Poly blended with ionic interactions

The apparatus is described and details given of its use with PETP homopolymer, PS/poly(vinyl methyl ether) miscible blend and styrene-styrenesulphonic acid copolymer/ethyl acrylate-4-vinylpyridine copolymer ionomer blend with ionic interactions. Orientation and relaxation curves were obtained for all three samples. It is concluded that the technique is very efficient for obtaining curves with high precision. For these three systems, the relaxation rate increases with temperature. 

Blends were prepared with cellulose or silk as soon as a common solvent was available [63, 69-71]. Recently, ionic liquids were used. The solvent l-ethyl-3-methyl-imidazolium acetate completely dissolves raw crustacean shells allowing to recover high purity chitin powder or films and fibres by direct spinning [72]. Films of poly(e-caprolactone) (PCL) blends with a-chitin and chitosan were produced. They are completely biodegradable and the crystallinity of PCL is suppressed in the blends due to hydrogen bond interaction between PCL and polysaccharides [73]. Blends were also realized with poly (3-hydroxybutyric acid) (PHB) and chitin or chitosan. They show faster biodegradation than the pure-state component polymers [74,75]. 

For systems of rigid poly diacetylenes with functional or ionic side groups and car-boxylated or sulfonated polystyrene or sulfonated polyester-urea urethanes, molecular composites could be achieved by ionic interactions [51]. The blends exhibited no microphase separation and the miscibility on a molecular length scale was proven by infrared spectroscopic, dynamic mechanical and differential scanning calorimetry analysis. The molecular reinforcement amounted to up to 1 order of magnitude in compliance with a Halpin Tsai description and was achieved by only a few weight percent of the rigid compound. 

Attractive blends for PEMs with high proton conductivity have been made from sulfonated PES, PSU, polyetherketone (PEK), PEEK or poly(2,6-dimethyl 1,4-phenylene ether) (PPE) blended with polybenzimidazole (PBI) or polyetherimide (PEI). To preserve the desired PEM performance, the blends are often crosslinked by radiation, chemical reaction of ionic interactions. For long-term PEM applications it is important that membranes resistance to mechanical, chemical and thermal degradation is maximized. Accelerated aging tests should follow several membrane functionalities, for example conductivity, membrane integrity and permeability. The tests should also identify a possible cross-correlation of effects, namely stress on thermal and/or chemical degradation. 

These 2D spectra can also provide detailed structural information about the solution structure of polymers. Figure 3.26 shows the 2D NOESY spectra of a 50 50 mixture of poly(vinyl chloride) and poly(methyl methacrylate) at 38 wt% concentration [29], a polymer pair reported to form a compatible blend in films cast from tetrahydrofuran (THF). Most polymer mixtures do not form such miscible blends because of the unfavourable entropy associated with molecular-level mixing, and for those pairs that do form compatible blends there is usually some specific interaction (ionic, hydrogen bonding, etc.) between the groups on the different chains [30]. From examination of the chemical structure of the two polymers, however, it is not obvious which interchain interactions lead to the formation of a compatible blend. It has been suggested that hydrogen-bond formation between the poly(methyl methacrylate) carbonyl and the poly(vinyl chloride) electron-deficient methine proton is responsible for this interaction [31]. The top spectrum shows several intra-... 

The interaction forces between the acidic and basic blend component include electrostatic and hydrogen bridge interaction. The sulfonated poly(ethersulfones) and poly(etherketones) were combined both with commercially available basic polymers (e.g., polybenzimidazole Celazole (Celanese), poly(4-vinylpyridine), polyCethylene imine)), and with self-developed basic polymers derived from poly(ethersulfones) [47] and poly(etherketones), including polymers that carry both sulfonic and basic groups onto the same backbone [48]. A wide variety of acid-base blend membranes with a broad property range were obtained. The most important characterization results of the ionically cross-linked ionomer membranes are... 

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