Polymers linear hydrophilic

The hydroxylic content of the dextran sugar backbone makes the polymer very hydrophilic and easily modified for coupling to other molecules. Unlike PEG, discussed previously, which has modifiable groups only at the ends of each linear polymer, the hydroxyl functional groups of dextran are present on each monomer in the chain. The monomers contain at least 3 hydroxyls (4 on the terminal units) that may undergo derivatization reactions. This multivalent nature of dextran allows molecules to be attached at numerous sites along the polymer chain. 

Fig. 9.18 The polymer spacer concept for the construction of a biomimetic cell membrane on solids. Mesogenic units, coupling groups and the flexible polymer can be combined either in form of a statistical terpolymer (above). Variation of the ratio of the three monomers allows an easy tuning of the system. In an alternative system, an end-functio-nalized linear hydrophilic polymer chain bearing a coupling group at the proximal and the mesogen at the distal end was employed.

In recent years, there has been much interest in the study of polymer complexes, particularly in relation to their catalyst properties, thermostability and biomedical effects. Mainly these studies have been directed towards the use of insoluble polymers. An account of the soluble polymeric metal complexes and their catalytic activity has been published recently A brief outline of the studies in relation to the n M-chelation of some linear hydrophilic polymers and their functional derivatives with chelating groups and some polymeric molecular complexes is given in this section. 

One might speculate on a number of chemical and physical factors that govern protein adsorption behavior. Previous experiments point to the importance of hydrophilicity as an influential factor (6), but this is certainly not the sole factor. In this polymer system, hydrophilicity (as governed by the surface concentration of HEM A) increases linearly with the bulk HEM A composition (11). The surface of a protein which is also soluble in aqueous media is probably of a polar nature. If protein adsorption could be characterized by polar interactions, then an adsorption trend that would parallel the... 

The relatively simple and specific primary immune response to haptens on linear hydrophilic polymers, consisting of only a few types of well defined chemical subunits, makes them useful in immunological investigations. In studies on DNP-polyacryl-amide systems, a general theory of the initial phase of immune response was developed This theory is based on the quantized model of cellular stimulation,... 

In gel-ffee sieving systems, the medium consists of an electrolyte solution containing linear hydrophilic polymers (e.g., polyethylene glycols). Separation according to size is obtained because of the resistance provided by entangled polymers. Compared to gel CE, gel-ffee sieving is easy to perform, the capillary system has a long... 

To realize the long-term hydrophilicity of the blend polymer membranes, the key point is to improve the stability of the hydrophilic component on the membrane surface and matrix. To this end, amphiphilic polymers have been adopted to replace linear hydrophilic PEG and PVP in membrane preparation. Theoretically, improved interactions among the hydrophobic segments in amphiphilic polymers and the fluoropolymer can improve the compatibility of the blend, and thus enhance the stability of amphiphilic polymer in the membrane matrix. Three kinds of amphiphilic polymers, viz., triblock copolymer of poly(ethylene oxide)-( -poly(propylene oxide)-ft-poly(ethylene oxide) (EPE), comb-like copolymer of polysiloxane with poly(ethylene oxide) and poly(propylene oxide) side chains (ACPS), and the hyperbranched star copolymer of polyester-g-methoxyl poly(ethylene glycol) (HPE-g-MPEG), have been... 

The neutral hydrophilic surface and the wide range of pore diameters available for SynChropak GPC allow many compounds from small peptides to nucleic acids and other polymers to be analyzed. Table 10.2 lists the approximate exclusion limits for both linear and globular solutes. Although this information... 

Anionic and neutral polymers are usually analyzed successfully on Syn-Chropak GPC columns because they have minimal interaction with the appropriate mobile-phase selection however, cationic polymers adsorb to these columns, often irreversibly. Mobile-phase selection for hydrophilic polymers is similar to that for proteins but the solubilities are of primary importance. Organic solvents can be added to the mobile phase to increase solubility. In polymer analysis, ionic strength and pH can change the shape of the solute from mostly linear to globular therefore, it is very important to use the same conditions during calibration and analysis of unknowns (8). Many mobile phases have been used, but 0.05-0.2 M sodium sulfate or sodium nitrate is common. 

Reactions of this type are quite popular and widely used to introduce hydrophilic and ionogenic groups into linear polymers as well as directly into polymer networks. These reactions include hydrolysis (PAAm, PAAc and their analogs from PAN, PVA from poly (vinyl acetate), oxyethylation and oxymethylation of starch and cellulose, sulfurization, and other reactions. These processes are of industrial importance, well studied and widely reviewed. 

Amino acids, the building blocks of giant protein molecules have a carboxyl group and an amino group attached to the same carbon atom. A protein is a linear polymer of amino acids combined by pepfide linkages. Twenfy different amino acids are common in proteins. Their side chains, which have a variety of chemical properties, control the shapes and functions of proteins. Some of these side chains are hydrophobic, others are hydrophilic, and still others occur either on the surface or the interiors of proteins. 

The presence of a large number of chain-ends in the fully synthesized dendrimer molecules makes them highly soluble and also readily miscible, for example with other dendrimer solutions. The solubility is controlled by the nature of the end-groups, so that dendrimers with hydrophilic groups, such as hydroxyl or carboxylic acid, at the ends of the branches are soluble in polar solvents, whereas dendrimers with hydrophobic end-groups are soluble in non-polar solvents. The density of the end-groups at the surface of the dendrimer molecule means that they have proportionately more influence on the solubility than in linear polymers. Hence a dendritic polyester has been shown to be more soluble in tetrahydrofuran than an equivalent linear polyester. 

The overall objective of this chapter is to review the fundamental issues involved in the transport of macromolecules in hydrophilic media made of synthetic or naturally occurring uncharged polymers with nanometer-scale pore structure when an electric field is applied. The physical and chemical properties and structural features of hydrophilic polymeric materials will be considered first. Although the emphasis will be on classical polymeric gels, discussion of polymeric solutions and nonclassical gels made of, for example, un-cross-linked macromolecular units such as linear polymers and micelles will also be considered in light of recent interest in these materials for a number of applications... 

In the most succinct sense, a hydrogel is simply a hydrophilic polymeric network cross-linked in some fashion to produce an elastic structure. Thus any technique which can be used to create a cross-linked polymer can be used to produce a hydrogel. Copolymerization/cross-linking free radical polymerizations are commonly used to produce hydrogels by reacting hydrophilic monomers with multifunctional cross-linkers. Water-soluble linear polymers of both natural and synthetic origin are cross-linked to form hydrogels in a number of ways ... 

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