A photochemical reaction between acridine and poly(methyl methacrylate-co-methacrylic acid) (PMCA) was studied in benzene to build a recyclable polymer photodegradation system. The illumination of acridine in the presence of PMCA with 365-nm light induced the bleaching of acridine and the degradation of PMCA. The average molecular weight of the degraded polymer decreased rapidly for the first 30 min of the photolysis. A nonvolatile product of this reaction was found to have a 2-methyl-2-properyl end group. The efficiency of the PMCA scission by this method was 30 times as large as that of poly(methyl methacrylate). These results suggest that an efficient photochemical polymer decomposition system can be built by adding the mixing process of a little methacrylic acid into the synthetic processes of general vinyl polymers. (c) 2005 Wiley Periodicals, Inc.