Nanoparticle-Doped Polydimethylsiloxane Elastomer Films

Transcription

1 Nanoparticle-Doped Polydimethylsiloxane Elastomer Films DE VIG Jorge Pérez-Juste, Luis M. Liz-Marzán, Isabel Pastoriza-Santos Departamento de Química Física Universidade de Vigo

2 utline DE VIG Some Properties of Polysiloxanes ptical Properties of Gold Nanospheres. Mie Theory Synthesis of Gold Spherical Nanoparticles Synthesis of 2 Modification of 2 surface Formation of Pure PDMS Films Formation of Gold-doped PDMS Films ptical Properties Semiconductor NC-doped PDMS Films Conclusions

3 Physical and Chemical Properties of PDMS DE VIG Polysiloxane R R n * Poly(dimethylsiloxane) H 3 C * n PRPERTY optical electrical mechanical thermal interfacial permeability reactivity toxicity transparent; UV cutoff, 240 nm insulating; breakdown voltage, 2*10 7 V/m elastomeric; tunable Young s modulus, typical value of 750 kpa insulating; thermal conductivity, 0.2 W/(m*K); coefficient of thermal expansion, 310 µm/(m. C) low surface free energy 20 erg/ cm impermeable to liquid water; permeable to gases and nonpolar organic solvents inert; can be oxidized by exposure to a plasma; Bu 4 N + F - ((TBA)F) nontoxic CHARACTERISTIC CNSEQUENCE optical detection from 240 to 1100 nm allows embedded circuits; intentional breakdown to open connections conforms to surfaces; allows actuation by reversible deformation; facilitates release from molds can be used to insulate heated solutions; does not allow dissipation of resistive heating from electrophoretic separation replicas release easily from molds; can be reversibly sealed to materials contains aqueous solutions in channels; allows gas transport through the bulk material; incompatible with many organic solvents unreactive toward most reagents; surface can be etched; can be modified to be hydrophilic and also reactive toward silanes; etching with (TBA)F can alter topography of surfaces can be implanted in vivo; supports mammalian cell growth Whitesides, G. M. et al. Acc.Chem. Res. 2002, 35, 491

4 Composites involving Polysiloxanes DE VIG Reinforced Elastomer by simply blending preformed particles into PDMS chains or in situ preparation of particles normally through sol-gel chemistry. Elastomer-Modified Ceramics. Doping ceramics with elastomers can improve properties, such as the impact strength. Magnetic particles-doped elastomers. Anisotropic reinforcement in elastomers containing magnetic filler particles. Nanotubes-doped elastomers. Reinforcement and increase of the electrical conductivity. Zeolites-doped elastomers. Polymerization inside zeolite cavities.

5 ptical Properties of Gold Nanospheres DE VIG _ nanospheres: single resonance frequency Mie theory for spheres kr«1 C ext = m 24π R ε λ ε" ( ε' + 2ε ) + ε" m 2 2 G. Mie, Ann. Phys. 1908, 25, 337

6 Synthesis of Gold Spheres Citrate Reduction Method Turkevich, J. et al. J. Am. Chem. Soc. 1963, 85, 3317 DE VIG Aqueous HAuCl 4 Solution Aqueous Trisodium Citrate boil 15 min Gold hydrosol ze (~15nm) Coating of Gold Spheres with lica L.M. Liz-Marzán, M. Giersig, P. Mulvaney, J. Chem. Soc., Chem. Commun. 1996, 731

7 Coating of Gold Spheres with lica DE VIG

8 2 surface modification DE VIG TMS 2 + Au TMS NH H 4 Wang W. et al, J. Phys. Chem. B 2003, 107,

9 TMS-Modified 2 Particles DE VIG 0.4 HCCl 3 EtH 50 nm Absorbance Transmission electron micrograph of TMSmodified particles Wavelength (nm)

10 Formation of Pure PDMS Films using Vinyl-terminated PDMS DE VIG (1) Base: Vinyl-terminated PDMS (2) Curing Agent: Dimethyl, methylhydrogen siloxane R H 3 C H 3 C n n R is usually, sometimes H H 3 C H H 3 C catalyst H 3 C H 2 C C H 2 H 3 C Catalyst is a platinum-based compound H 3 C H 3 C H 3 C H H 3 C H 2 C C H 2 (1) (2)

11 Formation of Pure PDMS Films using Hydroxyl-terminated PDMS DE VIG n H 3 C H H H 3 CH 2 C CH 2 CH 2 catalyst 4 CH 2 H n CH 2 n n (1) (2) H 3 C n (1) Base: Hydroxyl-terminated PDMS (2) Curing Agent: TES Catalyst is stannous octoate

12 Formation of Gold-doped PDMS Films DE VIG PDMS 2 Au-doped PDMS network 0.60 Pure PDMS Film Gold-Doped PDMS Film Absorbance Wavelength (nm)

13 Gold-doped PDMS Films: ptical Properties DE VIG Vinyl-terminated PDMS Hydroxyl-terminated PDMS

14 Gold-doped PDMS Films: ptical Properties DE VIG 1.5 Vinyl-terminated PDMS 0.7 H-terminated PDMS Absorbance Absorbance Wavelength (nm) Wavelength (nm) UV-visible spectra of PDMS films doped with different amounts of The spectrum of the Au particles in chloroform (black) is shown as reference.

15 Gold-doped PDMS Films: ther Properties DE VIG Film in air Film in chloroform

16 Quantum size effects in semiconductor nanoparticles DE VIG size (2-8 nm)

17 Semiconductor-doped PDMS Films: Preliminary Results DE VIG TP-caped nanocrystals with different sizes were synthesized by using organometallic methods. (1) W.W. Yu, X. Peng, Angew. Chem. 2002, 114, 2474; Angew.Chem. Int. Ed. 2002, 41, 2368 (2) J. van Embden, P. Mulvaney, unpublished results. PDMS Catalyst polymerization PDMS network visible light illumination UV light illumination

18 Absorption and Emission of the Semiconductor-doped PDMS Films DE VIG x Intensity, a.u. 3x10 6 2x10 6 1x Absorbance Wavelength (nm)

19 Conclusions Gold-Doped Polydimethylsiloxane Elastomer Films can be easily synthesized by mixing surface modified 2 nanoparticles with the PDMS film precursor. DE VIG The doped PDMS films retain the optical properties of the single nanoparticles. The concentration of the particles can be tailored through the amount or concentration of the nanoparticle colloid added (< 1wt%). Preliminary results show that highly luminescent PDMS films can be obtained by doping the pure films with TP-capped nanoparticles.