Macromolecules, surface properties

T. Matsuda, G. D. Smith, R. G. Winkler, D. Y. Yoon. Stochastic dynamics simulations of n-alkane melts confined between solid surfaces Influence of surface properties and comparison with Schetjens-Fleer theory. Macromolecules 28 65- 13, 1995. 

Emulsion copolymerization of EUP and comonomers may be initiated in the aqueous (persulfate) or in the non-aqueous phase (AIBN). On the decomposition of persulfates, sulfate and hydroxyl groups are introduced into macromolecules and microgels, thus influencing their surface properties [118,123-125]. By using AIBN as initiator a change of the chemical character of the surface and of the properties of the microgels is avoided. 

Takei, Y. G., Aoki, T., Sanui, K., Ogata, N., Sakurai, Y, and Okano, T. Dynamic contact angle measurement of temperature-responsive surfaces properties for poly(Af-isopropylacrylamide) grafted surfaces. Macromolecules, 1994, 27, 6163—6166. 

The parameters of treatment were chosen since these led to the most pronounced changes of polymer surface in our previous experiments [70-74]. It was observed elsewhere that plasma treatment of polymer macromolecules results in their cleavage, ablation, alterations of chemical structure and thus affects surface properties e g. solubility [75]. The chemical structure of modified polyethylene (PE) was characterized by FTIR and XPS spectroscopy. Exposition to discharge leads to cleavage of polymeric chains and C-H bonds followed by generation of free radicals which easily oxidize [10,76]. By FTIR spectroscopy the presence of new oxidized structures within whole specimen volume can be detected. IR spectra in the 1710-1745 cm" interval [71,77] from PE, exposed to... 

The surface properties of this kind of supramolecular systems are really scarce. An interplay between short - range van der Waals forces, ionic binding, chemical bonding, elastic/plastic compression, and long - range electrostatic interactions and capillary forces between macromolecules and surfaces seems to be responsible for the variety of observed interfacial behaviors. 

Chazelas, S., Razafindralambo, FI., de Chassart, Q.D., Paquot, M. 1995. Surface properties of the milk fat globule membrane competition between casein and membrane material. In Food Macromolecules and Colloids (E. Dickinson, D. Lorient, eds.), pp. 95-98, The Royal Society of Chemistry, Cambridge. 

The surface properties of a polymer are determined by the surface configuration rather than the configuration of a macromolecule. 

Elcctrokinctic phenomena such as the zeta potential and streaming potential can alter the surface properties of many porous inorganic membranes. The electrochemical properties of membrane surfaces can exert profound influence on the nature and magnitude of the interactions between the membrane and the liquid feed, thus affecting the permeating fluxes of the solvent and solute (or macromolecule/panicle) through the membrane pores. 

In conclusion, the versatility and power of FFF are not restricted to its ability to effect high-resolution separations and sizing of particles and macromolecules. FFF can also be used to probe the surface properties of colloidal samples. Such studies have great potential to provide detailed insight into the nature of adsorption phenomena. 

Most UF membranes are made from polymeric materials, such as, polysulfone, polypropylene, nylon 6, PTFE, polyvinyl chloride, and acryhc copolymer. Inorganic materials such as ceramics, carbon-based membranes, and zirconia, have been commercialized by several vendors. The important characteristics for membrane materials are porosity, morphology, surface properties, mechanical strength, and chemical resistance. The membrane is tested with dilute solutions of well-characterized macromolecules, such as proteins, polysaccharides, and surfactants of known molecular weight and size, to determine the MWCO. 

M. Muller and L. G. MacDowell (2000) Interface and surface properties of short polymers in solution Monte Carlo simulations and self-consistent field theory. Macromolecules 33, pp. 3902-3923... 

Part II Case Studies Macromolecules, Polymer Morphology and Polymer Surface Properties by AFM... 

The layered structure of a cast film is controlled by the surface properties during evaporation. Significant compositional gradients can be generated by making use of the natural tendencies of one polymer to migrate toward the air-polymer Interface and the other toward the substrate. Hydrophobicity/hydrophilicity of macromolecules is often cited as the driving force (27, 28). 

The surface properties of macromolecules most likely arise from the unfolding of the long chains in the surface region. Flory and Huggins (8) developed a theory in 1942 for polymer solution, and Singer (9) later applied it to surface films. Since then Frisch and Simha (10) and Silber-berg (11) proposed additional models which account for those portions of the polymer chain that are pushed into the bulk phase, or even lifted off the surface, upon compression. 

The adsorption of charged macromolecules modifies considerably the electrical surface properties of colloid particles already at very low concentration. Figure 1 shows typical dependence of the HF electro-optical effect on the polyelectrolyte concentration. One observes a steep decrease of the effect with increasing polyelectrolyte concentration, which turns to an increase at superequivalent adsorption of the oppositely charged polymer onto the par-... 

Macromolecules publishes original research on all fundamental aspects of mac-romolecular science, including synthesis polymerization mechanisms and kinetics and chemical modification, solution/mclt/solid-state characteristics, and surface properties of organic, inorganic, and naturally occurring polymers. Manuscripts that present innovative concepts, experimental methods or observations, and theoretical approaches in fundamental poly-... 

The results of experiments with different colloids demonstrate some of the ways in which macromolecules of various sizes, shapes, and surface properties may interact to form, in some cases, ordered solutions similar to liquid crystals and, in other cases, three-dimensional networks with the properties of a solid and how the order or the structure present determines the mechanical properties. 

Instabilities in UTR films can also be manifested as discontinuities in the thermophysical properties of the films due to interfacial effects and polymer cooperative and surface dynamics. Polymer surfaces are regions of enhanced molecular mobility as compared to the bulk, given the decreased constraints on macromolecules at a free surface. The orientation of the surface groups is affected by the nature of the interfacing environment. This implies that polymeric surfaces can restrucmre (in terms of orientation of surface functionalities, concentration of surface groups, etc.) in response to a change in the interfacial phase, in order to adjust their surface properties to the properties of the interfacial medium. °... 

---