Various poly(alkyl crotonate)s (PRCrs) were synthesized by group-transfer polymerization (GTP) using organic superacid catalysts such as 1-[bis(trifluoromethanesulfonyemethyl]-2,3,4,5,6-pentafluorobenzene (C6H5CHTf2) and 1-trimethylsiloxyl-1-methoxy-2-methyl-1-propene (MTS) as an initiator. Under the optimized reaction conditions, the corresponding poly(ethyl crotonate) (PEtCr) was obtained with a narrow molecular weight distribution (MWD = 1.14) in quantitative yield (>99%). The thermal stabilities of the PRCrs obtained by organic acid-catalyzed GTP were generally superior to those of poly(alkyl methacrylate)s. The glass-transition temperature (Tg) of poly(methyl crotonate) (PMeCr) (122 degrees C) was higher than that of poly(methyl methacrylate) (PMMA) prepared by GTP (104 degrees C). The 5% weight loss temperature (T-d5) of PMeCr (359 degrees C) was also higher than that of PMMA (304 degrees C). The values of the total light transmittance (T-t) (reaching 91.9%) and haze (<5%) of the PRCr films were similar to those of both PMMA films and glass plates.