Polyoxazolines (PAOx)

Properties and Applications

Polyoxazolines are amorphous to semicrystalline polymers that have been known for over 40 years. This class of polymers is produced by cationic ring-opening polymerization (CROP) of 2-oxazolines. More than a hundred different 2-oxazoline polymers have been reported in the literature to date.1 Their properties range from rubbery and soft with glass transition temperatures well below room temperature to hard and brittle with melting/softening points well above 200°C.1 Their solubility in solvent and water depends on the substituent next to the carbonyl group. Those with small side groups are strongly hydrophilic and water-soluble whereas those with long hydrocarbon side-chains are hydrophobic and water-insoluble.

Many PAOx are highly biocompatible2 and have been intensively studied as materials for biomedical and pharmaceutical applications such as polymer-drug and polymer-protein conjugates, drug delivery micelle carriers, hydrogels, antifouling and antimicrobial devices, and wound healing.1,2 Outside of these applications, oxazoline polymers have found no noteworthy commercial applications.
The monomer oxazoline itself has been used to functionalize acrylic and styrene-acrylic copolymers.3 These reactive resins find uses as polymer crosslinkers and adhesion promotors in numerous water- and solvent-borne products including coatings, paints, inks, and pressure sensitive adhesives.4 They can also be used as compatibilizers in thermoplastics and as binders and surface conditioners in textile products.

Manufacturers

Brand Names

1M. Glassner, M. Vergaelen and R. Hoogenboom, Polym. Int., 67, 32–45 (2018)
2A. Dworak, B. Trzebicka, A. Kowalczuk, C. Tsvetanov, S. Rangelov, Polimery, 59, 1 (2014)
3EPOCROS Brochure: Novel Low toxic Polymer Crosslinker and Adhesion Promoting Agent, Nippon Shokubai Co. 2016
4Oxazolines readily react with carboxyl, thiol and phenol groups but not with alcohols. The reaction with carboxyl groups
proceeds rapidly at elevated temperatures (80-100°C).3