Small-Angle Neutron Scattering Study of Cyclic Poly(ethylene
glycol) Adsorption on Colloidal Particles
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Abstract
The adsorptions of cyclic PEG and
linear PEG on colloidal silica
particles were compared. Their adsorption volume fraction profiles
were generated through model fitting of small-angle neutron scattering
data from the adsorbed polymer layers. The two important parameters
to describe adsorbed polymer layers were discussed in detail. It was
found that the adsorption amounts of cyclic PEGs increased with molecular
weight but were generally higher than their linear counterparts. However,
the root-mean-square layer thickness, δ<sub>rms</sub>, of adsorbed
cyclic PEGs was found to decrease with molecular weight, opposing
adsorbed linear PEGs and the theoretic prediction based on SF model.
This disagreement was ascribed to the topological restriction of cyclic
polymer at low molecular weight. An illustrated structural evolution
with molecular weight for adsorbed polymer at interface was tentatively
proposed based on the observations of this study