Additive Surface Activity
30 Apr 2020



The focus of this study was to establish how polymer matrices with varying degrees of hydrolysis influence the surface properties of small molecule additives.




Controlling the percentage degree of hydrolysis of PVAc to PVA, you can systematically change the polymers matrix from hydrophobic to hydrophilic. The aim of the study was to establish how polymer matrices with varying degrees of hydrolysis influenced the surface properties of small molecule additives. 

The reaction scheme for the hydrolysis of PVAc to PVA  

The additives D-sorbitol, octanoic acid and sodium dodecyl sulfate were used to explore how varying the matrices hydrophobicity effected the surface segregation of these additives, in order to show that segregation in not simple to control and is dependent on multiple factors.​ The surface activity of the additives was investigated using neutron reflectometry, deuterated additives were required to be used for this analysis technique in order to tune the scattering length density of the material. This process, commonly referred to as contrast matching, causes the surface layer of the sample to be highlighted and bulk phase to be hidden. Highlighting the surface layer helps the authors to interpret the data collected from the experiment.

The comparison of deuterated and non-deuterated additives being used in a beamline experiment

The deuteration facility supported this study by providing the deuterated additives D-sorbitol and SDS.

​​The chemical structure of D-sorbitol-d8 and SDS-d25

The authors believe better understanding of these additive-polymer relationships are necessary to allow computational approaches to predict the behaviour of additives in more complex polymer matrices. These predictions would enable advances for industries, by facilitating faster innovations of new products and the avoidance of costly over-engineering and wasted resources. 


Influence of PVAc/PVA hydrolysis on additive surface acti​​​vity

Squillace, O., Fong, R., Shepherd, O., Hind, J., Tellam, J., Steinke, N.J. and Thompson, R.L. (2020). Polymers, 12(1), p.205​