Itaconic anhydride, a biosourced molecule, was readily transformed to polymerizable nonionic amphiphiles of the type R-Ita-R′; these amphiphiles carry an exo-chain double bond, which upon polymerization yielded amphiphilic doublebrush polymers, especially when R and R′ are immiscible, and consequently exhibit a tendency to self-segregate. DSC, WAXS, SAXS, and variable temperature FT-IR studies of these amphiphilic double-brush polymers confirm the occurrence of self-segregation followed by crystallization of the cetyl segments; in most cases a lamellar morphology is seen wherein the two immiscible segments form the alternating lamellae and the polymer backbone presumably lie along their interface. C16-Ita-HEG, which carries a hydrophobic cetyl chain and a hydrophilic heptaethylene glycol monomethyl ether unit, forms a hydrogel upon polymerization at concentrations above 2.5 wt %; an interesting feature of this hydrogel is that it exhibits a reversible thermal and shear-induced transformation to a sol, a property that could be of interest for biomedical applications.

We studied the effect of salt addition on a diblock copolymer system with a negative Flory-Huggins interaction parameter, χ, indicative of attractive interactions between the two blocks. The system studied is poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-PMMA) with added lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. We studied two asymmetric block copolymers, PEO-PMMA(10-33) and PEO-PMMA(10-64), where the numbers refer to the molar masses of the blocks in kg mol -1 . The small angle X-ray scattering (SAXS) profiles for PEO-PMMA(10-33) were featureless at all salt concentrations. In contrast, PEO-PMMA(10-64) exhibited SAXS peaks when the salt concentration was between 0.22 ≤ m (mol Li/kg polymer) ≤ 0.44. The appearance of SAXS peaks only in PEO-PMMA(10-64) is consistent with the predictions of ionic self-consistent field theory developed by de la Cruz and coworkers, which predicts that in systems with negative χ, ordered phases are only found when the volume fraction of the ionic block is about 10%.

We study the phase behavior of a triblock organic-inorganic hybrid copolymer, poly(polyhedral oligomeric silsesquioxane)-b-poly(ethylene oxide)-bpoly(polyhedral oligomeric silsesquioxane) (POSS-PEO-POSS)/ lithium bis(trifluoromethanesulfonyl) imide salt mixture as a function of temperature. The polymer exhibits a lamellar morphology, both in the neat state as well as in the presence of salt. However, the average grain size increases substantially when the electrolyte is heated above 113 o C. The grain structure of this sample changes reversibly with temperature, i.e., smaller grains reappear when the electrolyte is cooled below 113 o C. While annealing block copolymers at high temperatures often leads to an increase in grain size, this change is generally irreversible. The reason for the reversible change in the grain structure of the POSS-PEO-POSS/LiTFSI electrolyte is discussed. The ionic conductivity of the electrolyte also exhibits reversible changes in this temperature window. Knowledge of the grain structure is crucial for understanding ion transport in nanostructured electrolytes.

The limiting current density of a conventional polymer electrolyte (PS-PEO/LiTFSI) and a single-ion-conducting polymer electrolyte (PSLiTFSI-PEO) was measured using a new approach based on the fitted slopes of the potential obtained from lithium-polymer-lithium symmetric cells at a constant current density. The results of this method were consistent with those of an alternative framework for identifying the limiting current density taken from the literature. We found the limiting current density of the conventional electrolyte is inversely proportional to electrolyte thickness as expected from theory. The limiting current density of the single-ion-conducting electrolyte was found to be independent of thickness. There are no theories that address the dependence of the limiting current density on thickness for single-ion-conducting electrolytes.