Phototunable Cloud Point Temperatures Stemming from Cyclic Topology: Synthesis and Thermal Phase Transition Behavior of Cyclic Poly(N‐acryloylsarcosine methyl ester)

Abstract

Cyclic polymers possess distinct properties compared with their linear counterparts, such as smaller hydrodynamic volume, lower viscosity, and higher glass‐transition temperature, etc. To explore the impact of the cyclic topology on the thermo‐induced phase transition behavior of poly(N‐acryloylsarcosine methyl ester) (PNASME), the anthracene‐terminated telechelic PNASMEs are synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization of monomer NASME using a bifunctional chain transfer agent (CTA) with two anthryl groups. Subsequently, cyclic PNASMEs are prepared via UV‐induced cyclization under 365 nm UV. There are considerable increases (up to 50 °C) for the cloud point temperatures (Tcps) of cyclic PNASMEs compared with the linear counterparts. In view of the increment, the Tcp of PNASME is tuned by varying the cyclic/linear ratio (the molar ratio between cyclic PNASME and linear PNASME in the product) with different irradiation time.

Macromolecular architectural effects on solution self-assembly of amphiphilic AB-type block copolymers

“…Conversely, other studies have reported that cyclic polymers tend to have a higher cloud point than linear polymers. 122–125 There are two possible reasons. First, this is attributed to hindered intermolecular connectivity at the topological level, resulting in repulsive forces between cyclic polymers.…”

Hybrid Multiblock Copolymers of 2-Oxazoline and Acrylates via Cu-Catalyzed Azide–Alkyne Cycloaddition Step-Growth Mechanism

“…The competing intramolecular click reaction forming the cyclic product can be undesired, and careful reaction optimization would be required. , However, cyclic polymers also have unique physical properties , and similarly minimizing the intermolecular step-growth reaction can be desirable in some cases. For instance, cyclic polymers have lower hydrodynamic volumes, lower intrinsic viscosities, are less susceptible to degradation , and demonstrate different cloud point temperatures to their linear counterparts . Furthermore, they provide a promising biointerface that typically produces a denser and thicker surface film compared to linear equivalents .…”