Abstract:

Anew series of structurally controllable dual hydrophilic diblock copolymers poly(methacrylate acid)-b- poly(N-(2- methacryloylxyethyl) pyrrolidone), PMAA-b-PNMP including PMAA101-b-PNMP153, PMAA101-b- PNMP₂₄₀, PMAA101-b-PNMP₄₂₀, and PMAA₁₀₁-b-PNMP₅₃₉, were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and characterized by gel permeation chromatography (GPC) and ¹H nuclear magnetic resonance (NMR). The pH- and temperature-induced micellization behavior of PMAA-b-PNMP in aqueous solution was confirmed by static light scattering (SLS) and dynamic light scattering (DLS) and cryogen transmission electron microscopy (cryo-TEM) techniques. The polymerization degree of PNMP strongly affects the micellization behavior. Generally, with higher polymerization degree, the micellization pH was lower and the micellization temperature was higher. During the micellization processes, the weakness of the hydrogen bond interactions between water and PNMP or PMAA and the strength in the inter- and intra-chain interactions between PNMP and PMAA segments are dominant during the pH-induced micellization, as revealed by the pDdependent ¹H NMR spectra. However, the weakness in the hydrogen bond interactions between water and PNMP is the major cause of the temperature-induced micellization process. We also provide solid evidence for the ability to control the size of Au NPs by adjusting the pH in the presence of PMAA-b-PNMP. Specifically, with higher pH, the size of the Au NPs was smaller.

Key words: PMAA-b-PNMP, Micellization, pH, Temperature, Gold nanoparticle