Document Type

Article

Publication Date

4-15-2008

Publication Title

Journal of Polymer Science: Part B: Polymer Physics

Abstract

The structure and dynamics of crosslinked nanoparticles (microgels) made out of hydroxypropylcellulose (HPC) polymer chains were studied using dynamic light scattering spectroscopy. The microgel light scattering spectra were found to be highly nonexponential requiring a spectral time moment analysis in which the spectra were fit to a sum of stretched exponentials. Each term offers three parameters for analysis and represents a single spectral mode. At room temperature microgel spectra reveal three modes. Two faster modes are almost diffusive and correspond to apparent sizes of 25 and 450–650 nm. The slowest mode is independent of scattering angle and is reminiscent of the slow polymer mode observed in identical non-crosslinked polymer solutions. When solution temperature is varied from 23 to 45°C and back, the microgel undergoes a reversible volume phase transition between 40 and 45°C. According to the time-moment analysis, above the transition temperature two faster modes collapse into one with apparent hydrodynamic radius of 100–150 nm, while the slow mode remains largely unchanged.

DOI

10.1002/polb.21406

Version

Postprint

Volume

46

Issue

8

Included in

Physics Commons

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