Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- 2,6-diaminopyridine (3) (entfernen)
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UCST-type thermoresponsive polymers (i.e. that phase separate from solution upon cooling) present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications, but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and “green” solvents such as water or ethanol.
In this context, acrylamide-based monomers can be very useful building blocks for designing novel non-ionic UCST-type polymers because of their hydrophilic nature (with the appropriate side chain) and propensity to form hydrogen bonds. We will present our latest results on the UCST-type thermoresponsive behaviour of acrylamide- and 2,6-diaminopyridine-based homopolymers and copolymers in water or water/alcohol mixtures, and give some insights about the rational design of UCST polymers relying on H-bonding.
UCST-type thermoresponsive polymers (i.e. that phase separate from solution upon cooling) present a tremendous potential not only in aqueous media where they can be used in drug delivery, diagnostic and microfluidic applications but also in water/alcohol mixtures, where they can be used for instance in sensing systems for alcohol-soluble drugs. However, only a few thermoresponsive polymers have been reported that present an UCST in a relevant temperature range and “green” solvents such as water or ethanol.
In this context, acrylamide-based monomers can be very useful building blocks for designing novel non-ionic UCST-type polymers because of their hydrophilic nature (with the right side chain) and propensity to form hydrogen bonds. We will present our latest results on the UCST-type thermoresponsive behaviour of acrylamide- and 2,6-diaminopyridine-based homopolymers and copolymers in water or water/alcohol mixtures, and give some insights about the rational design of UCST polymers relying on H-bonding.
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.
In this work two novel functional polymers of based on a 2,6-diaminopyridine motif, namely poly(N-(6-aminopyridin-2-yl)acrylamide) (PNAPAAm) and poly(N-(6-acetamidopyridin-2-yl)acrylamide) (PNAcAPAAm), were synthesized by free radical polymerization. The obtained polymers displayed UCST-type reversible thermoresponsive behaviour in water/alcohol mixtures. Insights into this phenomenon will be given based on visual observations, temperature-dependent turbidimetry and dynamic light scattering as well as 1H-NMR measurements. The UCST phase transition behaviour of the polymers was tunable by varying either the concentration of the polymer solution, the nature of the alcohol or the composition of the solvent mixture. The cloud point temperature of PNAcAPAAm was found to decrease with increasing alcohol content (MeOH, EtOH and iPrOH) in water/alcohol mixtures. Past a critical amount of EtOH or iPrOH in water the cloud point temperature of PNAcAPAAm increased by further addition of EtOH or iPrOH. These polymers with UCST behavior below 60°C in water/alcohol mixtures show great promises for the preparation of smart materials for sensing.