Equipe Systèmes Polymères Complexes, Institut de Chimie et des Matériaux Paris‐Est, UMR 7182, 2‐8 rue Henri Dunant, 94320 Thiais, France
Abstract:
The self‐assembling properties of hydrophobically modified (N‐isopropylacrylamide) have been investigated by dynamic light scattering and rheological measurements. Size of the globules and transmission of the solutions vary strongly in the same range of temperature. The presence of hydrophobic groups leads to contraction of the globules' size compared to poly(N‐isopropylacrylamide) (PNIPAM). The viscoelastic properties of the samples in aqueous solution have been investigated as a function of copolymer concentration, structure of the hydrophobic group (dodecyl or adamantyl group), substitution level (1–5%) and over a temperature range covering the lower critical solution temperature (LCST). At high concentration and high level of adamantyl substitution, gelation is observed several degrees before the phase transition. A physical network is formed due to the strong hydrophobic interactions, and this physical gel undergoes phase transition without macroscopic phase separation.
