e (EGDMA), n-vinyl-2pyrrolidone (NVP), methacrylic acid (MA), and vinyl acetate (VAC); polycrylamide; gelatin; gums and polysaccharides such as gum arabic, gum karaya, gum tragacanth, guar gum, gum benzoin, and alginic acid and their salts; polyethylene glycol (PEG); polypropylene glycol (PPG); and clays or other swellable minerals such as bentonite and montmorillonite.