Thermo-responsive cellulose-based architectures: tailoring LCST using poly(ethylene glycol) methacrylates

Abstract

There is a growing interest in designing advanced macromolecular architectures applicable for instance in drug delivery systems. Employing cellulose in these systems is particularly favorable due to attractive properties such as biocompatibility and low price. Additionally, thermo-responsive polymers of poly(ethylene glycol) methacrylates are promising in this field owing to their biocompatibility and non-toxicity. In the present study, amphiphilic thermo-responsive homo- and copolymers of oligo(ethylene glycol) methyl ether methacrylate (OEGMA₃₀₀) and di(ethylene glycol) methyl ether methacrylate (DEGMA) were synthesized via ARGET ATRP. Both linear copolymers of DEGMA/OEGMA₃₀₀ as well as comb architectures with copolymers of DEGMA/OEGMA₃₀₀ grafted from hydroxypropyl cellulose were produced. The lower critical solution temperature of the linear copolymers was readily tailored by altering the monomer feed ratio. The grafting of the thermo-responsive polymers from hydroxypropyl cellulose resulted in a consistent decrease of the lower critical solution temperature compared to the linear analogues; however, interestingly the ability to tune the transition temperature remained. Moreover, the amphiphilic comb architectures formed polymeric micelles with low critical micelle concentrations. Consequently, these advanced architectures combine the favorable properties of hydroxypropyl cellulose with the interesting thermo-responsive and stealth properties of poly(ethylene glycol) methacrylates, and may, therefore, find potential applications in biomedicine.