Polymer chains hydrophobic regions

These four types of forces are responsible for the adaptive behavior of smart gels. The different forces come into play when the network of polymer chains composing a gel is disturbed, (a) Charged ionic regions can attract or repel each other, (b) Nonpolar hydrophobic regions exclude water, (c) Hydrogen bonds may form from one chain to another, (d) Dipole-dipole interactions can attract or repel chains. 

It implied that the motion of P P is suppressed by the microviscosity created by hydrophobic contracted polymer chain aggregation. On the other hand, the ryjda jj of PQ3P dissolved in PIPAAm-b-PBMA micelle solutions were markedly lowerthan those of PIPAAm solutions overthe entire temperature region owing to highly compact cores of aggregated PBMA chains. 

Film formation of PUDs involves coalescence of the particles and the formation of a continuous film. A PUD particle has a hydrophilic shell and a hydrophobic core. Upon film formation, there is a very slow process of coalescence on a molecular level whereby there is a physical barrier to polymer chain mixing. The resultant coatings have hydrophilic and hydrophobic regions, which create a more water-permeable film (Chainey etaL, 1985). 

Micelle-like junction zones are formed by methylcel-lulose and polyethyloxylene polypropyloxylene block copolymers (poloxamers). Although the polymers differ in chemical structure, both have hydrophobic regions in their chains the di- and trimethyl-o-glucose residues of methylcellulose and the polypropyloxylene block of poloxamer. Another feature common to the... 

On strongly adhesive substrates (Fig. 14b, c), friction increases with the substrate hydrophobicity in the low-velocity region, showing a weak velocity-strengthening, and a dramatic friction transition at around v = 10 m/s. This value is one order lower than the characteristic velocity of the polymer chain Vf = /Tf. The friction behavior is satisfactorily described by the repulsion-adsorption model below the transition region The friction transition is explained in terms of the elastic... 

Hydrophobic regions can be one or two small, well-defined blocks of pendant hydrophobic moieties in an otherwise water-soluble polymer (2-4). An example is a water-soluble sulfonated BAB triblock copolymer where B is hydrophobic f-butylstyrene and A is vinyltoluene (2). However, hydro-phobic regions can also be less well-defined as well as more numerous in a polymer molecule than is the case for a triblock copolymer (5-22). For example, pendant alkyl esters appear to have been randomly incorporated in styrene-maleic anhydride (5) and vinyl benzyl ether-styrene-maleic anhydride (6-ii) copolymers. Also, alkyl polyoxyethylene acrylate monomers can be copolymerized with acrylamide to yield copolymers with pendant hydrophobic chains (12-15). More recently it was found (16-22) that small amounts of water-insoluble monomers that are solubilized by surfactants into aqueous solutions of a hydrophilic monomer produce copolymers with pendant hydrophobic chains, but the size, number, and nature of the hydro-phobic regions has not been determined. 

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