Sulfonated polyisobutylene telechelic ionomers. XIV. Viscoelastic behavior of concentrated solutions in nonpolar solvents

The effect of molecular variables upon the dynamic viscoelastic behavior of solutions of sulfonated polyisobutylene telechelic ionomers in nonpolar solvents has been investigated. Intermolecular association of the ionic end groups in nonpolar media results in the formation of a transient ionic network which displays a viscous response at low frequencies and an elastic response at high frequencies. The frequency of the transition from viscous behavior to elastic behavior, as well as the plateau storage modulus, is dependent upon molecular variables such as architecture, molecular weight, neutralizing cation, and extent of neutralization. Variables which affect the strength of the ionic interactions, such as temperature and the type of solvent, also influence the viscoelastic response. Solutions of ionomers neutralized with cations of Groups IA and IIA, such as potassium and calcium, behave elastically over most of the experimentally accessible frequency range, while those neutralized with transition metals, such as zinc, display viscous flow over a rather wide range at low frequencies. As in previous studies of dilute solution viscosity behavior, the threearm star trifunctional species was found to form a more extensive network in nonpolar solvents than the linear difunctional species at equivalent concentrations. The failure of time–temperature superposition indicates that these solutions are thermoheologically complex.     

Solution behavior of ionomers. III. Sulfo-EPDM-modified hydrocarbon solutions

The solution viscosity of polymer thickened hydrocarbons normally decreases markedly as temperature is increased. It has been observed that metal sulfonate ionomers, such as sulfonated ethylene propylene terpolymer, or sulfo-EPDM, when dissolved in a mixed solvent behave much differently. Specifically, sulfonated ionomers, dissolved in xylene or paraffinic oils with low levels of a polar cosolvent, can provide solutions whose viscosities are either relatively constant or can actually increase with increasing temperature. This isoviscosity effect can be manifested over broad temperature ranges and is mechanistically different from the behavior of conventional polymer solutions. This unusual behavior is explained on the basis of a simple equilibrium involving solvated ion pairs and is shown to be a specific example of a general phenomenon.     

Solution studies of metal sulfonate ionomers IV: Effects of cosolvents

Previous studies have shown that metal sulfonated ionomers display unusual solution behavior. Typically, inomers, such as metal sulfonated EPDM or sulfonated polystyrene, are readily dissolved in mixed solvents, such as hydrocarbons plus alcohols. Such mixed solvents can provide unusual viscosity-temperature behavior due to the strong inter-or intramolecular interactions of the ionic groups. This paper is concerned with studies directed at a variety of polar cosolvents, including amines, alcohols, acids, amides, and esters, in interactions with zinc sulfonated ethylene propylene diene monomer (sulfo-EPDM). Within various classes of compounds the structural effects of such cosolvents on the solution viscosities of sulfonate ionomers have been elucidated. Generally, amines and alcohols have been found to be the most effective cosolvents. Amines appear to form a specific complex with zinc and can virtually eliminate ion pair association at extremely low levels. Within a homologous series, those compounds of shortest hydrocarbon chain length provide the most effective solvation of the ionic groups of sulfonated EPDM. The effect of structure of the amines or alcohols on solution viscosity has shown the efficiency of cosolvent interaction proceeding as normal > iso > secondary > tertiary in the alcohol series. These results are interpreted as a consequence of the cosolvent solvating the ionic groups wherein the more bulky cosolvents are least effective in solvating the metal cations.     

Solution behavior of Na sulfonated polystyrene: Dipole moment determinations

Solution behavior of Na sulfonated polystyrene (NaSPS) ionomers with different percentages of sulfonate was studied by viscosity and dipole moment measurements. Two solvents of different character were chosen, i.e. dioxane (? = 2.22) and dimethyl formamide (DMF, ? = 36) and their mixtures. The reduced viscosity as a function of concentration in polar solvents reflects the ‘polyelectrolyte’ behaviour of the ionomers. Mean-squared dipole moment (<μ²>/x) values were calculated over a temperature range of 20–100°C, in dioxane and in a mixture of 4% DMF in dioxane. The results confirm the ‘polyelectrolyte’ behavior of ionomers by the addition of a small amount of polar cosolvent. The effect of increasing temperature on <μ²>/x in the DMF-dioxane mixture is attributed to the formation of a coordination complex.     

Redox-active liquid-crystalline ionomers: 1. Synthesis and rheology

Liquid-crystalline (LC) copolymers with redox-active groups were prepared by copolymerization of mesogenic and ferrocene-containing monomers (up to 10%). In these copolymers the ferrocene groups can be oxidized reversibly to prepare ionomers, while retaining the LC phase. It is thus possible to vary the amount of ionic groups in the ionomers by a redox reaction. The oxidized (charged) polymers show a strong excess X-ray scattering at small angles. This is typical for ionomers and is assigned to the scattering of ionic aggregates. Dynamic mechanical measurements show that these aggregates are effective as crosslinking points. Thus an oxidation-reduction reaction can be used to transfer an uncrosslinked polymer (reduced ferrocene groups, uncharged) reversibly into an oxidized polymer that acts like a weakly crosslinked gel.     

Dielectric properties of an epoxy resin and its composite II. Solvent effects on dipole relaxation

Dipole relaxation dielectric loss behavior of a fiberglass-epoxy composite has been studied following submersion in polar and nonpolar organic solvents as well as in acidic and basic aqueous solutions. Certain adsorbed organic solvents, such as 1,2-dichloroethane, had little influence on the epoxy relaxation behavior. Other solvents, including chloroform, increased the composite relaxation intensity and shifted the temperature-frequency region over which the relaxation occurred. Both the amount of solvent uptake and the degree of interaction of solvent molecules with epoxy polar functional groups appear to control the amount of relaxation behavior perturbation. Arrhenius activation energies for relaxation were lowered by solvent uptake from the dry composite value of 18 kcal/M to between 6 and 16 kcal/M, depending on the solvent adsorbed. Submersion in methanol and chloroform sharply increased the direct current conductivity of the composite. Two molar acidic and basic solutions had little influence on composite dipole relaxation behavior other than the well known behavior associated with moisture uptake.     

Telechelic ionomeric poly(butylene terephthalate): Synthesis,characterization and comparison with random ionomers

Telechelic poly(butylene terephthalate) (PBT) ionomers have been prepared by melt synthesis using a new polycondensation process that involves a pre-reaction of sulfobenzoic acid sodium salt with butanediol. No side reaction occurs and the incorporation of the ionic groups is quantitative. The addition of a buffer agent, such as Na₃PO₄, to the catalyst reduces the THF formation and improves the polycondensation rate. The comparison of the thermo-mechanical and physical properties between random and telechelic ionomers is also reported. The ionic groups act as chain-extension reversible electrostatic links for telechelic ionomers while act as cross-links in random ionomers. Therefore, random ionomers present a consistently higher melt viscosity compared to telechelic ionomers and to PBT and for this reason high molecular weight random ionomers cannot be obtained by melt polycondensation. Thermal and hydrolytic stabilities of telechelic ionomers are comparable with those of commercial PBT and consistently higher respect to those of random ionomers. The presence of ionic groups decreases the translation mobility of the polymer chains thus lowering the crystallization rate.     

Comparison of Various Solvent Media Efficiency in the Grinding of a Frit Containing Zirconium Oxide

In the present work thermal and chemical properties of a glass-ceramic frit containing zirconium oxide are evaluated after milling in various polar and nonpolar solvents. Particle-size distribution is one of the main variables investigated to evaluate the efficiency of several solvents. Milling in various solvents does not affect the thermal properties of the glass while the presence of polar groups in the solvent molecule increases the cation release from the glass.     

Zum kautschukelastischen verhalten von polyurethan-ionomeren

Dispersions of cationic and anionic ionomers of polyurethanes were prepared by the acetone method. Characteristic changes of the viscosity were observed during the addition of water. This change was studied with a cationic ionomer. The ionomers are mainly associated dimeric species in solution of acetone. During the addition of water the ions are solvated while the hydrophobic segments are increasingly associated. At the maximum of the observed viscosity the apparent molecular weight M_max ≈ 3 M_min. In the absence of solvents the ionomers behave like crosslinked materials even if no covalent crosslinks are present. The modulus at small elongations is a linear function of the square of the concentration of the cations. It is concluded that two ionic centers are required per crosslink. The anionic ionomers were also chemically crosslinked since an excess of isocyanate was used. A linear increase of the modulus was observed with increasing amount of chemical crosslinks, while the concentration of ions and hydrogen bonds was constant. The crosslinks formed by ions can be suspended by swelling with water. The portion of the modulus caused by ionic crosslinking can be computed from the difference of the moduli in the dry and swollen state.     

Behaviour of sulphonated EPDM in multicomponent/multiphase systems

The interactions of polymers containing low levels of ionic groups in selected environments has been a relatively unexplored area. For selected applications, it is important to understand how these polymers interact with a variety of cosolvents and/or solid substrates. The purpose of this study is aimed towards gaining an insight into these interactions. The solution behaviour of various inorganic salts (calcium, magnesium and zinc) of sulphonated ethylene-propylene diene monomers (EPDM) was investigated in order to determine the relative strength of interactions between sulphonate groups, cosolvents of varying structure and substrates possessing a specific chemistry. Viscosity-time-temperature relationships show that the properties of the polymer-cosolvent solutions are controlled to a large extent by ionic forces. The magnitude of these forces is dependent upon the nature of the cation and the specific molecular structure of the cosolvent. The weakest interaction was found to occur between the calcium neutralized polymer and cosolvent, while magnesium and zinc neutralized samples showed progressively stronger interactions. The extent to which these ionic forces can interact with their ‘environment’ depends upon the molecular structure of the cosolvent, in particular the structure of the polar ‘head’ is of paramount importance. These become even more apparent when the polymer and polymer-cosolvent complex is permitted to adsorb onto insoluble, solid substrates possessing a specific surface chemistry (in this instance, metal sulphate substrates). The results show that if the cation on the sulphonated polymer is identical to the cation contained in the metal sulphate, the adsorption of polymer is maximized (i.e., like prefers like). In addition, the nature of the cation is very important in determining the extent and, most probably, the mechanism of adsorption.     

Preparation,characterization, and some properties of ionomers from a sulfonated styrene–butadiene–styrene triblock copolymer without gelation

The conditions for the sulfonation of a highly unsaturated styrene–butadiene–styrene triblock copolymer (SBS) in cyclohexane containing a small amount of acetone with acetyl sulfate made by sulfuric acid and acetic anhydride without gelation were studied. After neutralization with metallic ions, the ionomers were characterized with IR spectrophotometry, dynamic mechanical analysis, and transmission electron microscopy. The melt flow, solution properties, and mechanical properties of the ionomers were studied. The results showed that gelation occurred during the sulfonation of SBS in cyclohexane at a 5–10% concentration without acetone, whereas in the presence of 5–10 vol % acetone, sulfonation proceeded smoothly without gelation. Transmission electron microphotographs of the lead ionomer indicated the presence of ionic domains. A dynamic mechanical spectrum showed the presence of three transition temperatures: ?82.9, 68, and 96.5°C. The melt viscosity of the ionomer increased with the sulfonate content. The melt viscosity of the different ionomers neutralized with different cations seemed to decrease with decreasing ionic potential for both monovalent cations and divalent cations The solution viscosity of the sodium‐sulfonated ionomer increased with increasing sulfonate content. The ionomer still behaved as a thermoplastic elastomer and showed better mechanical properties than the original SBS. The tensile strength of the different ionomers decreased as follows. For the monovalent cations, it decreased with decreasing ionic potentials: Li⁺ > Na⁺ > K⁺. For the divalent cations, it decreased with increasing ionic potentials: Pb²⁺ > Zn²⁺ > Mg²⁺. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1398–1404, 2005     

高分子稀溶液中溶剂对分子特性与流变性能的影响

本文研究了不同溶剂对离子性和非离子性高分子稀溶液的分子构型和流变性能的影响.在部分水解的聚丙烯酰胺水溶液中加入无机盐,测量并计算了分子扩张因数,特征粘度与盐浓度、盐离子价数、溶液pH值的关系.同时使用不同的有机溶剂测量聚丁烯溶液的Maxwell模型松弛时间和分子扩张因数.研究表明,高分子稀溶液可藉调整溶剂性质的方法以达到期望的流变特性.     

1,1-Dimethyl-2,3,4,5-tetraphenylsilole as a Molecular Rotor Probe to Investigate the Microviscosity of Imidazolium Ionic Liquids

Room temperature ionic liquids (ILs) have attracted interest for a wide variety of applications, yet many details regarding their physicochemical properties remain unclear, including how their bulk properties differ from those on the microscopic scale. In this work, 1,1-dimethyl-2,3,4,5-tetraphenylsilole (DMTPS) was employed as a molecular rotor probe to investigate the microviscosities of three imidazolium ILs: butylmethylimidazolium tetrafluoroborate, butylmethylimidazolium hexafluorophosphate, and octylmethylimidazolium tetrafluoroborate. The photoluminescence quantum yields (PL QYs) for DMTPS in these ILs were compared to those measured for the same probe in nonpolar viscous (hexanes–mineral oil) and polar viscous (glycerol–ethanol) solvent systems and the microviscosities calculated using the Förster–Hoffmann equation. The PL QY of DMTPS was found to be higher in ILs than in low viscosity solvents but not as high as in nonpolar solvents of similar bulk viscosity. These results indicate that the microviscosity experienced by the silole in the ILs is less than the measured bulk viscosity, suggesting that the siloles occupy a “domain” within the IL matrix that allows enough free volume for the silole to deactivate rotationally. The stability of DMTPS was also shown to be greater in the ILs than in molecular solvents, suggesting that the IL medium might permit the construction of a robust optoelectronic device.     

Fractionation of Gluten Lipids with Supercritical Carbon Dioxide

Gluten lipids are of two kinds, polar and nonpolar. Both groups consist of a large number of lipids. Gluten lipids can be extracted by conventional solvents as ethanol but also by supercritical carbon dioxide. The high density and the good mass transport properties make the supercritical fluid an excellent solvent. Ethanol extracted gluten lipids have been fractionated with supercritical CO₂ at different pressures and constant temperature. The extract contains triglycerides and free fatty acids, and a more concentrated fraction of polar lipids is left in the extraction vessel. While both polar and nonpolar lipids are soluble in ethanol, only nonpolar lipids are dissolved by supercritical CO₂. An addition of a small amount of ethanol to the CO₂, can, however, increase the solubility of the polar lipids.     

Synthesis of novel amphiphilic pH‐sensitive polyurethane networks through W/O soap‐free emulsion polymerization process. II. Mechanical property and biphasic swelling behaviors

Amphiphilic urethane acrylate anionomer (UAA) chains exhibited very different solution properties in various solvents, such as water, dioxane, and dimethyl sulfoxide (DMSO). UAA chains showed a polyelectrolyte effect in a highly polar solvent, DMSO, but gave constant viscosity at various concentrations in aqueous solution, because of the microstructural difference of the UAA chain formed in solvents. In polar solvents (water and DMSO), the swelling of UAA networks prepared with water and dioxane strongly depended on the properties of the hydrophilic domains. In low and nonpolar solvents (dioxane and methylene chloride), the swelling of UAA networks was only dependent on the property of the hydrophobic segments. In the polar solvent medium, UAAG networks prepared with water exhibited greater swelling than UADG networks prepared with dioxane. Concerning swelling in a nonpolar solvent, however, UADG networks showed greater swelling than UAAG networks. This is because of the microstructural difference between these networks, which was confirmed by the mechanical property measurement. UAAG networks, having highly microphase‐separated structures, had higher modulus and transition temperatures than the UADG networks, because of the microstructural difference between UADG and UAAG networks. Both the UAAG and UADG networks take up two immiscible solvents simultaneously within their hydrophobic and hydrophilic domains. Equilibrium swelling ratio of these networks in two immiscible solvents strongly depends on their hydrophilic/hydrophobic balance that is controlled by the type of solvent used in the network synthesis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 621–630, 2001     

Reactions of conjugated fatty acids. III. Kinetics of the Diels-Alder reaction

Summary The kinetics of a Diels-Alder-type reaction between diethylazodicarboxylate andt,t-9,11-octadecadienoic acid has been studied in various solvent systems and with acidic catalysts. The rate of the reaction was found to vary as follows: a) the reaction rate is faster in polar solvents than in nonpolar solvents; b) addition of acidic catalysts to nonpolar solvents increases the rate of the reaction, and acidic catalysts appear to have no effect on the rate of reaction in polar solvents; c) when compatibility can be maintained, addition of water to polar solvent systems appears to increase the reaction rate in proportion to the amount of water added. The reaction follows second-order or pseudo second-order kinetics. Probably it is more complex than the over-all reaction kinetics indicate. Certain reactions were studied at two temperatures, and information on activation energy of the reaction has been obtained. Presented at fall meeting, American Oil Chemists’ Society, Philadelphia, Pa., Oct. 10–12, 1955.     

The solubility of poly(vinylidene chloride) in solvent mixtures

Effective solvents for poly(vinylidene chloride) (PVDC) were obtained by mixing a polar aprotic solvent with a less polar solvent of cyclic structure. The polar components included sulfoxides, N,N-dialkylamides, and N-alkyl lactams. The cyclic cosolvents included aliphatic and aromatic hydrocarbons, ketones, ethers, and thioethers. The problem of solubility of a crystalline polymer in a mixed solvent was analyzed by extending the Flory theory of melting point depression to three component mixtures. The results predict that favorable mixtures arise when at least one of the components interacts strongly with the polymer but is nearly incompatible with the cosolvent. This is in qualitative agreement with the observed behavior of PVDC.     

Effect of filler geometry on the diffusion and transport behavior of aromatic solvents and commercial oil through nitrile rubber nanocomposites

The diffusion and transport behavior of nitrile rubber nanocomposites was studied with respect to different types of filler and also different types of solvents. The nitrile rubber nanocomposites showed considerable variations in the molecular transport owing to the tortuosity of path, decreased segmental mobility, and difference in particle geometry. As the matrix under consideration is polar, the behavior of the filled systems in aniline was also studied with a view to understand the polar–polar interaction between the filled matrix and the solvent. The oil repellency as a result of filler addition in the matrix was investigated by studying oil uptake of the nanocomposites. In all these investigations, it has been observed that the filler geometry played an important role in controlling the molecular transport through the polymer matrix. The layered silicate‐filled system showed better solvent resistance and hence minimum solvent uptake in polar and nonpolar solvents and better oil repellency followed by titanium dioxide and calcium phosphate filled systems. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Studies on the characterization of phase inversion during emulsification process and the particle sizes of water‐borne microemulsion of poly(phenylene oxide) ionomer

In this article, the lightly sulfonated poly(phenylene oxide) (SPPO) ionomers in a series of mixing solvents were emulsificated by water to form a series of water‐borne microemulsions. The phase inversion during the emulsification process of SPPO ionomer solutions was characterized by measuring the variation of conductivity, viscosity, and surface tension with the addition of water. The effects of properties of solvent systems on the phase inversion procedure, the particle size of emulsions with different solvent systems, and ionic contents of the polymer chain were discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 690–694, 2000     

Anionic ring‐opening polymerization of adipic anhydride initiated by potassium poly(ethylene glycol)ate

Poly(adipic anhydride) (PAA) was prepared by the ring‐opening polymerization of adipic anhydride (AA) initiated by potassium poly(ethylene glycol)ate. The effects of various factors, such as the amount of initiator, concentration of the monomer, reaction time and temperature, and polarity of the solvent on the polymerization were investigated. The crude polymerized product was a mixture of PAA homopolymer and poly(ethylene glycol)–poly(adipic anhydride) block copolymer, as confirmed by ¹H‐NMR and gel permeation chromatography. Chain‐transfer reactions occurred intensively for the AA polymerization in both the nonpolar solvent toluene and the polar solvents CHCl₃ and tetrahydrofuran, which predominantly determined the molecular weight and the monomer conversion for the polymerized product. The lower monomer conversion in toluene was ascribed to a lower livingness for the initiator in the nonpolar solvent when compared with other two, polar solvents. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2194–2201, 2003