Influence of molecular weight on PNIPAM brush modified colloidal silica particles
(2019) In Soft Matter 15(1). p.55-64- Abstract
- The effect of molecular weight and temperature on the phase transition and internal structure of poly(N-isopropylacrylamide) brush modified colloidal silica particles was investigated using dynamic light scattering (DLS) and small angle neutron scattering (SANS) between 15 and 45 °C. Dry particle analysis utilising transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) all confirmed the thickness of the polymer brush shell increased as a function of polymerisation time. Hydrodynamic diameter and electrophoretic mobility results revealed that the brush modified particles transitioned from swollen shells to a collapsed conformation between 15 and 35 °C. The dispersions were... (More)
- The effect of molecular weight and temperature on the phase transition and internal structure of poly(N-isopropylacrylamide) brush modified colloidal silica particles was investigated using dynamic light scattering (DLS) and small angle neutron scattering (SANS) between 15 and 45 °C. Dry particle analysis utilising transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) all confirmed the thickness of the polymer brush shell increased as a function of polymerisation time. Hydrodynamic diameter and electrophoretic mobility results revealed that the brush modified particles transitioned from swollen shells to a collapsed conformation between 15 and 35 °C. The dispersions were electrosterically stabilised over the entire temperature range investigated, with minimal thermal hysteresis recorded. Modelling of the hydrodynamic diameter enabled the calculation of a lower critical solution temperature (LCST) which increased as a function of brush thickness. The internal structure determined via SANS showed a swollen brush at low temperatures (18 and 25 °C) which decayed radially away from the substrate, while a collapsed block-like conformation with 60% polymer volume fraction was present at 40 °C. Radial phase separation was evident at intermediate temperatures (30 and 32.5 °C) with the lower molecular weight sample having a greater volume fraction of polymer in the dense inner region at these temperatures. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/e75f8577-731d-4af4-bf55-fd87430574d9
- author
- Humphreys, Ben A. LU ; Prescott, Stuart W. ; Murdoch, Timothy J. ; Nelson, Andrew ; Gilbert, Elliot P. ; Webber, Grant B. and Wanless, Erica J.
- publishing date
- 2019
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Soft Matter
- volume
- 15
- issue
- 1
- pages
- 10 pages
- publisher
- Royal Society of Chemistry
- external identifiers
-
- scopus:85058887479
- ISSN
- 1744-6848
- DOI
- 10.1039/C8SM01824C
- language
- English
- LU publication?
- no
- id
- e75f8577-731d-4af4-bf55-fd87430574d9
- date added to LUP
- 2022-04-01 21:06:24
- date last changed
- 2022-06-06 04:01:40
@article{e75f8577-731d-4af4-bf55-fd87430574d9,
abstract = {{The effect of molecular weight and temperature on the phase transition and internal structure of poly(N-isopropylacrylamide) brush modified colloidal silica particles was investigated using dynamic light scattering (DLS) and small angle neutron scattering (SANS) between 15 and 45 °C. Dry particle analysis utilising transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) all confirmed the thickness of the polymer brush shell increased as a function of polymerisation time. Hydrodynamic diameter and electrophoretic mobility results revealed that the brush modified particles transitioned from swollen shells to a collapsed conformation between 15 and 35 °C. The dispersions were electrosterically stabilised over the entire temperature range investigated, with minimal thermal hysteresis recorded. Modelling of the hydrodynamic diameter enabled the calculation of a lower critical solution temperature (LCST) which increased as a function of brush thickness. The internal structure determined via SANS showed a swollen brush at low temperatures (18 and 25 °C) which decayed radially away from the substrate, while a collapsed block-like conformation with 60% polymer volume fraction was present at 40 °C. Radial phase separation was evident at intermediate temperatures (30 and 32.5 °C) with the lower molecular weight sample having a greater volume fraction of polymer in the dense inner region at these temperatures.}},
author = {{Humphreys, Ben A. and Prescott, Stuart W. and Murdoch, Timothy J. and Nelson, Andrew and Gilbert, Elliot P. and Webber, Grant B. and Wanless, Erica J.}},
issn = {{1744-6848}},
language = {{eng}},
number = {{1}},
pages = {{55--64}},
publisher = {{Royal Society of Chemistry}},
series = {{Soft Matter}},
title = {{Influence of molecular weight on PNIPAM brush modified colloidal silica particles}},
url = {{http://dx.doi.org/10.1039/C8SM01824C}},
doi = {{10.1039/C8SM01824C}},
volume = {{15}},
year = {{2019}},
}