Water swellable coating

G. C. Berry and M. Dror, Modification of Polyurethanes by Interpenetrating Polymer Network Formation with Hydrogels, Am. Chem. Soc. Div. Org. Coat. Plast. Chem. Pap. 38(1), 465 (1978). Polyether-urethane-urea block copolymers with crosslinked HEMA, NVP, or acrylamide. IPNs and gradient IPNs for biomedical purposes. Strength, water swellability, and good blood compatibility. 

Thick coating consisting of water-insoluble, non-swellable polymers... 

Swellable hydrogels, (IV), used for sensor coatings were prepared by Van Antwerp [4] and were capable of water uptake of at least 200% by weight. 

Materials used to coat pharmaceutical products are primarily based on acrylic and cellulosic polymers and the aqueous solubility characteristics of these compounds generally dictate their uses. Sustained release coatings are water-insoluble or swellable films through which the medicament slowly diffuses. Drug products coated with these polymers are administered less frequently and the high peak plasma concentrations... 

The core may be a water-soluble polymer, an inert salt or, as in the case of metoprolol fumarate, the drug itself, whose saturated solution has an osmotic pressure of 32.5 atm. The osmotic tablet of nifedipine is described in detail in Fig. 8.38, which shows the semipermeable cellulose acetate coating, the swellable hydrogel layer of polyoxyethylene glycol and hydroxypropylmethylcellulose (HPMC) and the dmg chamber containing nifedipine in HPMC and PEG. 

X HE RELATIVE COST OF MANUFACTURING hydrophobically modified, water-soluble polymers is the primary determinant in their market acceptance. The lowest-cost associative thickeners used in coating formulations are hydrophobically modified, alkali-swellable emulsions (HASE). The extensive history leading to the development of this technology is reviewed in the preceding chapter their utilization and limitations are discussed in Chapters 27 and 28. 

Features Preneutralized requires no pH adjustment alkali-swellable exc. balance of water holding and thickening efficiency rec. for heavy coat weights applies. 

---