A poly(vinyl alcohol) (PVA)/sodium acrylate (AANa) copolymer was synthesized to improve the water solubility of PVA at the ambient temperature. Furthermore, a series of temperature-responsive acetalyzed poly (vinyl alcohol) (APVA)-co-AANa samples of various chain lengths, degrees of acetalysis (DAs), and comonomer contents were prepared via an acid-catalysis process. Fourier transform infrared and H-1-NMR techniques were used to analyze the compositions of the copolymers. The measurement of the turbidity change for APVA-co-AANa aqueous solutions at different temperatures revealed that the lower critical solution temperature (LCST) of the copolymers could be tailored through the control of the molecular weight of the starting PVA-co-AANa, DA, and comonomer ratios. Lower LCSTs were observed for APVA-co-AANa with a longer chain length, a higher DA, and fewer acrylic acid segments. In addition, the LCSTs of the APVA-co-AANa aqueous solutions appeared to be salt-sensitive. The LCSTs decreased as the concentration of NaCl increased. Moreover, atomic force microscopy images of APVA-co-AANa around the LCST also proved the temperature sensitivity. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 26982703, 2008