| 1. |
- Bodvik, Rasmus, et al.
(author)
-
Temperature-dependent adsorption of cellulose ethers on silica and hydrophobized silica immersed in aqueous polymer solution
- 2011
-
In: RSC ADVANCES. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 1:2, s. 305-314
-
Journal article (peer-reviewed)abstract
- The influence of temperature on adsorption and the adsorbed layer properties of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) were investigated on silica and hydrophobized silica surfaces immersed in aqueous polymer solution. To achieve a concise understanding a quartz crystal microbalance with dissipation, ellipsometry, and atomic force microscopy imaging were employed. These techniques provide complimentary information on the structure, mass and viscoelastic properties of the polymer layers. Adsorption was first allowed at 25 degrees C. Next, the temperature was increased step-wise up to 50 degrees C and then decreased again. This procedure highlights the temperature dependence of the adsorbed material, as well as the hysteresis in the adsorption due to temperature cycling. A change in temperature not only affects the adsorbed amount, but also the properties of the layer as illustrated by measurements of its water content, thickness and viscoelasticity.
|
|
| 2. |
- Bodvik, Rasmus, et al.
(author)
-
Temperature responsive surface layers of modified celluloses
- 2011
-
In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 13:10, s. 4260-4268
-
Journal article (peer-reviewed)abstract
- The temperature-dependent properties of pre-adsorbed layers of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) were investigated on silica and hydrophobized silica surfaces. Three different techniques, quartz crystal microbalance with dissipation monitoring, ellipsometry, and atomic force microscopy imaging, were used, providing complementary and concise information on the structure, mass and viscoelastic properties of the polymer layer. Adsorption was conducted at 25 degrees C, followed by a rinsing step. The properties of such pre-adsorbed layers were determined as a function of temperature in the range 25 degrees C to 50 degrees C. It was found that the layers became more compact with increasing temperature and that this effect was reversible, when decreasing the temperature. The compaction was more prominent for MC, as shown in the AFM images and in the thickness data derived from the QCM analysis. This is consistent with the fact that the phase transition temperature is lower, in the vicinity of 50 degrees C, for MC than for HPMC. The water content of the adsorbed layers was found to be high, even at the highest temperature, 50 degrees C, explored in this investigation.
|
|
