Fine-tuning the lower critical solution temperature (LCST) of aqueous polymer solutions via simple mixing of polymers with different cloud point temperatures (Tcp's) is an attractive strategy since re-synthesis or copolymerization can be avoided. To obtain controlled intermediate Tcp's via of mixing of two polymers can be referred to as cooperative LCST behavior  It has been suggested that polymers with molecular weight dependent Tcp's are essential to obtain such cooperative behavior based on screening of mixtures poly(N-vinyl pyrrolidone), poly(N-isopropylacrylamide), poly(N-vinylcaprolactam) and poly(oligo(ethyleneglycol) methacrylate).1 However, poly(2-oxazoline)s, as a highly tunable family of thermoresponsive (co)polymers, were not included in this work. In this contribution, we will report a systematical study on the cooperative LCST behavior of copoly(2-oxazoline)s with various Tcp's ranging from 25 to 90 oC. The results suggested that hydrophilicity is a key factor to control the cooperative behavior of poly(2-oxazoline)s as only mxitures of the most hydrophilic copolymers revealed cooperative behavior as shown in the Fig.1. Fig.1 Cooperative behavior of copoly(2-oxazoline)s, P70 represent copoly(2-oxazoline) with Tcp=70 oC, while P90 is copoly(2-oxazoline) with Tcp=90 oC1 N. S. Ieong, M. Hasan, D. J. Phillips, et.al., Polym. Chem., 2012, 3 , 794

Understanding cooperative lower critical solution temperature behavior based on poly(2-oxazoline)s with systematical variations in hydrophobicity

248th National Meeting (2014)

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