UV absorbance(A) of self-assembled films of poly(dimethyldiallyl ammonium chloride)(PDDA) and poly(styrene sulfonate)(PSS) with various concentrations of polyelectrolyte(c__P) at different concentrations of sodium chloride was investigated. It was found that the A～c__P curves display a discontinuous phenomenon. And the turning point concentration, at which the A～c__P curve starts to display a discontinuous phenomenon, is in good agreement with the critical concentration c* of PSS or PDDA polyelectrolyte solutions. The results above attribute to the change of chain shape of polyelectrolytes in solutions caused by c__P and c(NaCl). Thus, it is inferred that chain shape of polyelectrolyte in solutions affects the thickness of PSS/PDDA multilayer films.
