Interface characteristics liquid-polymer

These two examples are typical of to what extent polymer—surfactant interactions in aqueous solution can influence the solid-liquid interface characteristics. In the present case, according to the nature of the solid surface, either the polymer or the surfactant can act as a linker to the surface for the other which has no reason to spontaneously adsorb onto it. The practical outcomes of such systems are numerous. At this stage, it is interesting to review some other studies dealing with similar systems, to illustrate the high versatility of polymer-surfactant associations as potential solid-surface modifiers. The most well-known examples are listed in Table 1. 

Thick-fihn pastes are mixtures of solid particulates (metal powders, frit, etc.) suspended in polymeric solutions. The rheological properties of the paste are directly influenced by the relative amounts of each ingredient and interactions between the solid, polymer, and solvent. Additives such as dispersants/surfactants and rheology modifiers are also commonly added to the paste to improve paste performance. The average particle size of the powders is in the range of approximately 0.1 to 10 /im for most thick-fihn pastes. In this size range, the specific surface area is large (several m /g to 100 mVg) and the interparticle interactions are dominated by the solid-liquid interface characteristics or surface chemistry of the system. 

Synthetic surfactants and polymers are probably most often used to modify the characteristics of a solid surface, i.e., they function at the solid - liquid interface, such as in the processes of detergency, lubrication, or the formation of adhesive bonds. The performance of modem FT - IR spectrometers is such that many new applications to the characterization of the solid - liquid interface, particularly in kinetics studies, are possible. Reflection - absorption spectroscopy and attenuated total reflectance (ATR) techniques have been applied to "wet" interfaces, even the air - water interface, and have figured prominently in recent studies of "self -assembled" mono - and multilayers. 

In the various sections of this chapter, I will briefly describe the major characteristics of FT-IR, and then relate the importance of these characteristics to physiochemical studies of colloids and interfaces. This book is divided into two major areas studies of "bulk" colloidal aggregates such as micelles, surfactant gels and bilayers and studies of interfacial phenomena such as surfactant and polymer adsorption at the solid-liquid interface. This review will follow the same organization. A separate overview chapter addresses the details of the study of interfaces via the attenuated total reflection (ATR) and grazing angle reflection techniques. 

A new class of water soluble cellulosic polymers currently receiving attention Is characterized by structures with hydrophobic moieties. Such polymers exhibit definite surface activity at alr-llquld and liquid-liquid Interfaces. By virtue of their hydrophobic groups, they also exhibit Interesting association characteristics In solution. In this paper, results are presented on the solution and Interfaclal properties of a cationic cellulosic polymer with hydrophobic groups and Its Interactions with conventional surfactants are discussed. 

The membrane in a broad sense is a thin layer that separates two distinctively different phases, i.e., gas/gas, gas/liquid, or liquid/liquid. No characteristic requirement, such as polymer, solid, etc., applies to the nature of materials that function as a membrane. A liquid or a dynamically formed interface could also function as a membrane. Although the selective transport through a membrane is an important feature of membranes, it is not necessarily included in the broad definition of the membrane. The overall transport characteristics of a membrane depends on both the transport characteristics of the bulk phase of membrane and the interfacial characteristics between the bulk phase and the contacting phase or phases, including the concentration polarization at the interface. The term membrane is preferentially used for high-throughput membranes, and membranes with very low throughput are often expressed by the term barrier. ... 

When a-helices form in synthetic polypeptides at the air-water interface, their rigid rod-like nature promotes side-by-side association of the molecules into highly ordered arrays or micelles, just as liquid crystalline structures form in solution at sufficiently high concentration (II). When such a monolayer is compressed on a Langmuir trough, the pressure rises when the surface area has reached a value expected for close-packed a-helices. At a pressure which appears a characteristic for the polymer, a transition is observed which is either an almost flat plateau in the pressure-area curve or simply an inflexion, flrst noted by Crisp (13), if the side chain is short (12). An inflexion also occurs if the side chain is inflexible. Normally the pressure rises again as the area is decreased, and in some instances further transitions are observed (14). 

Pefferkorn E, Dejardin Ph, Varoqui R. Derivation by hydrodynamics of the structural characteristics of adsorbed polymers at liquid-solid interfaces. J Colloid Interface Sci 1978 63 353-363. 

Very recently, this investigation method has been extended to two dimensions. Improvements have been made concerning the measurement technique of the surface osmotic pressure of polymers spread on a liquid-air interface. Vilanove and Rondelez thus measured, for the first time in 1980, the characteristic size exponent v of chains in a two-dimensional space. 

Surface science is an invisible yet exceedingly important branch of physics and organic chemistry that studies the behavior and characteristics of molecules at or near the surface or interface. The interface can be between solids, liquids, gases, and combinations of these states. Sophisticated apparatus have been developed to identify and quantify surfaces and interfaces. Polymer surfaces are of special interest in industrial and biological applications examples of the latter include dental implants and body part prosthetic devices. Modification of surfaces of these devices allows formation of controlled interfaces to achieve characteristics such as bondability and compatibility. 

A number of miscible polymer blends are only completely miscible and form one-phase systems over a limited concentration, temperature and pressure range. Under certain conditions of temperature, pressure and composition, miscible binary blends may phase separate into two liquid phases with different compositions. Important characteristics of this type of blends are the overall blend composition, the morphology and the composition of the different phases as well as the nature of the interface between the phases. 

Typically, the segregated phase has a smaller characteristic length scale than the continuous phase. In a monomer-flooded emulsion polymerization, the aqueous continuous phase will contain monomer drops and polymer particles, although large monomer drops may also contain smaller water droplets or polymer particles (if crosslinked or insoluble). This is the consequence of a thermodynamic principle that acts in the direction of a constant chemical potential for all species, throughout the whole system. In other words, there is a driving force that pushes all of the components of a system to be present in different proportions in all of its phases. This principle has been proven in spontaneous emulsification experiments, where droplet formation is observed on either side of the liquid-liquid interface [7]. Moreover, the chemical potential is size-dependent at the colloidal scale and hence, particles of different size will possess different compositions. 

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