrifugal sedimentation method

The stability of Aerosil‐silica dispersions is analyzed in dependence on the addition of polycations with different charge density and hydrophobic modification using the analytical centrifuge LUMiSizer. This novel centrifugal sedimentation method allows the direct calculation of the stability parameters like sedimentation velocity and prediction of the shelf life. The highly charged polycation poly (diallyl‐dimethylammonium chloride) (PDADMAC) is compared with tailored cationic polyelectrolytes of equal degree of polymerization but lower and different charge density as well as various hydrophobic substitutions. The used technique allows to accelerate demixing and to quantify the stability of dispersions in a direct way. All polymers under study are able to stabilize aerosil dispersions, but the shelf life strongly depends on the polymer concentration. Typically for polycations, the stability increases with the polymer concentration whereas at low‐polymer content flocculation can be detected. In this context, the behavior of PDADMAC and three cationic PVB derivatives is similar, but, whereas the stability of PDADMAC containing dispersions decreases at higher polymer concentrations, PVB derivatives are effective stabilizers at higher concentrations too. The highest increase of the stability with increasing polymer concentration is obtained with the ampholytic terpolymer TP that has the lowest cationic charge. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Diallyl‐1,12‐diaminododecane‐based cyclopolymers and their use as inhibitors for mild steel corrosion

A variety of N,N‐diallyl compounds, capable of undergoing cyclopolymerization, are prepared from 1,12‐dodecanediamine. Selective monoformylation followed by allylation of the parent diamine afforded N,N‐diallyl‐N′‐formyl‐1,12‐dodecanediamine which was converted into quaternary ammonium monomers N,N‐diallyl‐N‐benzyl (or p‐methoxybenzyl)‐N′‐formyl‐1,12‐dodecanediamine by reacting with benzyl‐ or p‐methoxybenzyl chloride. The monomers on homo‐ and co‐cyclopolymerization (with SO₂) afforded the cationic polyelectrolytes which on acidic hydrolysis of the formyl group gave water‐soluble polyelctrolytes. All the synthesized monomers, polymers, and the starting 1,12‐dodecanediamine were used to study the corrosion inhibition of mild steel by gravimetry and electrochemical methods in acidic and saline media at 60°C. The inhibitor molecules (at a concentration of 400 ppm) exhibited inhibition efficiencies (%IE) in the ranges 62%–99% in 1 M HCl, 95%–99% in 4 M HCl, 13%–91% in 7.7 M HCl, 13%–91% in 0.5 M H₂SO₄, and 75%–90% in 3.5% NaCl. There is a dramatic increase in the IEs by the monomers and polymers in comparison to the parent diamine. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Ionic graft copolymerization. VI. Graft copolymerization of β-propiolactone and N-vinylcarbazole onto trunk polymer containing carboxylic acid,sulfonic acid,and their salts

It was pointed out in previous papers that both cationic and anionic polymerization might be involved simultaneously in grafting onto trunk polymers containing ? COOH or ? SO₃Na. The graft copolymerization of β-Propiolactone (βPL)–N-vinylcarbazole (NVCZ) onto styrene-divinylbenzene copolymers containing carboxylic acid, sulfonic acid, and their salts was carried out in order to distinguish between the polymers produced by anionic and cationic mechanisms. The polymer obtained by the polymerization of βPL–NVCZ with BF₃·OEt₂, a typical cationic catalyst, consisted mainly of NVCZ units, but the polymer obtained with BuLi, a typical anionic catalyst, consisted mainly of βPL units. In the graft copolymerization of NVCZ–βPL onto trunk polymer containing ? COOH, the NVCZ contents of the branch polymer and the tolueneinsoluble fraction were estimated to be ca. 50 mole-%; therefore these polymers were produced by both cationic and anionic mechanisms. In the case of graft copolymerization onto the trunk polymer containing SO₃Na, it was found that both cationic and anionic polymerization also occurred simultaneously.     

Poly(sulfobetaine)s and corresponding cationic polymers. XI. Synthesis and aqueous solution properties of a cationic poly(methyl iodide quaternized ethyl vinyl ether/N,N‐dimethylaminopropyl maleamidic acid) copolymer

A copolymer prepared by the copolymerization of ethyl vinyl ether and maleic anhydride underwent amidoacidation with N,N‐dimethylaminopropylamine. The obtained ethyl vinyl ether/dimethylaminopropyl maleamidic acid copolymer was then reacted with methyl iodide to yield poly(methyl iodide quaternized ethyl vinyl ether/N,N′‐dimethylaminopropyl maleamidic acid) (MIQEDMAPMA). The greatest difference from other polyelectrolytes was the carboxylic group on the polymer chain unit of MIQEDMAPMA. Its aqueous solution properties in various salts and at various pH values were studied by measurements of the reduced viscosity and intrinsic viscosity. The reduced viscosity and intrinsic viscosity of this cationic polyelectrolyte were related to the types and concentrations of the added salts. The tendency of the salt effect was similar to that of other polyelectrolytes; that is, soft salt anions were more easily bound to the quaternary ammonium (R₄N⁺) of MIQEDMAPMA than hard salt anions. Some salt ions strongly attracted the quaternary ammonium of the cationic polymeric side chain for the agglomeration of the polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2261–2269, 2003     

Preparation of antimicrobial polycarboxybetaine‐based hydrogels for studies of drug loading and release

A series of cationic poly(N‐isopropyl acrylamide) (PNIPAM)‐g‐poly(carboxybetaine ester) (PCBMAE) hydrogels were prepared by reversible addition–fragmentation chain‐transfer polymerization with PCBMAE precursors reacting with N‐isopropyl acrylamide in the presence of N,N′‐methylene bisacrylamide. These hydrogels exhibited excellent antimicrobial activities against Staphylococcus aureus and could switch to nontoxic zwitterionic hydrogels after hydrolysis. Nonionic tetracycline hydrochloride (TCHC) and anionic sodium salicylate (SA) were selected to evaluate the loading capacities and release kinetics of the cationic hydrogels. We found that the loading efficiencies of TCHC in the PNIPAM‐g‐PCBMAE hydrogels were approximately twice as high as those of SA. However, the cumulative release amount of TCHC was lower than that of SA from the corresponding cationic hydrogel at 37°C. In addition, the PNIPAM‐g‐PCBMAE hydrogels exhibited accelerated release rates of both TCHC and SA with increasing content of (2‐carboxymethyl)?3‐acryloxyethyldimethylammonium chloride methyl ester. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39839.