LITERATURE SURVEY ON CROS SLINKING REACTIONS 

 Polyvinyl Alcohol 



Polyvinyl alcohol is widely used in the manufacture of water- 

 soluble films for packaging. Fibers can be produced by passing an 

 aqueous solution of polyvinyl alcohol through spinnerets into an 

 aqueous solution of sodium sulfate, after which it is crosslinked with 

 formaldehyde. Direct formaldehyde crosslinking of polyvinyl alcohol 

 has also been accomplished in the presence of mineral acids, 2, 3 ^^d 

 acrolein (at pH 6.5)^ and polyacrolein (in neutral and acid solution) 

 have also been used. Aldehydes and aldehyde reaction products, 7 j° 

 aliphatic dicarboxylic acids usually in the presence of mineral acids, 9~12 

 quinone,13 formamide. N,N-methylenesbisacrylamide,-'-^ N- 

 methylolacrylamide, 5-hydroxy-5-H-dibenz [c,e\ azepine,-^' esters of 

 propiolic acid,-'-° dime thy lene thiourea, ■'■^ trichloroethyl phosphite and 

 diacetoxysiloxane,^ and cyanuric chloride, maleic anhydride, ^^ 

 methacrylic acid, 2^ polyamide-epichlorohydrin resin,2'^ and poly (vinyl- 

 methyl ether /maleic anhydride) ^5 have been reported as crosslinking 

 agents for polyvinyl alcohol. 



Insolubilization, gelation, or crosslinking of polyvinyl alcohol 

 can occur when it is treated with inorganic compounds such as ammonium 

 perborate,-^" cupric ion, 27 hydrochloric or sulfuric acid, 28 cupric 

 dichromate ,24 and ammonium zirconyl carbonate.^" 



Acrylamide and Polyacrylamide 



Mixtures of acrylamide and N,N-methylenebisacrylamide can be 

 polymerized and crosslinked in dilute aqueous solutions 30,31 ^q form 

 stiff gels for soil stabilization. Polyacrylamide, when crosslinked 

 with polyacrolein, forms a tough, clear, insoluble gel, but when cross- 

 linked with gelatin, cellulose polymethyl ether, or polyvinyl 

 pyrollidone, viscous solutions are formed. ^'t 



Other Compounds 



Methyl cellulose can be crosslinked by the dipropiolate of poly- 

 ethylene glycol (MW 300) to yield films which are highly softened by 

 but insoluble in cold or boiling water. Dimethylol urea, dialdehyde 

 starch, glyoxal, and formaldehyde crosslink gelatin and the dipropiolate 

 of tetraethylene glycol reacts with starch to form a compound which is 

 insoluble in cold and boiling water. ^^ Polyacrolein treated with 

 ethylene glycol yields a highly crosslinked film which is insoluble in 

 boiling water. ^ Poly(methylvinyl ether /maleic anhydride) (PVM/MA) 

 reacts with di-, tri-, and polyhydroxy compounds to form materials with 

 some water resistance. ^^ A crosslinked ester is formed when PVM/MA 

 reacts with 2-butene-l ,4-diol and polyvinylpyrrolidone in solution. 3b 

 Copolymers derived from vinylpyrrolidone and water-insoluble comonomers 



