A study of blending and complexation of poly(acrylic acid)/poly(vinyl pyrrolidone)

Poly(acrylic acid) (PAA) and poly(vinyl pyrrolidone) (PVP) were chosen to prepare polymer complex and blends. The complex was prepared from ethanol solution and the blends were prepared from 1-methyl-2-pyrrolidone solution. DSC results show that the Tgs of the PAA/PVP blends lie between those of the two constituent polymers, whereas Tg of the PAA/PVP complex is higher than both blends and the two constituent polymers. TGA results show that degradation temperature, Td, of PAA increases upon adding PVP in the blend, but thermal stability of the complex is higher than that of the blends as reflected by the higher Td. Both FTIR and high-resolution solid state NMR show strong hydrogen bonding between PAA and PVP by showing significant chemical shift. The T1ρ(H) measurement shows that the homogeneity scale for the blend is at ∼20 Å and that for the complex is ∼15 Å.