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. 2019 Feb 28;9(3):318.
doi: 10.3390/nano9030318.

Rapid Self-Assembly of Metal/Polymer Nanocomposite Particles as Nanoreactors and Their Kinetic Characterization

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Free PMC article

Rapid Self-Assembly of Metal/Polymer Nanocomposite Particles as Nanoreactors and Their Kinetic Characterization

Andrew Harrison et al. Nanomaterials (Basel). .
Free PMC article

Abstract

Self-assembled metal nanoparticle-polymer nanocomposite particles as nanoreactors are a promising approach for performing liquid phase reactions using water as a bulk solvent. In this work, we demonstrate rapid, scalable self-assembly of metal nanoparticle catalyst-polymer nanocomposite particles via Flash NanoPrecipitation. The catalyst loading and size of the nanocomposite particles can be tuned independently. Using nanocomposite particles as nanoreactors and the reduction of 4-nitrophenol as a model reaction, we study the fundamental interplay of reaction and diffusion. The induction time is affected by the sequence of reagent addition, time between additions, and reagent concentration. Combined, our experiments indicate the induction time is most influenced by diffusion of sodium borohydride. Following the induction time, scaling analysis and effective diffusivity measured using NMR indicate that the observed reaction rate are reaction- rather than diffusion-limited. Furthermore, the intrinsic kinetics are comparable to ligand-free gold nanoparticles. This result indicates that the polymer microenvironment does not de-activate or block the catalyst active sites.

Keywords: Flash Nanoprecipitation; catalyst confinement; diffusion; nanoreactor.

Conflict of interest statement

The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

Figures

Figure 1
Figure 1
Polymer nanoreactors were fabricated via self-directed assembly. (a) DLS confirms the uniform size distribution of the ~130 nm self-assembled polymer nanoreactors (black circles) and confirms that the size is the same after the reduction of 4-nitrophenol (red squares). (b) UV-vis analysis shows that the absorbance of the gold nanoparticle remains unchanged through the solvent switch from toluene (black filled circles) to tetrahydrofuran (THF) (red open circles). A red-shift is seen upon encapsulation within polymer nanoreactors (blue open diamonds) due to close proximity of the encapsulated gold nanoparticles. (c) TEM imaging demonstrates that multiple gold nanoparticles were encapsulated within the core of the nanoreactors.
Figure 2
Figure 2
Hydrodynamic diameter of polystyrene nanoreactors measured by DLS with varying total nanoreactor material concentration in the formulation. (a) By varying the total material concentration with constant ratio of components tunable nanoreactor size between 100–200 nm. (b) By varying the gold to polystyrene co-precipitate ratio at a constant nanoreactor core volume (red squares), as opposed to constant mass ratio (black circles), the nominal gold loading of polystyrene nanoreactors can be tuned at constant nanoreactor size (~130 nm). The standard formulation (4 wt % nominal gold loading, 2.4 mg/mL) is shown by the red triangle.
Figure 3
Figure 3
The effect of the sequence of reagent addition on the induction time of the 4-nitrophenol reaction. In all experiments, the 4-nitrophenol and sodium borohydride concentration followed standard conditions of 0.01 mM and 0.01 M, respectively. The indicated reagent was the first to be added, after which the reagent was allowed to equilibrate in the solution for either 1 min (black striped bars) or 10 min (red solid bars). The end of the equilibration period was the addition of the second reagent, at which point the reaction could progress.
Figure 4
Figure 4
The effect of sodium borohydride equilibration on the induction time of the 4-nitrophenol reaction. Standard reagent concentrations of 0.01 mM and 0.01 M were used for 4-nitrophenol and sodium borohydride, respectively. Data points marked with an asterisk (*) are significantly different than each other (p < 0.1).

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References

    1. Zhang X., Cardozo A.F., Chen S., Zhang W., Julcour C., Lansalot M., Blanco J.F., Gayet F., Delmas H., Charleux B., et al. Core-Shell Nanoreactors for Efficient Aqueous Biphasic Catalysis. Chem. A Eur. J. 2014;20:15505–15517. doi: 10.1002/chem.201403819. - DOI - PubMed
    1. Cotanda P., Petzetakis N., O’reilly R.K. Catalytic Polymeric Nanoreactors: More than a Solid Supported Catalyst. MRS Commun. 2012;2:119–126. doi: 10.1557/mrc.2012.26. - DOI
    1. Walther A., Muller A.H.E. Janus Particles: Synthesis, Self-Assembly, Physical Properties, and Applications. Chem. Rev. 2013;113:5194–5261. doi: 10.1021/cr300089t. - DOI - PubMed
    1. Lipshutz B.H., Ghorai S. “Designer”-Surfactant-Enabled Cross-Couplings in Water at Room Temperature. Aldrichim. Acta. 2012;45:3–16. doi: 10.1016/j.immuni.2010.12.017.Two-stage. - DOI - PMC - PubMed
    1. Lipshutz B.H., Ghorai S. Transitioning Organic Synthesis from Organic Solvents to Water. What’s Your E-Factor? Green Chem. 2014;16:3660–3679. doi: 10.1039/C4GC00503A. - DOI - PMC - PubMed
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