Ionomer Structure Research Articles

A study of fluorescent-dye polyurethane ionomer

The reaction of toluene diisocyanate with 4-hydroxycoumarin or 7-hydroxycoumarin or dicumarol and other additives to form the structure of fluorescent-dye polyurethane ionomer, which has been successfully synthesized at our laboratary, is demonstrated by Fourier transform infrared spectra. The fluorescence study of coumarins present in N,N-dimethyl acetamide indicates that these coumarins form aggregations and exhibit fluorescence at around 304 nm. The experimental results show that the surface tension of 4-hydroxycoumarin or 7-hydroxycoumarin in N,N-dimethylacetamide appears to decrease with increasing concentration of 4-hydroxycoumarin or 7-hydroxycoumarin. On the other hand, the surface tension of dicumarol in N,N-dimethylacetamide increases with increasing concentration of dicumarol, indicating that increased hydrophilic groups of dicumarol adsorbed at the surface of N,N-dimethylacetamide become even more ordered. For fluorescent-dye polyurethane ionomer in aqueous solution, the number average particle sizes are seen to increase with an increase of coumarin concentration. Since the intermolecular interaction between hydrophilic groups of fluorescent-dye polyurethane ionomer molecules themselves may become strong, therefore, the free volume of these ionomer molecules are considered to be increased significantly. This may be why the number average particle size becomes large. For self-cured films made by fluorescent-dye polyurethane ionomer, the tensile strength is seen to increase with increasing concentration of coumarin, as a result of increased crosslinking resulting from increased hydrophilic groups of coumarins attached to the backbone of the ionomer molecules. The elongation of self-cured film made by dicumarol-based polyurethane iomomer, on the other hand, decreases with increasing concentration of dicumarol. Copyright © 2000 John Wiley & Sons, Ltd.

Gas transport and structural features of sulfonated poly(phenylene oxide)

The effect of ionomer structure on gas transport properties of membranes was investigated. For this purpose physical and transport properties of poly(phenylene oxide) (PPO) and its sulfonated derivative (SPPO) were compared. SPPO has a more rigid structure and a lower free volume, which determines low gas permeability and high permselectivity. Gas transport properties of two types of SPPO—PPO composite membranes with top layers prepared from solutions in methanol or N,N-dimethylacet-amide (DMA) were investigated. The use of SPPO solution in DMA leads to the formation of membranes with higher gas permeability. It was shown that DMA is a morphologically active solvent for SPPO. Strong complexes of SPPO with DMA are formed in solution and retained upon transition into the condensed state. The plasticizing effect of DMA on SPPO determines the high gas permeability of the membranes and is in agreement with their mechanical properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1439–1443, 1997

Gas transport and structural features of sulfonated poly(phenylene oxide)

The effect of ionomer structure on gas transport properties of membranes was investigated. For this purpose physical and transport properties of poly(phenylene oxide) (PPO) and its sulfonated derivative (SPPO) were compared. SPPO has a more rigid structure and a lower free volume, which determines low gas permeability and high permselectivity. Gas transport properties of two types of SPPO—PPO composite membranes with top layers prepared from solutions in methanol or N,N-dimethylacet-amide (DMA) were investigated. The use of SPPO solution in DMA leads to the formation of membranes with higher gas permeability. It was shown that DMA is a morphologically active solvent for SPPO. Strong complexes of SPPO with DMA are formed in solution and retained upon transition into the condensed state. The plasticizing effect of DMA on SPPO determines the high gas permeability of the membranes and is in agreement with their mechanical properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1439–1443, 1997

Domain structure and dynamic heterogeneities of a polyethylene acid ionomer by two‐dimensional solid‐state NMR

AbstractTwo‐dimensional wideline separation (WISE) NMR spectroscopy was employed to investigate the microscopic domain structure of an ethylene‐containing acid ionomer, poly(ethylene‐co‐methacrylic acid). Crystallinities were determined from deconvolution of the proton dimension lineshapes, and domain sizes were computed from proton spin diffusion behavior. The time‐scale for spin diffusion between the acid groups and the amorphous regions is less than 1 ms, because the methacrylic acid groups are situated in the amorphous domains. On the other hand, communication between amorphous and crystalline domains requires several milliseconds, consistent with crystalline domain sizes of ca 4 nm. The presence of intermolecular hydrogen‐bonded cross‐linking is clearly detected by the broad proton linewidth associated with the rigid methacrylic acid groups. It is shown that imbibed hexadecane, which strongly plasticizes the amorphous regions of the copolymer, has little effect on crystallinity, crystalline domain sizes or cross‐link sites.

Anti Electrostatic Properties of Various Types of Ethylene Ionomers

The relationship between ionomer structure and surface resistivity (ρs) was studied for Na, K, Cs, Mg, and Zn ionomers prepared from poly(ethylene-co-methacrylic acid) (EMAA) and poly(ethylene-co-acrylic acid) (EAA). The study revealed that only ionomers highly neutralized with alkali metal cations exhibit anti-electrostaticity and the origin of ionic conduction was assumed to result from the transfer of water-coordinated metal cations. The method of mixing high- and low-acid ionomers was found to be effective in reducing the magnitude of moisture absorption while maintaining the anti-electrostaticity. Blends of a potassium ionomer with a wide variety of thermoplastics were also prepared to evaluate the possibility of using ethylene ionomers as anti-electrostatic additives. Interestingly, the effect of the potassium ionomer upon ρs of the blends differed by the type of the thermoplastics, suggesting that how the ionomer phase distributes over the blends may be influenced by local interactions between ionomer and polymer matrix phases.