We have synthesized aldehyde compounds with branched methylene groups by a LiCl catalyst. The number-average molecular weight and the weight-average molecular weight of the polymer, determined by MS, were 6.5×103 and 6.5×103, respectively. The synthesized polymer showed a photoluminescence peak at 447 nm. However, the fluorescent strength did not show enough fluorescence. The TGA measurements of the polymer, showed that the polymer had a high thermal stability with a 10% thermal weight loss initiation temperature of 390°C.