The effects of zwitterionic and anionic charge densities in polymer chains on the viscosity behavior of a pH‐responsive hydrophobically modified ionic polymer

Sulfur dioxide, N,N‐diallyl‐N‐carboethoxymethylammonium chloride, and the hydrophobic monomer N,N‐diallyl‐N‐octadecylammonium chloride were cyclocopolymerized in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator to afford water‐soluble cationic polyelectrolytes (CPE) having a five‐membered cyclic structure on the polymeric backbone. The CPE on acidic hydrolysis of the pendent ester groups gave the corresponding cationic acid salts (CAS), which, on treatment with sodium hydroxide, were converted to polybetaines (PB) and anionic polyelectrolytes (APE), as well as polymers PB/APE containing various proportions of zwitterionic (PB) and anionic fractions (APE) in the polymer chain. The solution properties of the CPE, APE, and PB/APE systems containing varying amounts of the hydrophobic monomers in the range 0–4 mol % were investigated by viscometric techniques. Treating the pH‐responsive CAS polymers 4 with different equivalents of NaOH varied the zwitterionic and anionic charge densities in the polymer chain. It was found that the PB/APE polymer with a ratio of 33 : 67 for the zwitterionic and anionic fractions in the polymer chain, respectively, gave the highest viscosity value. The polymers showed that concentration (C*_HA) of around 1 g/dL was required for the manifestation of significant hydrophobic associations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1404–1411, 2005     

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     

Rheological properties of a hydrophobically modified anionic polymer: Effect of varying salinity and amount of hydrophobic moieties

Hydrophobically modified polyelectrolytes have been suggested as an alternative to the more commonly used polyelectrolytes in enhanced oil recovery (EOR) applications involving polymers. Compared to regular polyelectrolytes, the hydrophobically modified polyelectrolytes are known to be more stable at high salinities. In this study, we have investigated the influence of brine salinity and ionic composition for a series of six hydrophobically modified polyelectrolytes with the same polymer backbone, but with an increasing average number of hydrophobic groups per polymer molecule. Polymer characterization has been performed using a combination of steady‐state shear viscosity and dynamic oscillatory measurements. Hydrophobic interactions leading to a change in rheological properties was only observed above a threshold value for the concentration of hydrophobe. At the threshold value, salt‐induced hydrophobic interactions were observed. For higher concentrations of hydrophobe, high salinity solutions showed one order of magnitude increase in viscosity compared to the polymer without hydrophobic groups. This could partly be explained by an increase in elasticity. These findings have important implications for polymer selection for EOR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43520.     

Addressing water scarcity: cationic polyelectrolytes in water treatment and purification

Synthetic cationic polyelectrolytes (CPEs) serve as coagulation and flocculation agents in wastewater treatment due to a synergy of inherent electrostatic interactions and hydrophilic properties. In wastewater treatment, CPEs act as coagulation and flocculation agents to aggregate impurities and enable water purification. New health and environmental‐related regulations provide motivation for government agencies and industrial companies to reuse wastewater. Chemical structure, molecular weight, charge density and functionality of CPEs provide tailorability for specific purification needs. Cationic polyacrylamides, ammonium‐based polymers, poly(allyldimethyl‐ammonium chloride) and epichlorohydrin/dimethylamine‐based polymers are the most common CPEs used as coagulation and flocculation agents because they are economical and water soluble with tunable charge densities at high molecular weights. Free radical polymerization, step‐growth polymerization and post‐polymerization modification methods afford each polymer system. This review highlights recent advancements in synthetic methods to yield CPEs, structure?property relationships as related to flocculation efficiency and a summary of their toxicity and environmental impact. © 2018 Society of Chemical Industry     

Smart anionic polyelectrolytes based on natural polymer for complexation of cationic surfactant

The thermosensitive polyelectrolytes were obtained by grafting 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) onto hydroxypropylcellulose (HPC), a biodegradable polysaccharide. The interactions of the polymers with dodecyltrimethylammonium chloride (DTAC), a model cationic surfactant, were studied. It was found by the measurements of the surface tension and the analysis of fluorescence emission of pyrene used as a fluorescent probe, that the HPC–AMPS graft polymers strongly interact with DTAC with the formation of polymer–surfactant complexes. The critical aggregation concentrations of these polymer–surfactant systems were found to be of the order of 10^?5 mol/dm³. The polymers were found to be potentially useful in the purification of water from cationic surfactants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2401–2407, 2006     

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     

Preparation and solution performance for the amphiphilic polymers with different hydrophobic groups

An amphiphilic polymer with twin‐tailed hydrophobic groups was prepared by micellar polymerization of acrylamide as hydrophilic monomers, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid as functional monomers and N,N‐dodecyl acrylamide as hydrophobic monomers. Using the same method, containing single‐tailed hydrophobic group of the amphiphilic polymer and not containing the hydrophobic group of ordinary polymer were prepared. The molecular structure of the product was characterized by infrared spectrum and ¹H nuclear magnetism resonance spectrum. By inclusion complexation of β‐cyclodextrin (β‐CD), the hydrophobic association on the apparent viscosity contribution rate was studied. Relationship between hydrophobic group structure and its performance was investigated by the rotational viscometer, scanning electron microscopy (SEM), fluorescence spectroscopy, and rheometer. The results showed that amphiphilic polymers containing twin‐tailed hydrophobic groups had a lower critical aggregation concentration (CAC). When the amphiphilic polymer concentration was higher than CAC, hydrophobic association was stronger, which led to a higher apparent viscosity contribution rate. At the same polymer solution concentration, amphiphilic polymer containing twin‐tailed hydrophobic group had better performance on temperature resistance, salt tolerance, and mechanical shear resistance compared with the other two polymers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44744.     

Interactions of a smart cationic polyelectrolyte based on hydroxypropylcellulose with an anionic surfactant

Novel thermosensitive, cationic polyelectrolyte was obtained by grafting N‐vinylformamide onto hydroxypropylcellulose followed by the hydrolysis of the formamide groups to the amine groups. The effect of the ionic strength on the lower critical solution temperature of the polymers was studied. The interactions of the polymers with sodium dodecyl sulfate (SDS) as a model anionic surfactant were studied. It was found by the measurements of the light scattering and fluorescence spectroscopy that the graft copolymers obtained strongly interact with SDS with the formation of polymer‐surfactant complexes. The values of critical association concentration (cac) of these polymer‐surfactant systems were found to be of the order of 10^?5 mol/dm³ at pH = 6.5 and of the order of 10^?6 mol/dm³ at pH = 2.5. The polymer was shown to be potentially useful for the purification of water from anionic surfactants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

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     

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     

Properties of hydrophobically modified polyacrylamide with low molecular weight and interaction with surfactant in aqueous solution

Hydrophobically modified polyacrylamide (HMPAM), with a molecular weight of 10⁴ g/mol, was studied using a range of rheological methods and dynamic light scattering (DLS). DLS measurements indicate that the association of the modified polymer begins at low concentration. The modified polymer with high substitution forms transient networks below the critical concentration, but the networks are disrupted by the micelles formed by the polymer itself, and the networks do not contribute to viscosity enhancement. The modified polymers exhibited surface activity, and so they may be regarded as nonionic polymeric surfactants rather than thickeners. On the other hand, HMPAM is shown to interact with the surfactant SDS while PAM is inert to SDS. In the hydrophobic domains, it undergoes a surfactant‐induced association process; in the hydrophobe‐surfactant transition regions, the surfactant binds to the polymer in a noncooperative way and forms a polymer–surfactant complex. Contracted polymer chains begin to extend because of electrostatic repulsion, which can overcome the association at surfactant domains. The conformation of HMPAM polymer chains could be controlled by adding a specific amount of surfactant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4348–4360, 2006     

Hydrophobically modified acrylamide‐based polybetaines. II. Interaction with surfactants in aqueous solution

The interaction of hydrophobically modified (HM) polybetaines with selected small molecule surfactants in aqueous solution was investigated using rheological and surface tension analyses. The polymers included acrylamide‐based, HM polybetaines containing N‐butylphenylacrylamide (BPAM) and specified amounts of sulfobetaine, 3‐(2‐acrylamido‐2‐methylpropanedimethylammonio)‐1‐propanesulfonate (AMPDAPS), or carboxybetaine, 4‐(2‐acrylamido‐2‐methylpropyldimethylammonio)butanoate (AMPDAB); corresponding control (co)polymers lacking BPAM and/or betaine comonomer(s) were also examined for comparative purposes. Low charge density terpolymers exhibited greater viscosity enhancement with the addition of surfactant compared to the high charge density terpolymers. The addition of sodium dodecyl sulfate (SDS) produced the largest increase in solution viscosity, while N‐dodecyl‐N,N,N‐trimethylammonium bromide (DTAB), N‐dodecyl‐N,N‐dimethylammonio‐1‐propanesulfonate (SB3–12), and Triton X‐100 enhanced polymer solution viscosity to a lesser degree. In most cases, the high charge density carboxybetaine terpolymer exhibited diminished solution viscosity upon surfactant addition. The polymers lacking hydrophobic modification showed no detectable viscosity enhancement in the presence of surfactants. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 658–671, 2004     

Effect of cationic surfactant addition on the drag reduction behaviour of anionic polymer solutions

Although extensive research work has been carried out on the drag reduction (DR) behaviour of polymers and surfactants alone, little progress has been made on the synergistic effects of combined polymers and surfactants. In this work, the interactions between drag‐reducing anionic polymer (copolymer of acrylamide and sodium acrylate, referred to as PAM) and drag‐reducing cationic surfactant (octadecyltrimethylammonium chloride, OTAC) are studied. Solutions are prepared using both deionised (DI) water and tap water. The measurement of the physical properties such as electrical conductivity and viscosity are used to determine the surfactant–polymer interactions. The addition of surfactant to the polymer solution has a significant effect on the properties of the system. The critical micelle concentration (CMC) of the mixed surfactant–polymer system is found to be different from that of the surfactant alone. With the addition of surfactant to a polymer solution, a substantial decrease in the viscosity occurs. The observed changes in the viscosity of mixed polymer–surfactant system are explained in terms of the changes in the extension of polymeric chains, resulting from polymer–surfactant interactions. The anionic PAM chains tend to collapse upon the addition of cationic OTAC. The pipeline flow behaviour of PAM/OTAC mixtures is found to be consistent with the bench scale results. The DR ability of PAM is reduced upon the addition of OTAC. At low concentrations of PAM, the effect of OTAC on the DR behaviour is more pronounced. The DR behaviour of polymer solutions is strongly influenced by the nature of water (DI or tap). © 2011 Canadian Society for Chemical Engineering     

Viscometric Study of the Inclusion Complex Between β‐Cyclodextrin and HTAC in Aqueous Solution

The inclusion complex formed by β‐cyclodextrin (β‐CD) with the cationic surfactant hexadecyltrimethylammonium chloride (HTAC) was studied by viscometry using poly(ethylene oxide) (PEO)–HTAC aggregates as a viscosity indicator. The relative viscosity of β‐CD in aqueous PEO–HTAC solution profiles shows that the formation of the β‐CD/HTAC inclusion complex causes HTAC molecules to be stripped off the PEO chains, resulting in a decrease of aqueous solution viscosity as a result of the decrease in electrostatic repulsion between polymer‐bound HTAC micelles. The viscosity minimum at C_β‐CD/C_HTAC = 0.5 indicates that the molecular ratio of host molecule to guest molecule is 1:2 in the β‐CD/HTAC inclusion complex.     

Phase inversion of polyacrylamide‐based inverse‐emulsions: Influence of inverting‐surfactant type and concentration

The phase inversion of polymeric water‐in‐oil emulsions has been systematically studied by employing nonylphenol and alcohol ethoxylates with various chemistries as well as physical chemical characteristics. A combination of thermodynamics, phase diagrams, and rheometry were used to investigate the behavior of the inverting surfactants as well as the inverted, acrylamide‐based, cationic emulsions. Polymeric inverse‐emulsions containing the inverting surfactant showed no evidence of low‐shear thinning, though they did thin as hydrodynamic forces increased (0.01 to 100 s^?1) prior to reaching a chemistry‐ and concentration‐independent plateau, as is typical for emulsions. The viscosity of emulsions containing inverting surfactants reached a minimum at 1.2% of the “emulsion breaker”. The efficiency of inversion was optimized at 2 wt % of nonylphenols, expressed as a percentage of the total emulsion mass, and increased with the degree of ethoxylation. Interestingly, the viscosity of the polymer inverted in water was maximized at an inverting‐surfactant level corresponding to the CMC of the pure surfactant in water. The alcohol ethoxylates required a higher concentration for inversion (3 wt %), though they provided a higher ultimate inverse viscosity of the polymeric emulsion in water. Therefore, while the inversion process was less efficient with alcohol ethoxylates, the ultimate dilution solution properties of the polyelectrolytes liberated were improved relative to the nonylphenols. Overall, the process of adding a water‐in‐oil emulsion, containing an emulsion breaker, to an excess of water involves a catastrophic inversion mechanism. To be effective under such circumstances, an inverting surfactant should have a partition coefficient between the aqueous an organic phases greatly exceeding unity as well as a hydrophilic–lipophilic balance (HLB) above 12. Effectiveness increases linearly with the partition coefficient. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3567–3584, 2007     

Electrolyte‐ and pH‐responsive polyampholytes with potential as viscosity‐control agents in enhanced petroleum recovery

Low‐charge‐density amphoteric copolymers and terpolymers composed of AM, the cationic comonomer (3‐acrylamidopropyl)trimethyl ammonium chloride, and amino acid derived monomers (e.g., N‐acryloyl valine, N‐acryloyl alanine, and N‐acryloyl aspartate) have been prepared via free‐radical polymerization in aqueous media. These terpolymers with random charge distributions have been compared to terpolymers of like compositions containing the anionic comonomer sodium 3‐acrylamido‐3‐methylbutanoate. Terpolymer compositions determined by ¹³C‐ and ¹H‐NMR spectroscopy, terpolymer molecular weights and polydispersity indices obtained via size exclusion chromatography/multi‐angle laser light scattering, and hydrodynamic dimensions determined via dynamic light scattering have allowed a direct comparison of the fundamental parameters affecting the behavioral characteristics. The solution properties of low‐charge‐density amphoteric copolymers and terpolymers have been studied as functions of the solution pH, ionic strength, and polymer concentration. The low‐charge‐density terpolymers display excellent solubility in deionized water with no phase separation. The charge‐balanced terpolymers exhibit antipolyelectrolyte behavior at pH values greater than or equal to 6.5 ± 0.2. As the solution pH decreases, these charge‐balanced terpolymers become increasingly cationic because of the protonation of the anionic repeat units. 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. An examination of the 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 sodium 3‐acrylamido‐3‐methylbutanoate and N‐acryloyl valine segments result in increased chain stiffness and higher solution viscosities in deionized water and brine solutions. On the other hand, the terpolymers with N‐acryloyl alanine and N‐acryloyl aspartate segments are more responsive to changes in the salt concentration. An assessment of the effects of the terpolymer structure on the viscosity under specified conditions of the ionic strength and pH from these studies should allow for rational design of optimized systems for enhanced petroleum recovery. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007.     

EVA nanocomposites based on South African Koppies clay

South African Koppies bentonite was organomodified with single‐tail and double‐tail alkyl ammonium cationic surfactants with the latter intercalated both below and above the clay cationic exchange capacity. Corresponding poly(ethylene‐co‐vinylacetate) nanocomposites were prepared by twin‐screw melt compounding. Transmission electron microscopy indicated the presence of mixed nano‐sized and micron‐sized clay morphologies. X‐ray diffraction studies revealed that the crystallinity of the particles improved and that the d‐spacing values increased on incorporating the clays in the polymer matrix. It is postulated that, rather than indicating polymer co‐intercalation, this is caused by further intercalation of either excess surfactants or surfactant residues that were released by shear delamination of the clays during compounding. Improved mechanical properties were realized especially when using the clay containing the longer double‐tail surfactant intercalated at levels in excess of the cation exchange capacity of the clay. The nanocomposites showed improved tensile modulus and elongation‐at‐break values at the expense of a reduction in impact strength, whereas tensile strength was about the same as for the neat polymer. J. VINYL ADDIT. TECHNOL., 20:143–151, 2014. © 2014 Society of Plastics Engineers     

Transport properties of some cationic amphiphilic polysaccharides: Effects of the side‐chain length and solvent polarity

The transport properties of polyelectrolytes with N‐alkyl‐N,N‐dimethyl‐N‐(2‐hydroxypropyl)ammonium chloride pendent groups (alkyl = octyl, dodecyl, or cetyl) randomly distributed along a polysaccharide backbone (dextran) in solutions were studied with viscometry and conductometry. This investigation mainly considered the influence of the side‐chain length and the solvent polarity on the polyelectrolyte behavior in salt‐free aqueous solutions. The viscometric data indicated that all the copolymers exhibited polyelectrolyte behavior, and they were plotted in terms of the Rao equation. The viscosity of the polycation with dodecyl as alkyl substituent was also measured in solvent mixtures of water and methanol. The conductometric behavior of these cationic polysaccharides was found to be influenced by the alkyl side‐chain length and the solvent polarity. A nonlinear dependence of the equivalent conductivity on the dielectric constant of the solvent was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009