Adhesive RAFT agents for controlled polymerization of acrylamide: effect of catechol-end R groups

Abstract

Synthesizing polyacrylamide (PAM) inorganic nanocomposites with stable tethering and controlled polymer length has been elusive. Herein, we report on the synthesis of trithiocarbonates with several catechol end R groups (as anchors) that differ in their carbonyl α-substituents. These so-called adhesive RAFT agents were subsequently examined in batch RAFT polymerization of the acrylamide (AM) monomer to study their living characteristics. The catechol-end trithocarbonates (Dopa-CTAs) and catechol-end PAM structures (≤46 kDa) were confirmed via 1D (¹H and ¹³C) and 2D (gHSQC, gHMBC) NMR. Subsequent anchoring of the end-functionalized PAM (grafting to) via catechol induced linkage to γ-alumina nanoparticles was successful, giving good correlation based on ATR-FTIR, DLS and TGA analyses. This unique methodology enables PAM-inorganic nanocomposites to be synthesized with stable tethering without significant rate retardation.