Synthesis of Degradable Polysulfamides via Sulfur(VI) Fluoride Exchange Click Polymerization of AB-Type Monomers

Abstract

Polysulfamides are the −SO₂– analogues of polyureas and form an intriguing family of polymers containing hydrogen-bond donor and acceptor groups. However, unlike polyureas, their physical properties are mostly unknown because of the scarcity of synthetic methods to access such polymers. Herein, we report an expedient synthesis of AB monomers for the synthesis of polysulfamides via Sulfur(VI) Fluoride Exchange (SuFEx) click polymerization. Upon optimization of the step-growth process, a variety of polysulfamides were isolated and characterized. The versatility of the SuFEx polymerization allowed structural modulation of the main chain through the incorporation of aliphatic or aromatic amines. While all synthesized polymers presented high thermal stability via thermogravimetric analysis, the glass-transition temperature and crystallinity were shown to be highly tied to the structure of the backbone between repeating sulfamide units through differential scanning calorimetry and powder X-ray diffraction. Careful analysis via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and X-ray crystallography also revealed the formation of macrocyclic oligomers during the polymerization of one AB monomer. Finally, two protocols were developed to efficiently degrade all synthesized polysulfamides through either chemical recycling for polymers derived from aromatic amines or oxidative upcycling for those based on aliphatic amines.