Functional polymer based on 2,6-diaminopyridine with tunable UCST behaviour in water/alcohol mixture

Thermoresponsive polymers are of great importance in numerous applications such as bioseparation, drug delivery, diagnostic and microfluidic applications. Only few thermoresponsive polymers that present an upper critical solution temperature (UCST), i.e. phase separate from solution upon cooling, in a relevant temperature range and green solvents such as water or ethanol have been reported. Indeed, polymers with UCST behavior below 60°C in alcohol or water/alcohol mixtures are extremely promising for the preparation of smart materials for sensing. In this work two novel functional polymers of based on a 2,6-diaminopyridine motif were synthesized by free radical polymerization. Their UCST-type transition temperature is tunable by varying either their concentration in solution or the type of solvent. Insights into this phenomenon will be given based on turbidimetry and temperature dependent dynamic light scattering