Utilizzando Polystyrene-<em> Blocco</em> -poly (Acido acrilico) Rivestiti metallo Nanoparticelle come monomeri per loro omo- e co-polimerizzazione
Summary
We report protocols for “polymerizing” various types of polymer-encapsulated metal nanoparticles into long chains of “homo-“ and “co-polymers”.
Abstract
We present a template-free method for “polymerizing” nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block “copolymers” of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.
Introduction
Despite great advances in the synthesis of nanoparticles over the past two decades, their orderly assembly remains a great challenge. Our synthetic capabilities in putting the basic building blocks together are of critical importance for the exploration and exploitation of their synergistic effects and collective properties. Thus, developing new reaction pathways and exploring the underlying mechanisms are the stepping stones towards the rational synthesis of complex nanodevices.
Among the rich structural variety of possible nanoparticle assemblies, one-dimensional (1D) chains have shown useful applications in nanoelectronics, optoelectronics, and biosensors.1-4 Typically, self-assembly of nanoparticles into chain-like structures requires magnetic or electric dipole interactions, anisotropic electrostatic repulsion, or external templates.5-11 For dipole-induced assembly, one needs nanoparticles with permanent dipoles, such as magnetic nanoparticles and semiconductor nanoparticles under special environments.12-15 For nanoparticles with no permanent dipole, it has been shown that the relatively weaker electrostatic repulsion at the ends of the nanoparticle chains can promote the selective attachment of nanoparticle thereon and thus, 1D chain growth.16,17 Because the nanoparticles can aggregate with each other and with the oligomers, the aggregation often follows the intrinsic step-growth mode, leading to short chain length and the lack of control over branching. Lastly, nanoparticles can be adsorbed onto 1D templates to form chains, but usually it is very difficult to achieve secure anchoring and avoid gaps among the nanoparticles.
With these existing methods, hetero-assembly or “co-polymerization” of nanoparticles is particularly difficult. A few pioneer works have demonstrated the “co-polymerization” of short nanoparticle chains exploiting magnetic dipole18 or electrostatic repulsion.19
Recently, we reported the homo- and co-polymerization of PSPAA-coated nanoparticles into chains.20,21 This new synthetic pathway involves facile colloidal synthesis and generic use of different types of nanoparticles. It affords ultralong chains without branching and allows ready control of their length and width (single-, double-, and triple-line chains). Most importantly, random- and co-polymers of nanoparticles can be synthesized with improved structural control. In this work, we provide video protocols for the related syntheses, intending to give a detailed demonstration and presentation.
Protocol
Representative Results
Discussion
I dettagli meccanicistici le sintesi vengono riportati e discussi nelle precedenti pubblicazioni. 20,21 Qui ci concentriamo sulle motivazioni delle condizioni di sintesi. Per la polimerizzazione delle nanoparticelle, si preferisce che vengono utilizzate nanoparticelle di dimensioni uniformi. Seguiamo procedure di letteratura per ottenere le nanoparticelle uniformi Au, 23 Au nanorods, 24 e nanofili Te. 25 In generale, una migliore uniformità formato può essere ottenuta quando…
Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors thank the NRF (CRP-4-2008-06), A*Star (SERC 112-120-2011) and MOE (RG14/13) Singapore for financial supports.
Materials
| Gold(III) chloride trihydrate, ACS reagent, ≥49.0% Au basis |
Sigma-Aldrich | G4022 | HAuCl4 |
| Sodium citrate dihydrate, 99% | Alfa Aesar | A12274 | |
| Sodium borohydride, ≥99% |
Sigma-Aldrich | 71321, Fluka | |
| Hexadecyltrimethylammonium bromide,≥98% | Sigma-Aldrich | H5882 | CTAB |
| Silver Nitrate, 99.9999% trace metals basis | Sigma-Aldrich | 204390 | |
| L-ascorbic acid,BioXtra, ≥99.0%, crystalline |
Sigma-Aldrich | A5960 | |
| Tellurium dioxide,≥99% | Sigma-Aldrich | 243450 | |
| Hydrazine monohydrate, 64-65 %, reagent grade, 98% | Sigma-Aldrich | 207942 | |
| Poly(styrene-b-acrylic acid)(PS154-PAA49) | Polymer Source | P4673A-SAA | PS16000-PAA3500 |
| Poly(styrene-b-acrylic acid)(PS144-PAA28) | Polymer Source | P4002-SAA | PS15000-PAA1600 |
| 2-Naphthalenethiol, ≥99.0% (GC) |
Sigma-Aldrich | 88910, Fluka | |
| Sodium dodecyl sulfate, 99% | Alfa Aesar | A11183 | |
| single wall carbon nanotubes, 99% ultra-pure | NanoIntegris | PC10344a | |
| Sodium hydroxide | Sinopharm | S1900136 | |
| 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (sodium salt) | Avanti polar lipids | 870160P | PSH |
| N,N-dimethylformamide | Merck | SA4s640012 | |
| Ethanol, absolute | Fischer | E/0650DF/17 | |
| Hydrochloric acid, 37% | Honey well | 10189005 | Dilute to 1M before use |
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