Mixed conducting block copolymers

Another type of stereo complex, i.e., a tightly wound 3/1-helix, is formed when polymers of L-lactic acid (PLLA) and D-lactic acid (PDLA) are mixed in the blend.247-248 Also in solution aggregation of block copolymers containing PLA segments has been found 249-250 however, no studies toward the morphology of the aggregates have been conducted. 

Mixed Conducting Block Copolymers and Polyblend Ionic Conductors Preparation and... 

The work carried out in our laboratory has led to the development of synthetic methods required for the preparation of MIEC block copolymers. It will now be necessary to obtain a clear understanding of the structure-microstructure-function interrelationship of the MIEC block copolymers. MIEC block copolymers of controlled structures may be ideal for testing the different hypotheses of coupling between the electronic and the ionic species in mixed conductors [56]. Methods are available to determine the diffusion constants of the ionic species in mixed conducting systems [65]. The diffusion constants of ionic species in mixed con-... 

Common polymers used for blending with PEO include PMMA, polystyrene, poly(vinyl alcohol), poly(vinyl acetate), PPO, poly(2-vinyl pyridine), polyacrylamide (PAAM), styrene-butene block copolymer, and polyacrylate. In these blending systems, LiC104 can form complexes with PEO, attaining ionic conductivities of up to 10 S/cm at room temperature, such as obtained by the blend of PEO with the so-called Flemion polymer, which also shows good mechanical performance. The blend of PEO with a modified natural rubber, which has a low Tg, can attain an ionic conductivity of 10 -10 S/cm. The ionic conductivity of an amorphous array obtained by mixing polyure-thane/siloxane with PEO is also greatly improved. 

The low conductivity of the sulfonated aromatic PEMs at low RH has been attributed to the fact that sulfonated aromatic polymers have fewer connected water domains as well as more phase mixing of the hydrophobic and hydrophilic domains [33], Block copolymers, consisting of covalently bonded chemically dissimilar sequences, exhibit highly periodic microphase-separated structures [34], The characteristic lengths of the structures are determined by the molecular size and are in the 10-100 nm range. Therefore, many research studies have focused on the development of sulfonated multiblock copoly(ether sulfone)s for improving the nanophase-separated structures and proton conductivity under a low RH. 

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