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A general route to nanocrystal kebabs periodically assembled on stretched flexible polymer shish.

Xu H, Xu Y, Pang X, He Y, Jung J, Xia H, Lin Z - Sci Adv (2015)

Bottom Line: However, this is an area where progress has been slower.These nanostructures can be regarded as organic-inorganic shish-kebabs, in which nanodisc kebabs are periodically situated on a stretched polymer shish.Simulations based on self-consistent field theory reveal that the formation of organic-inorganic shish-kebabs is guided by the self-assembled elongated star-like diblock copolymer constituents constrained on the highly stretched polymer chain.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. ; State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.

ABSTRACT
Assembling nanoparticles into one-dimensional (1D) nanostructures with precisely controlled size and shape renders the exploration of new properties and construction of 1D miniaturized devices possible. The physical properties of such nanostructures depend heavily on the size, chemical composition, and surface chemistry of nanoparticle constituents, as well as the close proximity of adjacent nanoparticles within the 1D nanostructure. Chemical synthesis provides an intriguing alternative means of creating 1D nanostructures composed of self-assembled nanoparticles in terms of material diversity, size controllability, shape regularity, and low-cost production. However, this is an area where progress has been slower. We report an unconventional yet general strategy to craft an exciting variety of 1D nanonecklace-like nanostructures comprising uniform functional nanodiscs periodically assembled along a stretched flexible polymer chain by capitalizing on judiciously designed amphiphilic worm-like diblock copolymers as nanoreactors. These nanostructures can be regarded as organic-inorganic shish-kebabs, in which nanodisc kebabs are periodically situated on a stretched polymer shish. Simulations based on self-consistent field theory reveal that the formation of organic-inorganic shish-kebabs is guided by the self-assembled elongated star-like diblock copolymer constituents constrained on the highly stretched polymer chain.

No MeSH data available.


TEM images of (A) semiconductor CdSe, (B) magnetic Fe3O4, and (C) ferroelectric BaTiO3 nanonecklaces.(D) Schematic illustration of an individual nanonecklace showing dimensions: the diameter (D) and thickness (t) of a nanodisc, the spacing (s) between adjacent nanodiscs, and the total length (L) of a nanonecklace. The PS chains that intimately and permanently capped on the necklace surface, and the PEO stem that connected all nanodiscs are omitted for clarity in (D).
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Figure 2: TEM images of (A) semiconductor CdSe, (B) magnetic Fe3O4, and (C) ferroelectric BaTiO3 nanonecklaces.(D) Schematic illustration of an individual nanonecklace showing dimensions: the diameter (D) and thickness (t) of a nanodisc, the spacing (s) between adjacent nanodiscs, and the total length (L) of a nanonecklace. The PS chains that intimately and permanently capped on the necklace surface, and the PEO stem that connected all nanodiscs are omitted for clarity in (D).

Mentions: We first synthesized CdSe nanonecklace using amphiphilic worm-like PAA-b-PS diblock copolymer as template to demonstrate the effectiveness of our strategy in producing high-quality nanonecklace-like structures (Fig. 2A). The growth mechanism involves loading of the inner PAA region of amphiphilic worm-like PAA-b-PS with the desired metal moieties. A certain amount of amphiphilic worm-like PAA-b-PS diblock copolymers (sample 1 in Table 1) was dissolved in a mixture of N,N-dimethylformamide (DMF) and benzyl alcohol (BA) at DMF/BA = 9:1 (volume ratio) at room temperature, followed by the addition of CdSe precursors [that is, Cd(acac)2 and Se]. Tri-n-octylphosphine (TOP) to act as the reducing agent for Se. The inner PAA blocks in worm-like PAA-b-PS diblock copolymers are highly hydrophilic, rendering the preferential incorporation of precursors into the interior space occupied by PAA blocks through strong coordination interaction between the metal moieties of precursors and the carboxyl groups of PAA (30). Consequently, CdSe nanodiscs with PS chains capped on the surface were formed into a well-proportioned nanonecklace-like structure as unambiguously evidenced by TEM imaging obtained from a dilute CdSe solution. The emergence of highly oriented, long CdSe necklace suggested a template-assisted growth of CdSe nanodiscs. The CdSe nanodiscs capped by PS chains were connected by the PEG chain and closely packed along it. In this context, such nanostructures are reminiscent of nanoscopic organic-inorganic shish-kebabs (31, 32), in which nanodisc kebabs were closely and periodically spaced on the stretched PEG shish. It is noteworthy that the PEG shish was not visible under TEM because it is a single chain and has low electron density compared to inorganic CdSe nanodiscs. Similarly, the PS chains tethered on the surface of the nanodisc and PAA within the nanodisc were also not observed.


A general route to nanocrystal kebabs periodically assembled on stretched flexible polymer shish.

Xu H, Xu Y, Pang X, He Y, Jung J, Xia H, Lin Z - Sci Adv (2015)

TEM images of (A) semiconductor CdSe, (B) magnetic Fe3O4, and (C) ferroelectric BaTiO3 nanonecklaces.(D) Schematic illustration of an individual nanonecklace showing dimensions: the diameter (D) and thickness (t) of a nanodisc, the spacing (s) between adjacent nanodiscs, and the total length (L) of a nanonecklace. The PS chains that intimately and permanently capped on the necklace surface, and the PEO stem that connected all nanodiscs are omitted for clarity in (D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643824&req=5

Figure 2: TEM images of (A) semiconductor CdSe, (B) magnetic Fe3O4, and (C) ferroelectric BaTiO3 nanonecklaces.(D) Schematic illustration of an individual nanonecklace showing dimensions: the diameter (D) and thickness (t) of a nanodisc, the spacing (s) between adjacent nanodiscs, and the total length (L) of a nanonecklace. The PS chains that intimately and permanently capped on the necklace surface, and the PEO stem that connected all nanodiscs are omitted for clarity in (D).
Mentions: We first synthesized CdSe nanonecklace using amphiphilic worm-like PAA-b-PS diblock copolymer as template to demonstrate the effectiveness of our strategy in producing high-quality nanonecklace-like structures (Fig. 2A). The growth mechanism involves loading of the inner PAA region of amphiphilic worm-like PAA-b-PS with the desired metal moieties. A certain amount of amphiphilic worm-like PAA-b-PS diblock copolymers (sample 1 in Table 1) was dissolved in a mixture of N,N-dimethylformamide (DMF) and benzyl alcohol (BA) at DMF/BA = 9:1 (volume ratio) at room temperature, followed by the addition of CdSe precursors [that is, Cd(acac)2 and Se]. Tri-n-octylphosphine (TOP) to act as the reducing agent for Se. The inner PAA blocks in worm-like PAA-b-PS diblock copolymers are highly hydrophilic, rendering the preferential incorporation of precursors into the interior space occupied by PAA blocks through strong coordination interaction between the metal moieties of precursors and the carboxyl groups of PAA (30). Consequently, CdSe nanodiscs with PS chains capped on the surface were formed into a well-proportioned nanonecklace-like structure as unambiguously evidenced by TEM imaging obtained from a dilute CdSe solution. The emergence of highly oriented, long CdSe necklace suggested a template-assisted growth of CdSe nanodiscs. The CdSe nanodiscs capped by PS chains were connected by the PEG chain and closely packed along it. In this context, such nanostructures are reminiscent of nanoscopic organic-inorganic shish-kebabs (31, 32), in which nanodisc kebabs were closely and periodically spaced on the stretched PEG shish. It is noteworthy that the PEG shish was not visible under TEM because it is a single chain and has low electron density compared to inorganic CdSe nanodiscs. Similarly, the PS chains tethered on the surface of the nanodisc and PAA within the nanodisc were also not observed.

Bottom Line: However, this is an area where progress has been slower.These nanostructures can be regarded as organic-inorganic shish-kebabs, in which nanodisc kebabs are periodically situated on a stretched polymer shish.Simulations based on self-consistent field theory reveal that the formation of organic-inorganic shish-kebabs is guided by the self-assembled elongated star-like diblock copolymer constituents constrained on the highly stretched polymer chain.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. ; State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.

ABSTRACT
Assembling nanoparticles into one-dimensional (1D) nanostructures with precisely controlled size and shape renders the exploration of new properties and construction of 1D miniaturized devices possible. The physical properties of such nanostructures depend heavily on the size, chemical composition, and surface chemistry of nanoparticle constituents, as well as the close proximity of adjacent nanoparticles within the 1D nanostructure. Chemical synthesis provides an intriguing alternative means of creating 1D nanostructures composed of self-assembled nanoparticles in terms of material diversity, size controllability, shape regularity, and low-cost production. However, this is an area where progress has been slower. We report an unconventional yet general strategy to craft an exciting variety of 1D nanonecklace-like nanostructures comprising uniform functional nanodiscs periodically assembled along a stretched flexible polymer chain by capitalizing on judiciously designed amphiphilic worm-like diblock copolymers as nanoreactors. These nanostructures can be regarded as organic-inorganic shish-kebabs, in which nanodisc kebabs are periodically situated on a stretched polymer shish. Simulations based on self-consistent field theory reveal that the formation of organic-inorganic shish-kebabs is guided by the self-assembled elongated star-like diblock copolymer constituents constrained on the highly stretched polymer chain.

No MeSH data available.