Arborescent Polymers as Templates for the Preparation of Metallic Nanoparticles Jason Dockendorff Department of Chemistry University of Waterloo
Outline 1. 1. Focus and Purpose of of Research 2. 2. The Template 3. 3. Results 4. 4. Conclusions & Future Work
Main Focus To synthesize and use amphiphilic arborescent copolymers as templates for the construction of metallic nanoparticles.
Nanoparticle Applications Metal-loaded Polymers Modified Metallic Nanoparticles Stabilized Catalysts Biological Labelling Destructive Cell Targeting
Nanoparticle Applications Biological labelling Jin, R.; Wu, G.; Li, Z.; Mirkin, C.; Schatz, G. J. Am. Chem. Soc. 2003, 125, 1643.
Nanoparticle Applications Destructive cell targeting Pitsillides, C.; Edwin, J.; Xunbin, W.; Anderson, R.; Lin, C. Biophys. J. 2003, 84, 4023. Polymer stabilized colloid catalysts Schimpf, S. Lucas, M.; Mohr, C.; Rodemerck, U.; Brückner, A.; Radnik, J.; Hofmeister, H.; Claus, P. Catalysis Today 2002, 72, 63.
Outline 1. 1. Focus Focus and and Purpose Purpose of of Research Research 2. 2. The Template 3. 3. Results Results 4. 4. Conclusions Conclusions & Future Future Work Work
Arborescent Polymers Branched structure obtained from successive grafting reactions Linear 1) Functionalization 2) Grafting * G0 G1 G2 Copolymers obtained by coupling with a different polymer in the last cycle - Li, J.; Gauthier, M. Macromolecules 2001, 34, 8918. - Kee, R.A.; Gauthier, M. Macromolecules 1999, 32, 6478.
Synthesis Θ Functionalized substrate (G0 PS shown) Amphiphilic block copolymer (P2VP-block-PS) amphiphilic arborescent copolymer G0 PS-graft-(P2VPblock-PS)
Selective Reactions Polymer loading and reduction H 2 C CH b N H 2 C CH b HAuCl 4 - [AuCl 4 ] hydrazine N + H H 2 C CH b N Au 0 Other loadable metal salts: Palladium - Pd(OAC) 2 Platinum - K(PtCl 3 C 2 H 4 ) Rhodium - [Rh(CO) 2 Cl] 2
Loading and Deposition HAuCl 4, Pd(OAC) 2, K(PtCl 3 C 2 H 4 ), or [Rh(CO) 2 Cl] 2 reduction *Plasma can be used to reduce metal and remove polymer in one step Plasma Cast on substrate Heat Bare metallic nanospheres Polymer stabilized metallic nanospheres
Arborescent Polymer Templates Unique Characteristics Static Structure Size Control Activity Tailoring Hollow Structure Loading Versatility
Agenda 1. 1. Focus Focus and and Purpose Purpose of of Research Research 2. 2. The The Template Template 3. 3. Results 4. 4. Conclusions Conclusions & Future Future Work Work
Preliminary tests Linear block copolymer used to validate loading procedure PS-b-P2VP M w (PS) = 29 000 (DP=277) M w (P2VP)= 33 500 (DP=320) PS(277)-b-P2VP(320) DP Degree of Polymerization
PS(277)-b-P[2VP(HAuCl 4 ) 0.5 (320)] 0.5 eq loading 100nm
Arborescent Polymer Loading
G1PS-g-{PS(66)-b-P[2VP(HAuCl 4 ) 0.5 (89)]} 1µm Extensive aggregation Increase length of PS chains in corona to shield charges
G1PS-g-{PS(144)-b-P[2VP(HAuCl 4 ) 0.5 (144)]} 100nm
G1PS-g-{PS(144)-b-P[2VP(HAuCl 4 ) 0.5 (144)]} 50nm
Size Populations 8 7 G1PS-g -{PS(144) -b -P[2VP(HAuCl 4 ) 0.5 (144) ]} Size Populations Population I (solid): 20 ± 2 nm Population II (rings): 32 ± 2 nm 6 5 Count 4 3 2 1 0 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Diameter (nm)
Structure Analysis Solid Structures: Linear side-chain micelles Dry Ring Structures: Graft copolymer 100nm
Structure Analysis Electron Beam Arborescent Molecule TEM Grid
Structure Analysis Could the rings be aggregates of side-chain micelles? 50nm Toluene THF
Purification 2µm 2µm
Size and Aggregation Can aggregation be controlled using a more polar solvent? 1µm Toluene THF
Size and Aggregation Toluene THF Sample Core (G1PS) 24.4 1st ± 0.3 2nd 23.8 ± 0.6 26.9 1st ± 0.1 2nd 26.3 ± 0.2 PS(66 )-b -P2VP(89 ) 50.0 ± 0.4 49.5 ± 0.4 56.1 ± 0.2 55.3 ± 0.4 + 0.5eq Au 85 ± 7 61 ± 4 51.7 ± 0.6 50.8 ± 0.4 Core (G1PS) 28.2 ± 0.1 26.6 ± 0.2 29.6 ± 0.3 28.2 ± 0.2 PS(95 )-b -P2VP(95 ) 53.2 ± 0.2 52 ± 1 63.2 ± 0.2 61.5 ± 0.2 + 0.5eq Au 90 ± 1 77 ± 2 56.2 ± 0.4 54.5 ± 0.5 PS(144 )-b -P2VP(144 ) 72.9 ± 0.9 67 ± 1 76.3 ± 0.5 74.2 ± 0.9 + 0.5eq Au 122 ± 3 97 ± 3 64.1 ± 0.2 63.1 ± 0.4
Plasma Etching and Reduction
Hydrogen Plasma Etching 100nm 100nm
Hydrazine Reduction 250nm
UV-Vis Absorbance Absorbance (a.u., normalized to peak) 1.2 1 0.8 0.6 0.4 0.2 HAuCl4 JD004 JD013 JD014 Reduced 0 300 350 400 450 500 550 600 Wavelength (nm)
Agenda 1. 1. Focus Focus and and Purpose Purpose of of Research Research 2. 2. The The Template Template 3. 3. Results Results 4. 4. Conclusions & Future Work
Conclusions Different arborescent copolymer templates successfully loaded with gold Ring-like structures observed, consistent with hollow metallic nanosphere morphology Aggregation can be controlled through synthetic procedure and/or solvent changes
Future Work Optimization and control of metal reduction and polymer etching to yield one metallic particle per micelle. Load templates with catalytic materials and test for stability, selectivity, and reactivity Synthesize a series of arborescent copolymers with systematic variations in dimensions of core and shell
Acknowledgements Dr. Mario Gauthier & Lab Colleagues Dr. Jean Duhamel & Lab Colleagues DWI Institute, RWTH Aachen, Germany Dr. Martin Möller Dr. Ahmed Mourran Dr. Oliver Weichold Yvonne Noppeney NSERC, OGS, DAAD, Department of Chemistry
Thank you! Questions?