Abstract
Cellulose acrylate acetate, which has double bonds in the side chain, was synthesized and methyl methacrylate was grafted onto the cellulose ester in the homogeneous systems using benzoyl peroxide as an initiator and dioxane or cyclohexanone as a solvent.
The following results were obtained:
1) Grafting efficiency was low and was 28.1% at the most. The values at 80°C were larger than at 60°C. At 80°C the grafting in dioxane as a solvent resulted in a higher degree of grafting compared to that in cyclohexanone, but no difference was observed among solvents at 60°C.
2) The formation of homopolymer was larger at 80°C than at 60°C, and no difference was observed among solvents.
3) Although the reaction was carried out in the homogeneous systems, in which both the trunk polymer and the graft copolymer were dissolved, a number of grafted side chains per trunk polymer was less than unity irrespective of the reaction conditions. This is supposingly attributed to the difficulty of the attack on initiator and propagating polymer radicals on double bonds in the cellulose esters due to the steric hindrance of acetyl groups existing in the cellulose ester, and consequently the smaller reactivity of double bonds in this cellulose ester.
4) The graft copolymerization was also carried out using cellulose acetate instead of cellulose acrylate acetate under the same reaction conditions. Almost the same amount of homopolymer was obtained as in the case of cellulose acrylate acetate, but no graft copolymerization occurred. Accordingly, the double bond in acryloyl group was definitely involved in the reaction.
5) The grafted side chains could be perfectly isolated from the graft copolymers by hydrolyzing the trunk polymer for 12 hours at 105°C using a dioxane-HCl system which can dissolve both the graft copolymer and the side chain polymer.
