Homogeneous\nReversible Addition Fragmentation Chain\nTransfer Synthesis of Amphiphilic Poly(Styrene‑<i>b</i>‑Acrylamide) Copolymers and Their Solution Characterization:\na Thermogelating and Salinity Resistant Viscosifier from Largely Av

Even though styrene\nand acrylamide are among the most abundant\nmonomers, their copolymers are understudied due to the difficulties\nconnected to their synthesis, especially if well-defined structures\nare desired. This study explores the synthesis and solution properties\nof poly(styrene-<i>b</i>-acrylamide) block copolymers. We\nreport for the first time the synthesis of such diblock copolymers\nwith RAFT polymerization in homogeneous conditions, utilizing DMSO\nas a common solvent. Despite their nonpolyelectrolyte nature and a\nvery low content of the hydrophobic comonomer, poly(styrene-<i>b</i>-acrylamide) diblock copolymers have been found to be remarkably\ngood viscosifiers for water. Gelation concentration as low as 1 wt\n% was observed for copolymers containing as little as 1 mol % of styrene\nconstituting a block less than 10 repeat units long. An irreversible\ngelation upon heating was observed according to a new mechanism of\nmicrogel particle hydration, which is proposed for applications in\nthe fields of biomaterials and 3D printing. The properties are speculated\nto arise from strong hydrogen bonding within the PAM domains. Amid\nthe current growing focus on polyelectrolytes, this work highlights\nubiquitous acrylamide as a building block in nonpolyelectrolyte block\ncopolymers for design of smart soft materials.