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Methods for evaluating leaf surface free energy and polarity having accounted for surface roughness
Author(s) -
Nairn Justin J,
Forster W Alison
Publication year - 2017
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.4551
Subject(s) - wetting , polarity (international relations) , surface roughness , contact angle , surface energy , surface finish , agrochemical , surface tension , materials science , biological system , nanotechnology , chemical physics , chemistry , composite material , thermodynamics , biology , physics , ecology , biochemistry , cell , agriculture
Abstract BACKGROUND Leaf surfaces can have similar wettability, while their roughness and polarity may be very different. This may affect agrochemical bioefficacy, hence there is a need to characterise leaf surface polarity and roughness separately. This paper reviews established surface evaluation techniques and then uses a comprehensive dataset of static contact angles (12 chemical solutions on 15 different species) to compare and contrast them for their ability to characterise leaf surface polarity in isolation from roughness. RESULTS Many techniques were severely limited when applied to leaf surfaces. A failing of the surface free energy ( SFE ) concept is that both physical and chemical properties affect the SFE . Additionally, whilst the leaf surface chemistry does not change, the SFE values generated are dependent on the chemical properties of the probe solution employed. CONCLUSIONS The wetting tension–dielectric ( WTD ) method stands out due to its ability to isolate and quantify leaf surface roughness and polarity. A novel ( WTD ) roughness correction factor is proposed to improve SFE determination. The strong correlation between leaf polarity and leaf wettability for polar solutions (such as water) makes the WTD method a valuable tool for the evaluation of leaf surface‐droplet behaviour and the advancement of agrochemical spray formulation technologies. © 2017 Society of Chemical Industry