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Handbook of Size Exclusion Chromatography and Related ...

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effect <strong>of</strong> the tincture <strong>of</strong> iodine solution but retains the germicidal activity <strong>of</strong><br />

the iodine.<br />

Because <strong>of</strong> the excellent solubility <strong>of</strong> PVP in water, the dissolution rate <strong>of</strong><br />

many drugs <strong>and</strong> compounds that are difficult to dissolve can be significantly<br />

improved if they are coprecipitated with PVP. PVP is amphiphilic in nature <strong>and</strong> is<br />

slightly surface active. It is frequently used in industries as a suspending aid <strong>and</strong> a<br />

protective colloid for polymers, emulsions, <strong>and</strong> lattices. PVP is also used as a dye<br />

stripper in the textile industry <strong>and</strong> in detergent formulation to prevent soil <strong>and</strong> dye<br />

redeposition. Because <strong>of</strong> its good adhesive <strong>and</strong> cohesive strengths <strong>and</strong> excellent<br />

water solubililty, PVP is one <strong>of</strong> the most widely used tablet binders for the<br />

pharmaceutical industry. It is also used as the major component in glue sticks <strong>and</strong><br />

for bonding medical devices to a patient’s skin.<br />

The hydrophilic, hydrophobic, <strong>and</strong> ionic nature <strong>of</strong> PVP can be modified<br />

by copolymerization to enhance the properties <strong>of</strong> PVP for certain applications.<br />

Nonionic, anionic, <strong>and</strong> cationic VP copolymers have all been commercialized.<br />

A wide range <strong>of</strong> vinyl pyrrolidone <strong>and</strong> vinyl acetate copolymers, which are<br />

nonionic, have been made with optimized amphiphilicity <strong>and</strong> solubility in water or<br />

alcohol for the cosmetic <strong>and</strong> pharmaceutical industries. The surface activity <strong>of</strong><br />

PVP can be further enhanced by copolymerization with acrylic acid. Vinyl<br />

pyrrolidone <strong>and</strong> acrylic acid copolymers, which are anionic in their major<br />

applications, with different molar ratios have been developed with wellbalanced<br />

surface, associative, <strong>and</strong> film-forming properties for industrial<br />

applications.<br />

Quaternized copolymers <strong>of</strong> vinyl pyrrolidone <strong>and</strong> dimethylaminoethylmethacrylate,<br />

which is cationic, have been developed for the hair care <strong>and</strong> skin<br />

care industries because <strong>of</strong> their optimal substantivity, minimum buildup, <strong>and</strong><br />

ability to form nontacky <strong>and</strong> continuous films. Other important comonomers<br />

include vinyl alcohol, styrene, maleic anhydride, acrylamide, acrylonitrile,<br />

crotonic acid, <strong>and</strong> methyl methacrylate.<br />

2 MOLECULAR WEIGHT GRADES OF IMPORTANT<br />

VP-BASED POLYMERS<br />

Many different molecular weight grades <strong>of</strong> VP-based polymers, characterized by<br />

viscosity, are available commercially. The determination <strong>of</strong> viscosity is historically<br />

satisfactory for quality assurance purposes; however, most physical properties <strong>of</strong><br />

polymers are directly related to molecular weight (1). For example, the glass<br />

transition temperature <strong>and</strong> tensile strength <strong>of</strong> amorphous polymers are known to<br />

depend on molecular weight. The melt viscosity <strong>of</strong> polymers <strong>and</strong> the bulk<br />

viscosity <strong>of</strong> concentrated polymer solutions are also known to depend on<br />

molecular weight.<br />

© 2004 by Marcel Dekker, Inc.

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