Chain-packing density

The success of this research is guiding our materials efforts into increasing chain packing density and orientation to increase, including a variety of new thin film deposition techniques. 

Petersen et al., Petersen and Voth,i Spohr, Spohr et al., and Walbran and Kornyshev developed EVB-based models to study the effect of con-finemenf in nanometer-sized pores and fhe role of acid-functionalized polymer walls on solvation and transport of protons in PEMs. The calculations by the Voth group revealed an inhibiting effect of sulfonate ions on proton motions. The EVB model by Kornyshev, Spohr, and Walbran was specifically designed to sfudy effecfs on proton mobilify due to charge delocalization within SOg groups, side chain packing density, and fluctuations... 

Bergstroem, M. 1996. Derivation of size distributions of surfactant micelles taking into account shape, composition, and chain packing density uctuatidng.oll. Interface Scil81 208-219. 

The solubility selectivity of a membrane for a specific gas pair could be increased (in principle) by inducing specific interactions between the polymer and the more soluble component of the gas pair. For example, the substitution of certain polar groups in some rubbery polymers has been found to increase their solubility selectivity for CO2 relative to CH4 (Story and Koros, 1991 Koros, 1985). Unfortunately, the increase in the polarity of a polymer also tends to increase its chain packing density, and as a result, decreases the gas diffusivity in membranes made from that polymer. 

The chain packing density is not close packed, but falls in the range where regular kink blocks are observed. Diamines and secondary and tertiary n-alkylamines have also been studied. 

The phase transition between micellar phases of polyethylene oxide-polypropylene oxide-polyethylene oxide) (PEO-PPO-PEO) triblock copolymer in aqueous solution was investigated as a function of temperature using FTIR spectroscopy. As the temperature increases, PO blocks appear to be stretched conformers with strong interchain interactions, and the formation of a hydrophobic core in the micellar phase. The EO chains are found to change to a more disordered structure with low-chain packing density. Both the EO and PO blocks exhibit dehydration during the phase ttansition (78). 

Figure 10. Dependence of serum adsorption on the extent of surface PEG side chain packing density. Z72i g is calculated as described in section 4.2. Values from this work are compared to published data, for which both the areal mass density of proteins and the average PEG spacing (L) are taken from refs 53 and 54. The radii of gyration were ealculated according to eq 1 for PEG, whereas the original value of 0.42 nm was used for the oligo(ethylene glyeol).

The introduction of fluorine in the form of trifluoromethyl groups (-CF3) in polymer lead to great benefits for improving polymer solubility. This is due to the increase of fractional free volume that limits chain packing density and hence increases solubility and process-ability. We have reported several new aromatic diamine monomers containing trifluoromethyl groups for the synthesis of soluble and... 

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