Picture of industrial chimneys polluting horizon

Open Access research shaping international environmental governance...

Strathprints makes available scholarly Open Access content exploring environmental law and governance, in particular the work of the Strathclyde Centre for Environmental Law & Governance (SCELG) based within the School of Law.

SCELG aims to improve understanding of the trends, challenges and potential solutions across different interconnected areas of environmental law, including capacity-building for sustainable management of biodiversity, oceans, lands and freshwater, as well as for the fight against climate change. The intersection of international, regional, national and local levels of environmental governance, including the customary laws of indigenous peoples and local communities, and legal developments by private actors, is also a signifcant research specialism.

Explore Open Access research by SCELG or the School of Law. Or explore all of Strathclyde's Open Access research...

Nanoscale contact mechanics of biocompatible polyzwitterionic brushes

Zhang, Zhenyu and Morse, Andrew J. and Armes, S. P. and Lewis, A. L. and Geoghegan, Mark and Leggett, Graham J. (2013) Nanoscale contact mechanics of biocompatible polyzwitterionic brushes. Langmuir, 29 (34). pp. 10684-10692. ISSN 0743-7463

Full text not available in this repository. Request a copy from the Strathclyde author


Friction force microscopy has been used to demonstrate that biocompatible, lubricious poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC) brushes exhibit different frictional properties depending on the medium (methanol, ethanol, 2-propanol, and water; the latter also with different quantities of added salt). The chemical functionalization of the probe (amine-, carboxylic acid-, and methyl-terminated probes were used) is not as important as the medium in determining the contact mechanics. For solvents such as methanol, where the adhesion between AFM probe and PMPC brushes is negligible, a linear friction–load relationship is observed. In contrast, the friction–load plot is nonlinear in ethanol or water, media in which stronger adhesion is measured. For ethanol, the data indicate Johnson–Kendall–Roberts (JKR) mechanics, whereas the Derjaguin–Muller–Toporov (DMT) model provided a good fit for the data acquired in water. Contact mechanics on zwitterionic PMPC brushes immersed in aqueous solutions of varying ionic strength followed the same trend, with high adhesion energies being correlated with a nonlinear friction–load relationship. These results can be rationalized by treating the friction force as the sum of a load-dependent term, attributed to molecular plowing, and an area-dependent shear term. In a good solvent for PMPC such as methanol, the shear term is negligible and the sliding interaction is dominated by molecular plowing. However, the adhesion energy is significantly larger in water and ethanol and the shear term is no longer negligible.