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Ultrasmall Self-Assembly poly(N-isopropylacrylamide-butyl Acrylate) (polyNIPAM-BA) Thermoresponsive Nanoparticles

Anna Baranowska-Korczyc, Emilia Stelmach, Bohdan Paterczyk, Krzysztof Maksymiuk, Agata Michalska

J Colloid Interface Sci. 2019 Apr 15;542:317-324.

PMID: 30763899

Abstract:

Reported poly(N-isopropylacrylamide) (poly(NIPAM)) thermoresponsive systems do not preserve their structure and shape regardless applied temperature. Poly(NIPAM) modified with lipophilic units of butylacrylate (BA) is expected to form spontaneously nanospheres stable at a broad range of temperature. Moreover, it should be possible to introduce solvatochromic dyes to the spheres for optical evaluation of the system and designing thermometers at the nanoscale. In this study, poly(NIPAM-BA) polymer used in nanoprecipitation process formed stable nanospheres, as shown by scanning transmission electron microscopy (STEM), dynamic light scattering (DLS), and zeta potential analysis. As a model compound, Nile Red was introduced to the structures allowing fluorometric investigation and confocal imaging. The nanoparticles were stable in solution both below and above polymer transition temperature. However, as expected for thermoresponsive polymer, the diameter of nanospheres changed from about 30 nm at 10 °C to about 150 nm at 20 °C. For dye loaded spheres this process was coupled with pronounced change in emission. For low temperatures nanostructures existed as ultra-small highly lipophilic particulates, whereas at higher temperatures their diameter and hydrophilicity increased. In consequence the dye was extruded from spheres at low temperatures as a shell layer, this process was fully reversible within the temperatures range from 5 to 30 °C. Freezing of the nanospheres resulted in irreversible change in morphology allowing monitoring of transient sample freezing. Forming poly(NIPAM-BA) spheres loaded with solvatochromic dyes were found as a facile technique for designing optical nanothermometer.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP9003490 Poly(butyl acrylate) solution Poly(butyl acrylate) solution 9003-49-0 Price
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