Propylene oxide morphology

Naoi and co-workers [55], with a QCM, studied lithium deposition and dissolution processes in the presence of polymer surfactants in an attempt to obtain the uniform current distribution at the electrode surface and hence smooth surface morphology of the deposited lithium. The polymer surfactants they used were polyethyleneglycol dimethyl ether (molecular weight 446), or a copolymer of dimethylsilicone (ca. 25 wt%) and propylene oxide (ca. 75 wt%) (molecular weight 3000) in LiC104-EC/DMC (3 2, v/v). 

Figure 10.6 Effects of hydroxypropylation on the granule morphology of potato starches, (a) Potato starch granules after hydroxypropylation (at 10% propylene oxide concentration), (b) Effect of increased concentration of propylene oxide (15%) on the starch granule structure (source Kaur et al., 2004).

The stereoregularity—i.e., distribution of the stereosequence length in these polymers—has a marked effect on the crystallization rates and the morphology of the crystalline aggregates. These differences, in turn, influence the dynamic mechanical properties and the temperature dependence of the dynamic mechanical properties. In order to interpret any differences in the dynamic mechanical properties of polymers and copolymers of propylene oxide made with different catalysts, it was interesting to study the differences in the stereosequence length in the propylene oxide polymers made with a few representative catalysts. 

FrOlich et al. [ 140] investigated a system in which DGEBA was mixed with hydroxy-terminated poly(propylene oxide-block-ethylene oxide) as the rubber, with the nanoclay being a synthetic fluorohectorite treated with bis (2-hydroxyethyl) methyl tallow alkylammonium ions. The clay was first blended with rubber, before being dispersed into the reactive epoxy mixture. Modification of the rubber allowed variation in miscibility and differing morphologies and properties. If the rubber was miscible, the intercalated clay led to improved toughness. If the rubber is sufficiently modified, such as with... 

Because of the pendent methyl groups on the propylene oxide side chains, hydroxypropylcellulose is much more lipophilic than HEC. This allows HPC to dissolve in and thicken many organic systems such as ethyl alcohol, aqueous ethyl alcohol, and propylene glycol. Hydroxypropylcellulose is also thermoplastic it can be melt-processed as films, fibers, and structural components. The methyl groups on HPC can create hydrophobic domains, which help explain why highly concentrated solutions of HPC exhibit liquid crystalline morphology (151). 

In a rod-coil block copolymer with poly(propylene oxide) as the coil segment and a slightly elongated rod segment (4Cbiphenylcarboxy-4 -biphenyl-4-n-propyloxybenzoate) the already mentioned honeycomb morphology (see Figure 49) was found as well [168]. 

Another unique approach toward low 6 is to disperse fine foams in PI films, since the e of air is unity. This technique developed by Hedrick et al. [208] typically involves the preparation of PS-PAA-PS (PS polystyrene) triblock copolymer, imidization, and finally higher temperature annealing where thermally labile PS block undergoes thermolysis (depolymerization) to form submicron pores. They utilized a variety of other thermally unstable block such as poly(a-methylstyrene), poly(propylene oxide), PMMA, poly(e-caprolactone), and aliphatic polyesters and examined the effects of chemical structure, fraction, and molecular weight of the block on the resultant morphology (pore size, shape, porosity) and dielectric and thermal, and mechanical properties. In this case, the resulting porous structure depends on the initial microphase separation domain structure of the thermally labile triblock. For example, nano-foamed PI (19% porosity) prepared from triblock consisting of PMDA-3F [3F = l,l-bis(4-amino-phenyl)-l-phenyl-2,2,2-trifluoroethane] (see Fig. 62 for its structure) and poly(propylene oxide) showed a considerably lower e = 2.3) than that of the non-porous homo PMDA-3F e = 2.9) [209]. 

Amphiphilic block copolymers in selective solvents undergo self-assembly into various nanosized morphologies [2,3]. Typical aggregates formed by the block copolymers are polymeric micelles with spherical shapes consisting of a core and a coronal shell. These spherical polymeric micelles are several tens of nanometers across with a narrow size distribution, and they are characterized by their unique core-shell structure, in which a core composed of insoluble blocks is surrounded by a palisade of soluble (hydrophihc) blocks. So far, polymeric micelles intended for biomedical use have been prepared from a variety of amphiphilic block copolymers including PEO-fc-PBLA [51-56], poly(ethylene oxide)-fc-poly(propylene oxide)-fc-poly(ethylene oxide) (PEO-fo-PPO-fo-PEO) (Pluronic) [9], PEO-fo-phosphatidylethanolamine (PEO-fo-PE) [12,13], PEO-fo-PDLLA [40-43], PEO-fc-poly(e-caprolactone) (PEO-fc-PCL) [11], and PEO-fo-poly(lactide-co-glycolic acid) (PEO-fc-PLGA) [57]. 

The morphology of lithium deposits from 1-3 M LiC10.,-EC/PC-ethylene oxide (EO)/ propylene oxide (PO) copolymer electrolytes was investigated." It... 

The effect of stereosequence distribution on crystallization kinetics Is dramatic. We have previously reported our studies on the Important effects of stereosequence length on crystallization kinetics and morphology of propylene oxide polymers (22). Here we summarize the main conclusions of this study, so that results on the time-temperature dependence of mechanical response may be fully appreciated In the light of these conclusions. 

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