Degradation and grafting of hydroxyethyl cellulose during emulsion polymerization

Degradation of hydroxyethylcellulose (HEC) in aqueous solution at 80 °C has been studied with the observations that degradation is rapid in the presence of ammonium persulfate (APS), but slow with 4,4′-azobis(4- cyanopentanoic acid), and that hydrolytic degradation is insignificant. Acrylic emulsion polymerizations performed at 80 °C with HEC as the principal colloid stabilizer and APS as initiator have also been studied. In the presence of acrylic monomers, the dominant reaction leads to grafting of HEC chains to the latex particles. However, during periods when monomer is absent the HEC chains degrade and those that are grafted to latex particles release free HEC chain fragments to the aqueous phase. These observations are discussed in relation to a proposed mechanism for degradation and grafting of HEC.