Surface morphological and wetting characterization of the hydrophobic and superhydrophobic leaves of Pistia stratiotes L., Salvinia molesta D.Mitch., Ananas comosus (L.) Merr. and Dyckia platyphylla L.B. Smith for bioinspired oil adsorbent materials

In this paper, the surface morphology and wetting properties towards deionized water and pure oil samples with varying carbon chain lengths of adaxial and abaxial leaf surfaces of Pistia stratiotes L., Salvinia molesta D.Mitch., Ananas comosus (L.) Merr. and Dyckia platyphylla L.B. Smith were characterized. The surface morphological characterization showed that P. stratiotes L. has uniseriate trichomes on adaxial (ad) and abaxial (ab) surface and S. molesta D.Mitch. has multifaceted egg-beater shaped trichomesad and achlorophyllous filamentsab. Both surfaces of the bromeliads, A. comosus (L.) Merr. and D. platyphylla L.B. Smith have peltate scutiform trichomes. Overall, P. stratiotes L. has the greatest trichome density (no.of trichomes/mm2) of ad 36.77 and ab40.10 among A. comosus (L.) Merr. > D. platyphylla L.B. Smith> S. molesta D.Mitch. Contact angle measurement showed that P. stratiotes L. has the best water repellency having (154. 39 +- 3.26)ad > S. molesta D.Mitch. > A. comosus (L.) Merr. > D. platyphylla L.B. Smith and (147.90 +-3.17)ab > A. comosus (L.) Merr. > D. platyphylla L.B. Smith > S. molesta D.Mitch. Lastly, P. stratiotes L. showed the best common pure oil adsorption capacity among the four species. Therefore, the understanding on the fundamental concept on how the leaf surface of P. stratiotes L. adsorbs the oil and reacts in response to various solvents adsorbed on the leaf surface was established.