zharov lab
sulfonated colloidal films
unmodified silica has no strongly acidic groups, surface sulfonation would: • provide highly acidic groups proton-conductivity conductivity through interconnected nanopores • lead to proton
OH OH OH
O O S O toluene
OH O OH
SO3H H O 2
OH O OH
SO3 + H3O
unmodified SiO2 spheres sulfonated SiO2 spheres
sulfonated lf t d silica ili spheres h can be b self-assembled lf bl d into i t colloidal ll id l films fil Smith, J. J.; Abbaraju, R, R.; Zharov, I. J. Mater. Chem. 2008, accepted.
zharov lab
•
proton conductivity in sulfonated colloidal materials
• pellets - pressed sulfonated spheres • membranes - self self-- assembled sulfonated spheres materials coated with silver, placed between electrodes inside controlled temp/humidity chamber, chamber conductivity is measured using EIS
pellet material
membrane
• •
proton conductivity σ, S/cm (at 100 oC and 98% R R.H.) H)
unmodified
sulfonated
pellet
2.2 x 10-6
7.0 x 10-5
self-assembled selfmembrane
5.0 x 10-6
1.4 x 10-2
pellets: sulfonation increases proton conductivity ~30-fold, it is comparable to that of some porous glasses but quite low membranes: ordering of unmodified spheres increases proton conductivity ~2-fold but for sulfonated spheres this increase is ~2 orders of magnitude Smith, J. J.; Abbaraju, R, R.; Zharov, I. J. Mater. Chem. 2008, accepted.
zharov lab
proton conductive nanonano-frits
novel approach to hybrid proton-conducting membranes: • nano-frit is an inorganic matrix with continuous network of nanopores providing y and water retention mechanical stability • surface-bound polymer brushes with acidic groups provide the proton conductivity • matrix allows to introduce and investigate unprecedented polymer brush architectures • inorganic matrix provides mechanical stability under oxidative conditions and high temperature
Smith, J. J.; Zharov, I. Chem. Mater. 2008, submitted.
zharov lab
proton conductive nanonano-frits Relative Humidity % Relative Humidity, %
100
10
96
TGA
94 92 90 0
100
200
300
400
500
Temperature, oC
600
700
800
unmodified ((purple), ) initiator-modified (green), pSSA modified (red), and pSPM modified (blue) sintered membranes
Proton Conductivity, S ccm‐1
Weight,, %
30
40
50
60
70
80
90
100
1E‐01
98
A 1E‐02
1E‐03
1E‐04
1E‐05
20 15 10 5 0
unmodified
pSPM‐ 7.8%
pSSA‐ 5.8%
pSPM‐ 7.8 wt%‐ 30 °C
pSSA‐ SSA 5.8 wt%‐ 5 8 % 98 °C 98 °C
pSSA‐ SSA 5.8 wt%‐ 5 8 % 30 °C 30 °C
Temperature, °C
Prroton Conducctivity, S cm‐1
25
pSPM‐ 7.8 wt%‐ 98 °C
20
30
Wateer uptake, %
20
1E‐02
40
60
80
100
B
pSPM‐ 7.8 wt% pSSA‐ 5.8 wt% water uptake for sintered membranes 1E‐03 after soaking in water at room temperature for 24 hours. Smith, J. J.; Zharov, I. Chem. Mater. 2008, submitted.
