A Facile Method of Synthesizing Size-controlled Hollow Cyanoacrylate Nanoparticles for Transparent Superhydrophobic/Oleophobic Surfaces

Transcription

1 Electronic Supplementary Material (ESI) for RSC Advances. This journal is The Royal Society of Chemistry 2016 Supplementary Information A Facile Method of Synthesizing Size-controlled Hollow Cyanoacrylate Nanoparticles for Transparent Superhydrophobic/Oleophobic Surfaces Takeshi Matsubayashi, a Mizuki Tenjimbayashi, a Kengo Manabe, a Kyu-Hong Kyung, a Bin Ding b and Seimei Shiratori* a a School of Integrated Design Engineering, Center for Science and Technology for Designing Functions, Graduate School of Science and Technology, Keio University, Hiyoshi, Kohoku-ku, Yokohama, Kanagawa , Japan. shiratori@appi.keio.ac.jp b State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai , China. binding@dhu.edu.cn Fig. S1. Scheme of cyanoacrylate polymerization, wherein cyanoacrylate is polymerized in the presence of a nucleophilic agent (Nu ) such as water.

2 Fig. S2. Cyanoacrylate nanoparticle with not hollow structure. Water ratio is 15 wt.%.

3 Fig. S3. Particle diameter distribution of hollow cyanoacrylate nanoparticles measured by dynamic light scattering in a liquid state. Marked values are the average ± standard deviation.

4 Fig. S4. Scanning electron microscope images showing the change in the hollow cyanoacrylate nanoparticle (HCNP) diameter as the water ratio is varied as (a) 10.0, (b) 15.0, (c) 20.0, (d) 25.0, and (e) 30.0 wt.%. The samples were made by casting the HCNP solution onto glass slides and subsequently drying them.

5 Fig. S5. Particle diameters of hollow cyanoacrylate nanoparticles produced with varying water ratios as measured from scanning electron microscope (SEM) images and dynamic light scattering (DLS). Particle diameters less than 40 nm were not observed in SEM because of the vacuum conditions, though they were detected in the DLS samples.

6 Fig. S6. Scanning electron microscope images of hollow cyanoacrylate nanoparticles with varying water ratios of (a) 8.5, (b) 9.0, and (c) 9.5 wt.%.the network structure gradually approaches particle aggregation, though the particle structure is never completely defined.

7 Fig. S7. Scanning electron microscope images of hollow cyanoacrylate nanoparticles produced with 0.20 g of ethyl alpha cyanoacrylate and varying water ratios of (a) 5.0, (b) 7.0, (c) 10.0, (d) 11.0, (e) 12.0, and (f) 13.0 wt.%.

8 Fig. S8. Scanning electron microscope images of hollow cyanoacrylate nanoparticles produced with 0.30 g of ethyl alpha cyanoacrylate and varying water ratios of (a) 12.0, (b) 13.0, and (c) 14.0 wt.%.

9 Fig. S9. Scanning electron microscope images of superhydrophobic/oleophobic surfaces, exhibiting hollow cyanoacrylate nanoparticles produced with varying water ratios of (a) 5.0, (b) 7.0, (c) 10.0, (d) 15.0, (e) 20.0, (f) 25.0, and (g) 30.0 wt.%. (Insets) Areas of the corresponding image magnified 10.

10 Fig. S10 X-ray photoelectron spectra showing the (a) F1s and (b) N1s peaks measured from the hollow cyanoacrylate nanoparticle-coated surface before (black) and after (red) low surface energy treatment. The nanoparticles were produced with a water ratio of 20.0 wt.%.

11 To obtain a deeper understanding of this new type of nanoparticle-generating mechanism, we conduct a verification experiment. First, 9.0 g of acetone and 1.0 g of water were mixed and ultrasonicated for 10 min to allow the dissolved gas to be completely released from the admixture, whereupon 0.1 g of ethyl cyanoacrylate (ECA) was dropped into the mixture under ultrasonication. Scanning electron microscope (SEM) observation of this solution (Fig. S10) reveals that particles do not exist stably owing to the absence of the bubbles that likely play the role of the hollow cyanoacrylate nanoparticle (HCNP) core. Moreover, another verification experiment is conducted wherein the ph of the water was adjusted to 2 via dropping HCl into the mixture, after which HCNPs were synthesized in the same manner given in the Experimental section. The SEM image of these synthesized HCNPs is shown in Fig. S11 wherein, though some crystals are observed, no nanoparticles can be seen.

12 Fig. S11. (a) Scanning electron microscope image of hollow cyanoacrylate nanoparticles in the verification experiment that removes the gas bubbles prior to nanoparticle synthesis, wherein no stable nanoparticles are detected because of the absence of gas cores. (b) Magnified image of same area in (a).

13 Figure S12. (a) Hollow cyanoacrylate nanoparticles are not observed in the scanning electron microscope images when the ph of the water was adjusted to 2. (b) Magnified image of area shown in (a).

14 Figure S13. A picture of two glass slides (bare glass and HCNP coated superhydrophobic/oleophobic glass) onto the display of smartphone after touched by a real finger.