Thermoresponsive Poly(2-oxazine)s

• Published in: Macromolecular rapid communications. Vol. 33; no. 1; pp. 92 - 96
• Main Authors: Bloksma, Meta M., Paulus, Renzo M., van Kuringen, Huub P. C., van der Woerdt, Friso, Lambermont-Thijs, Hanneke M. L., Schubert, Ulrich S., Hoogenboom, Richard
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 16-01-2012; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Applied sciences; Cationic polymerization; Exact sciences and technology; Isomers; Molecular Structure; Organic polymers; Oxazine; Oxazines - chemistry; Physicochemistry of polymers; poly(2-oxazine); poly(2-oxazoline); Polymerization; Polymers; Polymers - chemical synthesis; Polymers - chemistry; Polyoxazolines; Preparation, kinetics, thermodynamics, mechanism and catalysts; Ring opening polymerization; Solubility; stimuli-responsive polymer; Temperature; thermoresponsive polymer; Substituent effect; Ethyleneimine derivative polymer; Ring opening polymerization; thermoresponsive polymer; Living polymer; poly(2-oxazoline); Cationic polymerization; Experimental study; Cloud point; Preparation; Microwave irradiation; Aqueous solution; poly(2-oxazine); stimuli-responsive polymer
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201100587

The monomers 2‐methyl‐2‐oxazine (MeOZI), 2‐ethyl‐2‐oxazine (EtOZI), and 2‐n‐propyl‐2‐oxazine (nPropOZI) were synthesized and polymerized via the living cationic ring‐opening polymerization (CROP) under microwave‐assisted conditions. pEtOZI and pnPropOZI were found to be thermoresponsive, exhibiting LCST behavior in water and their cloud point temperatures (TCP) are lower than for poly(2‐oxazoline)s with similar side chains. However, comparison of poly(2‐oxazine) and poly(2‐oxazoline)s isomers reveals that poly(2‐oxazine)s are more water soluble, indicating that the side chain has a stronger impact on polymer solubility than the main chain. In conclusion, variations of both the side chains and the main chains of the poly(cyclic imino ether)s resulted in a series of distinct homopolymers with tunable TCP.
Comparison of poly(2‐oxazine) and poly(2‐oxazoline) isomers reveals that poly(2‐oxazine)s are more water soluble, indicating that the side chain has a stronger impact on polymer solubility than the main chain (see image). As such, variations of both side and main chains of poly(cyclic imino ether)s allow accurate tuning of the cloud point temperature in between 94 °C and 11 °C.