Polymers and Interfaces

Polymers are materials made of quite monstrous molecules (macromolecules), consisting in many cases of a repeated, simple unit (see Chap. 7). For example, polyacrylamide (PAM) can be written 

As the amide group has a strong affinity for water, it is no surprise that polyacrylamide should by water-soluble, like many other amide-type polymers. Likewise, the polyethers and polyalcohols are generally water-soluble, but for most other functional groups, we could only hope for solubility in an organic medium. However, when a polymer carries acidic or basic groups, it is not only 

Such polymers occur as polysalts and are often strongly dissociated and highly asymmetric. In the case of polyacrylic acid, all the negative charges are carried on the macromolecular backbone which is surrounded by little sodium ions. The opposite situation occurs in polyvinylamine, where the chain carries positive charges. 

In a semi-dilute solution, each macromolecule can be described by a series of unperturbed sections, separated by regions tangled with other chains. This has been schematised in Fig. 3.10, in which the chains mark out a 3-dimensional lattice the nodes of the lattice represent points where the chains tangle. The lattice fluctuates in space and time and the mean mesh size clearly depends on the polymer concentration Cp. In fact. 

SO that decreases as the concentration goes up. Considering any given point of a chain in semi-dilute solution, is a measure of the mean distance to an obstacle (i.e., another chain). 

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Angle-resolved UPS studies of polymers and interfaces Although few polymer systems exist in the form of single crystals, it can be expected that in the future, polymer systems will be prepared which are more ordered. The studies reviewed here are prototypical of what can be done on ordered polymer systems, and lay the basis for future work on ordered systems using photoelectron spectroscopies. 

J. T. Dickinson and A. S. Crasto, Fracto-emission accompanying the deformation and failure of crosslinked polymers and interfaces, in Cross-linked Polymers Chemistry, Properties and Applications (R. A. Dickie, S. S. Labana, and R. S. Bauer, eds.), pp. 145-168, ACS Symposium Series 367, American Chemical Society, Washington, D.C. (1988). 

Electronic and Chemical Structure of Conjugated Polymers and interfaces as Studied by Photoelectron Spectroscopy... 

MODULATED DIFFERENTIAL SCANNING CALORIMETRY 6. THERMAL CHARACTERISATION OF MULTICOMPONENT POLYMERS AND INTERFACES... 

The described methods are meanwhile applied to a multitude of different biological systems. For the following examples, we focus on applications of single-molecule methods to synthetic polymer and interface science. To our knowledge, there is no such application with MT and OT published yet, therefore, we give recent examples on the best studied biopolymer (DNA) for these two methods. 

H. Yu, in Physics of Polymer Surfaces and Interfaces, I. Sanchez ed., Butterworth-Heinemann, 1992, Chapter 12. 

Proteins often have the same high-affinity isotherms as do synthetic polymers and are also slow to equilibrate, due to many contacts with the surface. Proteins, however, have the additional complication that they can partially or completely unfold at the solid-liquid interface to expose their hydrophobic core units to a hydrophobic surface... 

Many complex systems have been spread on liquid interfaces for a variety of reasons. We begin this chapter with a discussion of the behavior of synthetic polymers at the liquid-air interface. Most of these systems are linear macromolecules however, rigid-rod polymers and more complex structures are of interest for potential optoelectronic applications. Biological macromolecules are spread at the liquid-vapor interface to fabricate sensors and other biomedical devices. In addition, the study of proteins at the air-water interface yields important information on enzymatic recognition, and membrane protein behavior. We touch on other biological systems, namely, phospholipids and cholesterol monolayers. These systems are so widely and routinely studied these days that they were also mentioned in some detail in Chapter IV. The closely related matter of bilayers and vesicles is also briefly addressed. 

Lamellar morphology variables in semicrystalline polymers can be estimated from the correlation and interface distribution fiinctions using a two-phase model. The analysis of a correlation function by the two-phase model has been demonstrated in detail before [30,11] The thicknesses of the two constituent phases (crystal and amorphous) can be extracted by several approaches described by Strobl and Schneider [32]. For example, one approach is based on the following relationship ... 

Fleer G J, Cohen Stuart M A, Seheut]ens J M H M, Cosgrove T and Vineent B 1993 Polymers at Interfaces (London Chapman and Hall)... 

Vrij A 1976 Polymers at interfaces and the interactions in colloidal dispersions Pure Appl. Chem. 48 471-83... 

Chemical appHcations of Mn ssbauer spectroscopy are broad (291—293) determination of electron configurations and assignment of oxidation states in stmctural chemistry polymer properties studies of surface chemistry, corrosion, and catalysis and metal-atom bonding in biochemical systems. There are also important appHcations to materials science and metallurgy (294,295) (see Surface and interface analysis). 

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