Dependence of chain conformation on degree of sulfonation and counterion dissociation of sodium poly(styrene sulfonate) in semidilute aqueous solution

The chain conformation of sodium poly(styrenesulfonate) (NaPSS) in the semidilute aqueous solution, estimated from the plots of reduced viscosity versus segmental concentration, was found to be dependent on the degree of sulfonation and dissociation extent of counterions. The latter, altered by the content of sodium chloride external salt, was estimated from the ionic conductivity measurements on the basis of the modified Manning's conductivity theories with consideration of the influence of chain overlapping in the semidilute regime. The results indicate that the increase of chain extension of NaPSS with counterion dissociation was further enhanced by increasing the degree of sulfonation.     

Soluble polyelectrolyte complexes composed of poly(ethylene oxide)-block-poly(sodium methacrylate) and poly(methacryloyloxyethyl trimethylammonium chloride)

Complexation between poly(methacryloyloxyethyl trimethylammonium chloride), PMOTAC, and poly(ethylene oxide)-block-poly(sodium methacrylate), PEO-block-PMANa with MANa blocks with two different molecular weights has been investigated by light scattering, LS, viscosimetry and conductivity measurements. Owing to the PEO blocks the polyelectrolyte complexes are water-soluble particles. Effects of the ratio of the oppositely charged monomer units, the ionic strength of the solution, and solution pH have been studied. With the 1:1 mixing ratio stable polyelectrolyte complexes, PECs, with spherical shape were formed. When either the cationic or anionic component was in excess, charged non-stoichiometric complexes were formed. The complexes were stable also in solutions with comparatively high ionic strength, though stronger secondary aggregation was observed. By changing the solution pH the degree of dissociation of PEO-block-PMANa could be adjusted. In the vicinity of the pK_a,average of PMAA, a minimum in the particle size and a maximum in the solution conductivity were observed. In solutions with lower pH, a typical self-complexation of PEO-block-PMAA was detected. Also, unexpected interactions between PMOTAC and the self-complexes of PEO-block-PMAA were observed.     

Interaction of sodium dodecyl sulfate with polyelectrolyte complex from diazoresin and poly(sodium styrene sulfonate) in aqueous solution

Polyelectrolyte complex diazoresin–poly(sodium styrene sulfonate) (DR–PSS) from diazoresin (DR) as cationic polyelctrolyte and poly(sodium styrene sulfonate) (PSS) as anionic polyelectrolyte does not dissolve in water or organic solvent because of its electrostatic crosslinking structure. It was found that the complex dissolves considerably aqueous solution of sodium dodecyl sulfate (SDS) and confirmed that the DR–PSS—SDS system possesses extraordinary thermostability as well as high photosensitivity and can be used directly to produce a photoimaging coating. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1817–1821, 1998     

Investigation of the interpolymer association between poly(vinyl alcohol) and poly(sodium styrene sulfonate) in aqueous solution

A viscosimetric method has been used to study the interpolymer association between poly(vinyl alcohol) (PVA) and poly(sodium styrene sulfonate) (PSSNa) in aqueous solution. At constant molecular weight of PSSNa, it was found that, the PVA and PSSNa associations were improved with the decrease of molecular weight of PVA and the decrease of its hydrolysis degree. The measurement of intrinsic viscosity [η] and the determination of Huggins associative coefficient K_H of different PVA samples were used to select the most appropriate PVA sample, which leads to homogeneous polymer–polymer mixtures (PVA with hydrolysis degree 87–89%, molecular weight 124,000–186,000 g/mol, intrinsic viscosity [η] = 1.02 dL/g, and Huggins associative coefficient K_h.ass = 0.76). The obtained results show that the interpolymer association between PVA and PSSNa, in aqueous solution, is mainly due to intermolecular hydrogen bonds between hydroxyl groups of PVA and sulfonate groups of PSSNa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies of the antenna effect in polymer molecules. 29. Synthesis and properties of poly[sodium styrene sulfonate-co-(4-acryolyloxyphenyl)-10,15,20-tritolylporphyrin] in aqueous solution

The novel water soluble antenna polyelectrolyte: poly[sodium styrene sulfonate-co-(4-acryolyloxyphenyl)-10,15,20-tritolylporphyrin] (PSSS-Po) was synthesised, and its photophysical and photochemical properties were studied. Solubilisation of the various molecular probes such as pyrene or perylene in aqueous solution of the PSSS-Po proved that the polymer chain adopts the compact conformation. The interior of the polymer pseudomicelle is significantly less polar than water. The effective quenching of polymeric porphyrin fluorescence by sulfopropyl viologen (SPV) can be explained considering the possibility of electron transfer from the singlet-excited state of Po to SPV. This has been supported by measuring an absorption spectrum for PSSS-Po/SPV system after selective irradiation of Po chromophores. The formation of the new absorption bands characteristic for SPV⁻ radical anion indicated that the charge separation was achieved in that system.     

以低分子量聚乙烯基苯磺酸钠为模板的聚3,4-二氧乙烯噻吩水分散体的制备及性能

通过RAFT聚合,制备了低分子量的聚乙烯基苯磺酸钠（PSS）;其次以低分子量的聚乙烯基苯磺酸钠为模板制备了聚3,4-二氧乙烯噻吩（PEDOT）：聚乙烯基苯磺酸钠（PSS）水分散体,研究了作为模板的聚乙烯基苯磺酸钠的不同分子量对PEDOT：PSS水分散体结构和性能的影响。结果显示：通过核磁氢谱（¹H NMR）表征,证明成功制备了分子量为3900,4900,9600和18300的聚乙烯基苯磺酸钠。用荧光探针法发现低分子量PSS在水中能形成胶束,临界胶束浓度在10^-6g·ml^-1左右。用四探针表面电阻测试发现,低分子量PSS为模板可明显提高PEDOT薄膜的导电性,最大提高了近3倍。用紫外可见分光光度计（UV）研究发现,以低分子量PSS为模板使PEDOT的透明性有一定的下降,这主要是由于RAFT试剂部分和PEDOT：PSS的相分离造成的。热稳定性的测试表明,低分子量PSS为模板对PEDOT的热稳定性没有明显的影响。     

Differences in association behavior of isotactic and atactic poly(methacrylic acid)

In this paper we show by light scattering techniques that polymer tacticity introduces an opposite association behavior in the case of aqueous solution of poly(methacrylic acid) in the presence of 0.1 M NaCl. Aggregates of highly stereoregular isotactic poly(methacrylic acid), iPMA, are disrupted by shear and gradually reform in solution at rest, whereas those of the usual atactic form, aPMA, multiply as a result of mechanical stress (phenomenon of negative thixotropy) and gradually decrease in number after its cessation. The aggregates have characteristics of microgel particles and may act as precursors for temperature induced gelation at higher concentrations. According to the shape parameter ρ (∼0.6 and ∼0.70 for iPMA and aPMA, respectively) iPMA aggregates have a denser core than aPMA ones. Additional differences between both isomers are demonstrated at higher degrees of neutralization, α_N, through the analysis of the polyelectrolyte slow mode, which was identified for all α_N > 0.25 with iPMA but only for α_N = 1 with aPMA.     

Polyelectrolyte complexes IV. Interpolyelectrolyte complexes between some polycations with N,N-dimethyl-2-hydroxypropyleneammonium chloride units and poly(sodium styrenesulfonate) in dilute aqueous solution

We report first on the interpolyelectrolyte complex formation (PEC) between one polycation of integral type having about 95 mol% of N,N-dimethyl-2-hydroxypropyleneammonium chloride units in the backbone (PCA₅) and poly(sodium styrenesulfonate) (NaPSS), in dependence on the polyion concentrations and the mixing order. The PEC formation was qualitatively followed by viscometry, conductometry and UV-spectroscopy. Quasi-soluble PECs could be formed in the polyion concentration range of 0.1-1.0 unit mM. A complex stoichiometry close to 1:1 was found by both the qualitative measurements on the formation of quasi-soluble PEC in dilute aqueous solutions (when PCA₅ concentration was lower than the overlap concentration, C<C^∗) and elemental analyses of the insoluble PEC formed at the high polycation concentration (50 unit mM, C?C^∗). The influence of the ionic strength on the PECs stability was followed by the subsequent addition of NaCl up to an ionic strength of 3.5 M on the reaction mixture, after the PECs formation with three polycations different by both the content of quaternary ammonium salt groups in the backbone and the degree of branching (PCA₅, PCA₂₀ and PCT₂₀). No dissociation of PECs into the original components was evidenced irrespective of the polycation structure and the mixing order.     

Graft copolymerization of poly(vinyl chloride) with styrene. II. Thermal behavior

Thermal behavior of graft copolymers of polyvinyl chloride with polystyrene prepared by using a cationic initiator (AlCl₃) was evaluated by measurement of rates of dehydrochlorination in nitrogen atmosphere. With increase in the extent of grafting the rates were found to decrease. Dynamic thermogravimetric analysis revealed an overall improvement in thermal stability of copolymers. Development of polyene sequences in degraded polymer samples was evaluated by measurement of electronic absorption spectra. In comparison to PVC, graft copolymer samples had fewer conjugated double bonds.     

Light scattering and viscoelasticity study of poly(vinyl alcohol)-borax aqueous solutions and gels

Poly(vinyl alcohol)-borate (PVA-borate) aqueous solutions properties with PVA concentrations ranging from 2 to 60 g/L and borax concentrations of 0.0 and 0.2 M were investigated at room temperature using static and dynamic light scattering (SLS and DLS), and dynamic viscoelasticity measurements. Light scattering and viscoelasticity data revealed that all the PVA-borate aqueous systems, except those with [PVA]≥40 g/L and [borax]=0.2 M, behaved as solutions. For PVA-borate aqueous systems with [PVA]≥40 g/L and [borax]=0.2 M, light scattering data revealed that these systems behaved like gels, but viscoelasticity data showed that these systems were in flow states. The experimental data suggest that PVA-borate aqueous systems with [PVA]≥40 g/L and [borax]=0.2 M are thermoreversible gels with finite equilibrium life time of thermoreversible borate-PVA di-diol crosslinks. The thermoreversible crosslinks can be observed by the non-perturbing light scattering technique but not by the pertubing rheometric method. These results indicate the advantage of light scattering relative to rheometers for studying the physical or reversible crosslink gels.     

Adsorption of poly (4‐sodium styrene sulfonate) on kaolinite clays

The adsorption of polymer on clay particles has great importance in many industrial applications. This work aimed to study the adsorption of anionic polymer, poly (4‐sodium styrene sulfonate), on kaolinite clay surfaces. Three different Egyptian kaolinite clay samples were used. The kaolinite clays were saturated with sodium or calcium cation. It was found that the Freundlich isotherm is applicable for this polymer adsorption on kaolinite. The parameters of the Freundlich equation are very close, indicating a comparable nature for the binding behavior between the different samples of kaolinite and the adsorbed polymer. The adsorption process was examined at different pH values (3, 6, and 9 ± 0.1) to cover the range below and above the point of zero charge of kaolinite surfaces. It was found that, below this point, the polymer adsorption increased, while above it the polymer adsorption decreased. The polymer adsorption on calcium kaolinite was higher than that of sodium kaolinite at the same pH value. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1712–1719, 2006     

Structure of poly(vinyl pyrrolidone) - C70 complexes in aqueous solutions

Aqueous solutions of poly(vinyl pyrrolidone)-fullerene complexes, PVP/C₇₀, have been studied using static and dynamic light scattering. Two diffusive processes were observed. The slow diffusion describes the motion of large PVP/C₇₀ clusters, whereas the fast diffusion is associated with the presence of single PVP molecules or small individual PVP/C₇₀ complexes of the order of a single PVP chain. The molar mass and the size of the PVP/C₇₀ clusters increase upon increasing the fullerene content. However, when the fullerene content is kept constant, an increase in the molar mass of the matrix PVP does not influence the mass and the size of the clusters. Dilution of the PVP/C₇₀ solutions has no effect on the clusters either. In PVP/C₇₀ there is a specific molar ratio of C₇₀ per repeating units of PVP that is same for all the samples studied.     

Evaporation of aqueous solutions of organic acids through spread films of poly(diallyldimethylammonium chloride)/sodium dodecylsulfate complex

The films with the extreme concentration of poly (diallyldimethylammonium chloride)/sodium dodecylsulfate complex spread to the surface of aqueous solutions of formic and acetic acids reduce the evaporation rate of liquids by 3–6% and demonstrate selective properties increasing water content in the vapor by 1–3 abs.%. The concentrations of solutions were up to 30 vol.%. The formation conditions of such films were determined by means of the Wilhelmy plate technique. Surface tension isotherms of aqueous solutions of acids were also obtained.     

Synthesis, characterization and swelling behaviour of poly(methacrylic acid) brushes synthesized using atom transfer radical polymerization

Poly(methacrylic acid) brushes have been prepared utilizing the “grafting from” technique and a living radical synthesis route using a two stage process. Firstly a poly(1-ethoxyethyl methacrylate) brush was synthesized by atom transfer radical polymerization and then thermally decomposed to poly(methacrylic acid). The swelling behaviour of the weak polyacid brush was investigated as a function of pH and salt concentration in aqueous solutions using atomic force microscopy. Force pulling measurements were used to establish the molecular weight and the grafted chain density. The swelling transition was found to be at pH 9; which is significantly different to the pK_a (5.5) of untethered poly(methacrylic acid). We attribute this large shift in pK_a to the high grafting density of these brushes. This can be explained as a result of the Coulombic repulsion of neighbouring charges. High salt concentrations (0.3 M Na⁺) also collapse the brush layer. Conversely low salt concentrations cause an increase in the thickness of the brush, a behaviour expected for osmotic brushes.     

A structural study of polyelectrolyte gels in a unidirectionally swollen state

We investigated the structures of polyelectrolyte gels, poly(N-isopropylacrylamide-co-2-acrylamido-2-methylpropane sulfonic acid) (NIPA/AMPS) hydrogels in a unidirectionally swollen state by using small-angle X-ray scattering (SAXS). The SAXS results show that the structure of the NIPA/AMPS gels strongly depends upon the composition of NIPA/AMPS. Increase in composition of AMPS causes suppression of concentration fluctuations in the long wavelength. As a consequence, a NIPA/AMPS hydrogel with a low composition of AMPS macroscopically phase-separated at high temperatures, while microphase separation occurred for a NIPA/AMPS gel with a higher composition of AMPS. The instability in the microphase separation initially occurred in the direction perpendicular to the swelling for the latter gel. In the disordered state near the microphase separation region, an elliptic scattering pattern was observed, and the scattering intensity around the peak position in the direction perpendicular to the unidirectionally swelling was larger than that in the direction parallel to it. The behavior became more remarkable, as the interaction parameter χ became larger. These behaviors are consistent with the prediction from the Rabin-Panukov theory. The scattering vector at the scattering maximum in the perpendicular direction q_m,⊥ significantly shifted to smaller q, where q represents the magnitude of the scattering vector, when the microphase separation occurred. It is shown that the periodicity of the microphase-separated structure ranged from 300 to 400 Å.     

Foam inhibition in an aqueous sodium dodecylbenzene sulfonate solution by poly(dimethylaminoethyl methacrylate)

The mechanism of foam inhibition in an aqueous sodium dodecylbenzene sulfonate (DBSNa) solution by temperature-sensitive, water-soluble poly(dimethylaminoethyl methacrylate) (PDM) was investigated. The solution's foam collapsing rate, % transmittance, surface tension, pH, temperature, and degree of hydrophobicity of PDM showed that aging a PDM–DBS solution 125 to 280 hr produced a turbid solution and effectively inhibited foaming. Likewise, controlling the pH at 4 ≤ pH ≤ 7 and increasing the hydrophobicity of PDM enhanced the foam-inhibiting action of the polymer. The reaction between DBSNa and PDM was temperature dependent and the temperature effect was almost reversible. When compared with other available commercial antifoaming agents, PDM was found most effective in suppressing foam formation in aqueous DBSNa solution.     

The effects of solution properties and polyelectrolyte on electrospinning of ultrafine poly(ethylene oxide) fibers

The effects of solution properties and polyelectrolyte on the electrospinning of poly(ethylene oxide) (PEO) solutions were investigated. Ultrafine PEO fibers without beads were electrospun from 3, 4, 7 and 7 wt% PEO solutions in chloroform, ethanol, (dimethylformamide) DMF and water, respectively. At these concentrations, the values of [η]C were ∼10 for all solutions. The average diameters of PEO fibers were ranged from 0.36 to 1.96 μm. The higher the dielectric constant of solvent was, the thinner PEO fiber was. The average diameters of electrospun PEO fibers from PEO/water solutions were decreased and their distributions were narrowed by adding 0.1 wt% poly(allylamine hydrochloride) (PAH) and poly(acrylic acid sodium salt) (PAA) due to the increased charge density in solutions. The addition of PAH and PAA lowered the minimum concentration for electrospinning of a PEO/water solution to 6 wt%.     

A facile route to end-functionalized poly(N-isopropylacrylamide) brushes synthesized by surface-initiated SET-LRP

In this study, the facile synthesis of well defined, end-functionalized poly(N-isopropylacrylamide) [poly(NIPAM)] brushes was achieved by surface-initiated single-electron transfer living radical polymerization (SET-LRP). Surface-initiated SET-LRP of N-isopropylacrylamide in the presence of cysteamine chain transfer agent was conducted via Cu(0) generated in situ by the disproportionation of Cu(I) to Cu(0) and Cu(II) in N,N-dimethylformamide at 90 °C. Initially, silicon surfaces were modified with 2-bromopropionyl bromide (2-BPB). [Poly(NIPAM)] brushes with amine end-group were then synthesized via surface-initiated SET-LRP from the immobilized 2-BPB. Various characterization techniques including ellipsometry, grazing angle-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy and water contact-angle measurements were used to characterize the immobilization of 2-BPB on the silicon wafer and the subsequent polymer with amine end-group formation. The addition of free 2-BPB initiator was required for the formation of free polymer chains in solution. The free polymer chains were isolated and used to estimate the molecular weights and polydispersity index of chains attached to the surface. Although there are several chemicals methods for post-polymerization transformation of the halide chain end to amine groups, this study mainly provides a method for in situ functionalization of poly(NIPAM) brushes.     

Interpolymer specific interaction in blends of poly(styrene-co-alkyl acrylate-co-4-vinylpyridine) and poly(styrene-co-alkyl acrylate-co-acrylic acid)

The interpolymer specific interaction of proton donating polymer (PDP) and proton accepting polymer (PAP) in toluene was studied by viscometry coupled with light scattering. The viscometric experiment results show that the stronger the interpolymer interaction is, the higher the viscosity of PDP/PAP blend solution than the weight-average of both components at high concentration, in contrast to lower viscosity at low concentration. Based on the relationship of viscosity enhancement factor with polymer level in solution, a new polymer-polymer interaction parameter k_a to estimate interpolymer interaction was developed. The effects of functional groups content and acrylate unit on interpolymer interaction were studied with this parameter combined with light scattering. The results show that interpolymer interaction ability increases with the functional group and long chain alkyl acrylate content. With the increase in side chain length of acrylate unit, enhancement in the interpolymer specific interaction can be realized.