0
Institute for Micromanufacturing
                  Louisiana Tech University




Clay Nanotubes for Controlled Release
   ...
Carbon Nanotubes versus Halloysite




Parameter                     Halloysite            CarbonTubes
Diameter / length  ...
Schematic Representation

                                                          15 nm


                              ...
Potential Applications of
                            pp
                 Halloysite as Nanocontainer

1) Paint with anti-...
Halloysite Mi
H ll it Microscopy images
                   i
Halloysite




                        0.5
DV [10-3 cm3*Å-1*g-1]




                        0.4
                *




   ...
Halloysite - biocompatible “green” nanoparticles




                                          CLSM images of HNTs
       ...
Halloysite nanotubes in paint
                 H ll   it      t b i      i t




Protective chemicals (corrosion inhibitor...
General procedure for preparation of
    halloysite-paint composite
Halloysite-Paint composite
                                       y              p
                                  tensi...
Paint-halloysite composite
           y        p
surface properties
                       100

                        90...
Paint Resistance to rapid
                      p
      deformation

                             7
                      ...
Paint dh i
P i t adhesion test
               t t
Adhesion t t on 2024 Al
Adh i    test


                      Epoxy




                     Polyuret
                    ...
Controlling Release Rates



• Release rate may be controlled by geometry of
  halloysite nanotubes (tubes with smaller in...
Benzotriazole release
                              characteristics

               100
                90
               ...
Formation of stoppers at tube
                pp
endings
TEM with elemental analysis
  Free
Halloysite



                             Overlap mapping image      Oxygen mapping
  ...
Halloysite Tubes as Nanocontainers for Anticorrosion Coating
                                                  with Benzot...
Anticorrosion coating by using
                                              g y     g
                                   ...
Corrosion inhibition kinetics
                                                       C     i   i hibiti ki ti

           ...
Anticorrosion coating by using
                                    g y     g
                         halloysite

        ...
Encapsulation of nanotubes byy
                                              LbL assembly of polyelectrolytes

           ...
Conclusions
                         C   l i

1.   The capability of naturally occurring clay nanotubes as a
     nanocont...
Acknowledgements
             A k   l d     t


                            Andre Zeitoun, Applied Minerals,
            ...
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Western Coating Symp10 09 [Compatibility Mode]

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Paper Highlighting certain applications of Halloysite Clay.

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Transcript of "Western Coating Symp10 09 [Compatibility Mode]"

  1. 1. Institute for Micromanufacturing Louisiana Tech University Clay Nanotubes for Controlled Release y of Active Agents Yuri Lvov and Elshad Abdullayev Halloysite tubules clay of 50 nm diameter H ll it t b l l f di t with 15 nm lumen, and ca 1000 nm length. Tiny tubular containers to keep loaded chemicals for a long time and release them in coating defects 29th Biennial Western Coating Symposium, Las Vegas, NM, October 25-28, 2009
  2. 2. Carbon Nanotubes versus Halloysite Parameter Halloysite CarbonTubes Diameter / length 50 / 1000 nm 2 / 1000 nm Inner Lumen Diameter 15 nm 1 nm Biocompatibility Biocompatible Poisonous Price / availability ca $6 per kg / tons $200,000 per kg / grams Patents 8-10 ca 300 Publications P bli ti 26 and 12 of th d f them – ours ca 50 000 50,000 Researchers / companies Applied Minerals Inc., hundreds companies LaTech, China and labs
  3. 3. Schematic Representation 15 nm 0.2 -1.0 μm 7Å Oxygen 7Å OH group Dragon Mine UT Mine, Aluminium Applied Minerals, Inc Silicon End on View of Kaolinite / Halloysite Halloysite occurs i nature as h d t d mineral th t h H ll it in t hydrated i the formula of Al2Si2O5(OH)4.2H2O l that has th f l f which is similar to kaolinite except for the presence of an additional water monolayer between the adjacent layers. It forms by kaolinite layer rolling due to the action of hydrothermal processes.
  4. 4. Potential Applications of pp Halloysite as Nanocontainer 1) Paint with anti-fouling properties where marine biocide was loaded. Delivery of herbicides, insecticides, fungicides and anti-microbials 2) Release of anticorrosion agents 3) Plastic fillers 4) Specific ion adsorbent, hydrogen storage ) p , y g g 5) Drug sustained release (cosmetics), fertilizers, food additives, fragrance 6) Templating nanoparticle synthesis 7) Use in advanced ceramic materials bio-implants materials, bio implants 8) Catalytic materials and molecular sieves.
  5. 5. Halloysite Mi H ll it Microscopy images i
  6. 6. Halloysite 0.5 DV [10-3 cm3*Å-1*g-1] 0.4 * 0.3 0.2 0.1 0.0 0 50 100 150 200 Pore diameter [nm] Pore size distribution of halloysite nanotubes obtained from N2 adsorption measurements analyzed with BET Zeta potential for silica (blue) , halloysite (middle model curve) and alumina (red) nanoparticles
  7. 7. Halloysite - biocompatible “green” nanoparticles CLSM images of HNTs (functionalised by APTES) intracellular uptake by HeLa cells. (Up) Hoechst-fluorescence of nuclei (blue) (left) and FITC- fluorescence (green) of (g ) HNTs+APTES (right). (down) Transmission image of HeLa cells and (down) FITC Fluorescence HNTs+APTES and HeLa nuclei (blue) overlayed images (right). Applied Minerals Inc Dragon Mine Inc., Making halloysite tube fluorescent with aminopropyl triethoxysilane-FITC Trypan Blue test of HNTs in HeLa (and MCF-7 tissue cells. % MCF 7 ti ll Cell Viability vs HNTs concentration for 24- 48-72 hours. It is much less toxic than usual table salt - NaCl ( which kills cells at concentration of 5 µg/ml )
  8. 8. Halloysite nanotubes in paint H ll it t b i i t Protective chemicals (corrosion inhibitors, antifouling agents) slowly release from the halloysite t b h ll it tubes when cracks occurred. h k d
  9. 9. General procedure for preparation of halloysite-paint composite
  10. 10. Halloysite-Paint composite y p tensile properties 2.5 3 0% halloysite 1% halloysite 2 2% halloysite 2.5 a) 5% halloysite 0% Stress (MPa Stress (MPa) 10% halloysite 2 1% 1.5 30% halloysite 2% 1.5 5% 1 10% 1 0.5 0.5 0 0 0 5 10 15 20 25 30 0 10 20 30 40 50 Strain (%) Strain (%) Halloysite is readily mixed with a variety of metal protective coatings, which is an important advantage of this material. Above pictures describe stress- strain characteristics of halloysite-paint comopsites with different halloysite halloysite paint concentration. Epoxy (left) and Polyurethane (right) paints were used in this experiment.
  11. 11. Paint-halloysite composite y p surface properties 100 90 P ol yurethane C o n ta ct a n g le 80 P ol yepoxy 70 60 50 40 0 2 4 6 8 10 H aloysi concentrati (w t% ) l te on Water contact angles on paint halloysite nanocomposite surfaces
  12. 12. Paint Resistance to rapid p deformation 7 A366 Fe alloy 6 2024 Al alloy Deformation energy (J) 5 e 4 3 D 2 1 0 0 2 4 6 8 10 12 Halloysite concentration (%)
  13. 13. Paint dh i P i t adhesion test t t
  14. 14. Adhesion t t on 2024 Al Adh i test Epoxy Polyuret hane
  15. 15. Controlling Release Rates • Release rate may be controlled by geometry of halloysite nanotubes (tubes with smaller internal diameters provide longer release) • Rate can also be controlled through: 1) formation of stoppers at tube endings 2) encapsulation of nanotubes by layer-by-layer (LbL) nanoassembly of polyelectrolytes
  16. 16. Benzotriazole release characteristics 100 90 80 70 BTA release from halloysite R elease (%) BTA diffusion into water 60 50 40 30 20 10 0 100 0 10 20 30 40 50 90 Time (hrs) 80 R elease (%) 70 60 50 40 30 20 10 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Time (hrs)
  17. 17. Formation of stoppers at tube pp endings
  18. 18. TEM with elemental analysis Free Halloysite Overlap mapping image Oxygen mapping Nitrogen mapping g pp g (Nitrogen and Oxygen) (Nit dO ) 0.2m 0.2m
  19. 19. Halloysite Tubes as Nanocontainers for Anticorrosion Coating with Benzotriazole 100 Blank 0.04 0 04 mM 80 0.4 mM R ele as e (% ) 2.0 mM 60 4.0 mM 8.0 mM 40 20.0 mM Tube stopper formation 20 0 0 120 240 360 480 Time (min) Benzotriazole release with different stoppers at the tube ends CCD images (top) and current density maps (bottom) of Al coated with sol gel layer immersed in sol-gel 0.1 NaCl after 0, 4.5 and 10 h; left- without halloysite, and right -doped with benzotriazole loaded halloysite nanotubes
  20. 20. Anticorrosion coating by using g y g halloysite Two copper strips were painted with oil based blue paint (ECS- 34 powder, blue, produced by Tru-Test Tru Test manufacturing company) for corrosion resistance testing. Halloysite nanotubes loaded with benzotriazole was mixed with paint before painting sample (A). Both of the strips were artificially scratched and exposed to highly corrosive media containing 24 g/l NaCl, 3.8 g/l CaCl2, and 2 g/l Na2SO4 for 10 days. Images show that coated with only paint is covered with green rust while no evidences of rust is visible for the sample that is covered with the paint containing halloysite. Corrosive media, that samples were exposed to for 10 p p g y , p p days, was also analyzed for Cu (II) content. Copper in corrosive media were detected by UV-Vis spectrophotometer, and 120 ppm of copper ion was observed in the media where sample (B) was exposed while no copper was detected in the media of sample (A).
  21. 21. Corrosion inhibition kinetics C i i hibiti ki ti 0.7 16 centration (ppm) B en z o tria o le m ass (  g ) 0.6 ( 12 0.5 0.4 Fresh water 8 0.3 Usual paint coating az Salty water Cu( II) conc Paint h ll P i t - halloysite composite it it 0.2 4 0.1 0 C 0 0 3 6 9 12 15 18 21 0 5 10 15 20 25 30 35 Time (hrs) Time (days) Kinetics of BTA deposition on Cu surface Kinetics of corrosion process, studied by studied by QCM. Process follows 1st tracking f th C (II) t ki of the Cu(II) concentration in t ti i order kinetics with the constants of 0.012 corrosive media and 0.0033 for fresh and salty waters respectively
  22. 22. Anticorrosion coating by using g y g halloysite Copper strips were painted with polyurethane paint from top side and epoxy paint from the back side and artificially scratched. Strip at (a) painted with usual paint while strip at (b) had halloysite loaded with benzotriazole admixed with epoxy paint. Strips were exposed to water containing 30 g/l NaCl. (a) (b) (a) After 9 days of exposure and (b) after 35 days of exposure into corrosive liquid.
  23. 23. Encapsulation of nanotubes byy LbL assembly of polyelectrolytes 50 PEI 7 PEI PEI 40 PAA 6 Layer thicknes s (nm) 30 5 mV) 20 Sample 1 Zeta potential (m 10 Sample 2 4 PEI Sample 3 0 PAA Sample 4 3 1 2 3 4 5 6 -10 Sample 5 2 -20 Sample 6 PAA -30 1 PEI -40 PAA PAA 0 PEI PAA -50 1 2 3 4 5 6 7 Number of layers No of layer Alteration of surface charge during LbL assembly as well as deposition of 7 nm SiO2 nanoparticles on halloysite surface clearly indicates that the assembly was performed successfully. An average thickness of PEI/PAA bilayer is 2.2 nm. PEI - poly(ethyleneimine), PAA - poly(acrylic acid) 100 nm
  24. 24. Conclusions C l i 1. The capability of naturally occurring clay nanotubes as a nanocontainers for protective agents (e.g., corrosion inhibitors) p g ( g, ) was demonstrated. Inhibitors may be kept in such nanocontainers for long time and released in the defect points within hours. Efficiency of paint coating with benzotriazole halloysite was demonstrated for copper, aluminum, and iron. y pp , , 2. Once loaded with protective agents, halloysite nanotubes can be modified by formation of stoppers at tube endings to extend inhibitor release rate. 3. 3 Halloysite nanotubes are readily mixed with variety of polymers and paints. Physical properties of halloysite / paint composites were improved.
  25. 25. Acknowledgements A k l d t  Andre Zeitoun, Applied Minerals, Inc, NY  H. Möhwald, D. Shchukin, Max Planck Inst, Potsdam, Germany  K. Ariga, National Inst Materials Science, Tsukuba, Japan The work was supported by Louisiana Board of Regents ITRS-2009 grants
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