TY - JOUR
T1 - Anisotropic surface energetics and wettability of macroscopic form I paracetamol crystals
AU - Heng, Jerry Y.Y.
AU - Bismarck, Alexander
AU - Lee, Adam F.
AU - Wilson, Karen
AU - Williams, Daryl R.
PY - 2006/3/14
Y1 - 2006/3/14
N2 - Advancing (θA) and receding (θR) contact angles
were measured with several probe liquids on the external facets (201),
(001), (011), and (110) of macroscopic form I paracetamol crystals as
well as the cleaved (internal) facet (010). For the external crystal
facets, dispersive surface energies γd calculated from the contact angles were found to be similar (34 ± 1 mJ/m2),
while the polar components varied significantly. Cleaving the crystals
exposed a more apolar (010) surface with very different surface
properties, including γd = 45 ± 1 mJ/m2. The relative surface polarity (γp/γ)
of the facets in decreasing order was (001) > (011) > (201) >
(110) > (010), which agreed with the fraction of exposed polar
hydroxyl groups as determined from C and O 1s X-ray photoelectron
spectroscopy (XPS) spectra, and could be correlated with the number of
non-hydrogen-bonded hydroxyl groups per unit area present for each
crystal facet, based on the known crystal structures. In conclusion, all
facets of form I paracetamol crystals examined exhibited anisotropic
wetting behavior and surface energetics that correlated to the presence
of surface hydroxyl groups.
AB - Advancing (θA) and receding (θR) contact angles
were measured with several probe liquids on the external facets (201),
(001), (011), and (110) of macroscopic form I paracetamol crystals as
well as the cleaved (internal) facet (010). For the external crystal
facets, dispersive surface energies γd calculated from the contact angles were found to be similar (34 ± 1 mJ/m2),
while the polar components varied significantly. Cleaving the crystals
exposed a more apolar (010) surface with very different surface
properties, including γd = 45 ± 1 mJ/m2. The relative surface polarity (γp/γ)
of the facets in decreasing order was (001) > (011) > (201) >
(110) > (010), which agreed with the fraction of exposed polar
hydroxyl groups as determined from C and O 1s X-ray photoelectron
spectroscopy (XPS) spectra, and could be correlated with the number of
non-hydrogen-bonded hydroxyl groups per unit area present for each
crystal facet, based on the known crystal structures. In conclusion, all
facets of form I paracetamol crystals examined exhibited anisotropic
wetting behavior and surface energetics that correlated to the presence
of surface hydroxyl groups.
UR - http://www.scopus.com/inward/record.url?scp=33645522818&partnerID=8YFLogxK
UR - http://pubs.acs.org/doi/abs/10.1021/la0532407
U2 - 10.1021/la0532407
DO - 10.1021/la0532407
M3 - Article
AN - SCOPUS:33645522818
SN - 0743-7463
VL - 22
SP - 2760
EP - 2769
JO - Langmuir
JF - Langmuir
IS - 6
ER -