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Evaluation of the surface free energy of plant surfaces: toward standardizing the procedure.

Fernández V, Khayet M - Front Plant Sci (2015)

Bottom Line: Plant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors.During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials.Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3-Liquids method.

View Article: PubMed Central - PubMed

Affiliation: Forest Genetics and Ecophysiology Research Group, Plant Physiology and Anatomy Unit, School of Forest Engineering, Technical University of Madrid Madrid, Spain.

ABSTRACT
Plant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors. During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials. Contact angle measurement of different liquids is a common tool for characterizing synthetic materials, which is just beginning to be applied to plant surfaces. However, some studies performed with polymers and other materials showed that for the same surface, different surface free energy values may be obtained depending on the number and nature of the test liquids analyzed, materials' properties, and surface free energy calculation methods employed. For 3 rough and 3 rather smooth plant materials, we calculated their surface free energy using 2 or 3 test liquids and 3 different calculation methods. Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3-Liquids method. Given the major chemical and structural diversity of plant surfaces, it is concluded that 3 different liquids must be considered for characterizing materials of unknown physico-chemical properties, which may significantly differ in terms of polar and dispersive interactions. Since there are just few surface free energy data of plant surfaces with the aim of standardizing the calculation procedure and interpretation of the results among for instance, different species, organs, or phenological states, we suggest the use of 3 liquids and the mean surface tension values provided in this study.

No MeSH data available.


Related in: MedlinePlus

Plant surfaces analysed. (A) Upper leaf side of red ironbark (major micro- and nano roughness), (B) upper leaf side of juvenile blue gum (major micro- and nano roughness conferred by wax nano-tubes), (C) lower leaf side of holm oak (great micro-roughness conferred by the hairs/trichomes), (D) upper leaf side of rubber tree (rather smooth), (E) upper leaf side of Chilean myrtle (rather smooth), and (F) pepper fruit surface (rather smooth).
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Figure 1: Plant surfaces analysed. (A) Upper leaf side of red ironbark (major micro- and nano roughness), (B) upper leaf side of juvenile blue gum (major micro- and nano roughness conferred by wax nano-tubes), (C) lower leaf side of holm oak (great micro-roughness conferred by the hairs/trichomes), (D) upper leaf side of rubber tree (rather smooth), (E) upper leaf side of Chilean myrtle (rather smooth), and (F) pepper fruit surface (rather smooth).

Mentions: The adaxial leaf surface of red ironbark and blue gum eucalypt, and abaxial leaf side of holm oak were found to have a high degree of roughness (Figures 1A–C). This is due to the presence of milimetric trichomes on to the lower leaf side of holm-oak, wax nano-tubes on the surface of blue gum eucalypt leaves, and wax platelets and a complex micro-topography provided by the epidermal cells of red ironbark leaves. By contrast, the upper leaf surface of rubber tree and Chilean myrtle is rather flat alike that of pepper fruit (Figures 1D–F).


Evaluation of the surface free energy of plant surfaces: toward standardizing the procedure.

Fernández V, Khayet M - Front Plant Sci (2015)

Plant surfaces analysed. (A) Upper leaf side of red ironbark (major micro- and nano roughness), (B) upper leaf side of juvenile blue gum (major micro- and nano roughness conferred by wax nano-tubes), (C) lower leaf side of holm oak (great micro-roughness conferred by the hairs/trichomes), (D) upper leaf side of rubber tree (rather smooth), (E) upper leaf side of Chilean myrtle (rather smooth), and (F) pepper fruit surface (rather smooth).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493370&req=5

Figure 1: Plant surfaces analysed. (A) Upper leaf side of red ironbark (major micro- and nano roughness), (B) upper leaf side of juvenile blue gum (major micro- and nano roughness conferred by wax nano-tubes), (C) lower leaf side of holm oak (great micro-roughness conferred by the hairs/trichomes), (D) upper leaf side of rubber tree (rather smooth), (E) upper leaf side of Chilean myrtle (rather smooth), and (F) pepper fruit surface (rather smooth).
Mentions: The adaxial leaf surface of red ironbark and blue gum eucalypt, and abaxial leaf side of holm oak were found to have a high degree of roughness (Figures 1A–C). This is due to the presence of milimetric trichomes on to the lower leaf side of holm-oak, wax nano-tubes on the surface of blue gum eucalypt leaves, and wax platelets and a complex micro-topography provided by the epidermal cells of red ironbark leaves. By contrast, the upper leaf surface of rubber tree and Chilean myrtle is rather flat alike that of pepper fruit (Figures 1D–F).

Bottom Line: Plant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors.During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials.Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3-Liquids method.

View Article: PubMed Central - PubMed

Affiliation: Forest Genetics and Ecophysiology Research Group, Plant Physiology and Anatomy Unit, School of Forest Engineering, Technical University of Madrid Madrid, Spain.

ABSTRACT
Plant surfaces have been found to have a major chemical and physical heterogeneity and play a key protecting role against multiple stress factors. During the last decade, there is a raising interest in examining plant surface properties for the development of biomimetic materials. Contact angle measurement of different liquids is a common tool for characterizing synthetic materials, which is just beginning to be applied to plant surfaces. However, some studies performed with polymers and other materials showed that for the same surface, different surface free energy values may be obtained depending on the number and nature of the test liquids analyzed, materials' properties, and surface free energy calculation methods employed. For 3 rough and 3 rather smooth plant materials, we calculated their surface free energy using 2 or 3 test liquids and 3 different calculation methods. Regardless of the degree of surface roughness, the methods based on 2 test liquids often led to the under- or over-estimation of surface free energies as compared to the results derived from the 3-Liquids method. Given the major chemical and structural diversity of plant surfaces, it is concluded that 3 different liquids must be considered for characterizing materials of unknown physico-chemical properties, which may significantly differ in terms of polar and dispersive interactions. Since there are just few surface free energy data of plant surfaces with the aim of standardizing the calculation procedure and interpretation of the results among for instance, different species, organs, or phenological states, we suggest the use of 3 liquids and the mean surface tension values provided in this study.

No MeSH data available.


Related in: MedlinePlus