Arborescent Amphiphilic Copolymers as Templates for the Preparation of Gold Nanoparticles

Jason DockendorffJason Dockendorff, Mario Gauthier, Mario GauthierDepartment of Chemistry

29th Annual Institute for Polymer Research SymposiumIPR 20

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Outline

1. Focus of Research

2. The Template

3. Results

4. Conclusions & Future WorkIPR 20

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Main Focus

To synthesize a branched polymer template with an inverse micelle morphology for metallic nanoparticle assembly.

Specifically, amphiphilic arborescent copolymers will serve as static scaffolding for metal loading.IP

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Nanoparticle Applications

StabilizedCatalysts

BiologicalLabelling

TEXT TEXT

CellDestruction

Oligonucleotide functionalized nanoparticles exhibit size-dependant light scattering

Functionalized nanoparticles can target then destroy cells when subjected to laser pulses

Applicable to hydrogenation and various coupling reactions

Stable, high turnover, and easy isolation

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Outline

1. Focus and Purpose of Research

2. The Template

3. Results

4. Conclusions & Future WorkIPR 20

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Branched structure obtained from successive grafting reactions

Arborescent Polymers

Linear

- Li, J.; Gauthier, M. Macromolecules 2001, 34, 8918.- Kee, R.A.; Gauthier, M. Macromolecules 1999, 32, 6478.

Functionalization x x x

x xG0

Grafting

*

Copolymers obtained by coupling with a different polymer in the last cycle G1G2

1) Functionalization

2) Grafting

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Synthesis

G0 PS-graft-(P2VP-block-PS)

Θ

Functionalized substrate (G0 PS shown)

Amphiphilic block copolymer (PS-block-P2VP)

amphiphilic arborescent copolymer

PS

P2VP IPR 20

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Polymer loading and reduction

Au0

b

N+

CHH2C

H

b

N

CHH2CbN

CHH2CHAuCl4 -[AuCl4] hydrazine

Other loadable metal salts:– Palladium: Pd(OAC)2

– Platinum: K(PtCl3C2H4)– Rhodium: [Rh(CO)2Cl]2

Selective Reactions

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*Plasma can be used to reduce metal and remove polymer in one step

Plasma

HAuCl4 reduction

Heat

Bare gold nanospheres

Loading and Deposition

Cast on substrate

Polymer stabilized gold nanospheres

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Unique Characteristics

Arborescent Polymer TemplatesArborescent Polymer Templates

Static Structure

SolutionProperties

Activity Tailoring Loading

Versatility

HollowStructure

Size Control

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Agenda

1. Focus and Purpose of Research

2. The Template

3. Results

4. Conclusions & Future WorkIPR 20

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100nm

Preliminary tests

Toluene HAuCl4

PS-b-P2VP

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Arborescent Polymer Loading

PS

P2VP

Gold

G0PS-g-(P2VP-b-PS)IP

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1µm

Polar solvent

Increase the size of PS chains in corona to shield charges

G1PS-g-(P2VP-b-PS)

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PS degree of polymerizationincreased from 65 to 150

G1PS-g-(P2VP-b-PS)

100nm 50nmIP

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100nm

Structure Analysis

Solid Structures: Linear side-chain micelles

Ring Structures: Graft copolymer

Dry

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Structure Analysis

G0

G2

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Purification

“Cloud-point centrifugation”

Addition of a non-solvent to reach cloud point, followed by

centrifugation to isolate graft material.

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Crude Purified

Atomic Force Microscopy

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Chromatography

0

500

1000

1500

2000

2500

12 14 16 18 20 22 24 26

Elution Volume (mL)

DR

I Res

pons

e

PurifiedCrudeBackbone (G1)Side Chains

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Transmission Electron Microscopy

G0 G2IP

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Hydrogen Plasma Etching

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100nm 100nm

Hydrogen Plasma Etching

Reduction and polymer removal(solid state)

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Hydrazine Solution Reduction

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0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

300 350 400 450 500 550 600

Wavelength (nm)

Abs

orba

nce

(arb

itrar

y un

its) Salt

Reduced

UV-Vis Absorbance

(Au+3)

(Au0)

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G1PS-g-(P2VP-b-PS)

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G1PS-g-(P2VP-b-PS)

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PS-g-(P2VP-b-PS)

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Hydrazine Vapour Reduction(Solid State)

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G1PS-g-(P2VP-b-PS)

Reduction by hydrazine vapourIP

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Agenda

1. Focus and Purpose of Research

2. The Template

3. Results

4. Conclusions & Future WorkIPR 20

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Conclusions

• Different arborescent copolymer templates successfully loaded with gold

• Aggregation can be controlled through synthetic procedure and/or solvent changes

• Procedures developed for purification of graft copolymers

• Absorbance fingerprint typical of nanoparticles

• Ring-like structures observed for salt-loaded templates, consistent with hollow metallic nanosphere morphology

• Reduced gold structures rupture in electron beam (evidence for hollowness?)

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Future Work

• Optimization of reduction process to obtain one gold nanoparticle per template molecule.

• Examine and confirm nanoparticle structure and stability.

• Explore use as catalysts after loading with transition metals.IP

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Acknowledgements

Institute for Polymer Research

Lab Colleagues

DWI Institute, RWTH Aachen, Germany

NSERC, OGS, DAAD, Department of ChemistryIPR 20

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Thank you!

Questions?IPR 20

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