Controlling Nanoparticle Location via Confined Assembly in Electrospun Block Copolymer Nanofibers

Kalra, Vibha; Lee, Jun Young; Lee, Jung Hun; Lee, Seung Koo; Márquez, Manuel; Wiesner, Ulrich; Joo, Yong Lak

doi:10.1002/smll.200800279

Cited by 74 publications

(72 citation statements)

References 30 publications

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“…The mechanical, optical, and electrical properties of a nanocomposite rely not only on the compositions of its constituent phases but also on its nanostructures and, therefore, achieving high performance nanocomposites often requires precise control of the spatial distribution of the nanoparticles in the polymeric host [2,[5][6][7][8][9][10]. To prevent macrophase separation, particles are usually grafted by a brush of short polymers which are chemically identical to one component of the block copolymer.…”

Section: Introductionmentioning

confidence: 99%

Controllable nanostructural transitions in grafted nanoparticle-block copolymer composites

Feng

2010

Nano Res.

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We report a theoretical investigation of self-assembled nanostructures of polymer-grafted nanoparticles in a block copolymer and explore underlying physical mechanisms by employing the self-consistent field method. By varying the particle concentration or the chain length and density of the grafted polymer, one can not only create various ordered morphologies (e.g., lamellar or hexagonally packed patterns) but also control the positions of nanoparticles either at the copolymer interfaces or in the center of one-block domains. The nanostructural transitions we here report are mainly attributed to the competition between entropy and enthalpy.

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Section: Introductionmentioning

confidence: 99%

Controllable nanostructural transitions in grafted nanoparticle-block copolymer composites

Feng

2010

Nano Res.

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“…[24][25][26][27] For example, preferential incorporation of nanoscale particles into one of the oriented * To whom correspondence should be addressed. Telephone: +90 232 750 75 11.…”

Section: Introductionmentioning

confidence: 99%

Controlling Spontaneous Emission of CdSe Nanoparticles Dispersed in Electrospun Fibers of Polycarbonate Urethane

et al. 2009

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Luminescent fibrous composite films consisting of submicrometer diameter fibers were prepared by electrospinning of segmented polycarbonate urethane (PCU) in dimethyl formamide and tri-n-octylphosphine oxide (TOPO)-capped CdSe nanocrystals (5 nm in diameter) in toluene. Using a pair of conductive electrodes separated with an air gap, we successfully produced randomly deposited and uniaxially aligned electrospun fibers. The surface structure of the electrospun fibers was studied using atomic force microscopy (AFM) and was compared to the corresponding film prepared by casting. In cast film, tapping mode AFM imaging suggests that hard urethane segments organize into rodlike morphology dispersed in soft polycarbonate. When PCU/CdSe dispersions were subjected to electrospinning, copolymer domains were forced to arrange into lamella along the fiber axis due to elongational flow and high stretching. Molecular orientation in the domains of the composite fibers was confirmed by polarized infrared spectroscopy. We demonstrated that formation of the oriented domains by electrospinning develops a hierarchical structure, which consequently modifies spectral properties because new multiple sharp lines appeared in the photoluminescence (PL) spectra of the fibers. In contrast to randomly deposited fibers, the PL intensity of uniaxially aligned fibers was found to be angle dependent. We propose that the elongated internal structure within the fibers controls the spontaneous emission of CdSe nanoparticles dispersed throughout the electrospun mat. A discussion on the nature of the controlled spontaneous emission is provided.

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“…33 They also successfully demonstrated the added functionality of these self-assembled materials with magnetic NPs and also showed evolution of BCP morphology by swelling of the PI domain with addition of the selective NPs. 33 These continuous materials, with high surface area-to-mass ratio and good production rate, showed good promises in applications such as magnetic storage media and catalysts.…”

Section: ■ Introductionmentioning

confidence: 95%

Role of Nanoparticle Selectivity in the Symmetry Breaking of Cylindrically Confined Block Copolymers

et al. 2014

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We have comprehensively studied the effect of nanoparticle selectivity on the self-assembly of symmetrical block copolymer (BCP) under cylindrical confinement using simulation and experiment. For the simulation, a coarse-grained molecular dynamics (CGMD) simulation has been utilized, and we investigated the confined assembly using nanoparticles with three different interactions with block copolymer: (i) neutral to both A (wall-attractive) and B (wall-repulsive) phases, (ii) B domain selective, and (iii) A domain selective. It is predicted that nonselective (neutral) nanoparticles (NPs) tend to be placed near the interface between radially alternating layers of A or B domains, while selective (A or B) NPs swell the corresponding phase, inducing discrete asymmetrical morphologies. We also find that pure asymmetrical BCP forms more radially perforated morphologies, while symmetrical BCP/NP forms more discrete morphologies. Experimentally, we have incorporated gold or magnetite NPs with the matching three types of selectivity toward symmetrical diblock PS-b-PI and electrospun them. The morphologies observed from our study have been quantified by morphological classification numbers to identify the degree of asymmetry formed. The qualitative and quantitative comparisons between experiment and simulation confirm the validity of the simulation tool and shed light on the NP's role on breaking the symmetry of BCP under cylindrical confinement. ■ INTRODUCTIONNanoparticles (NPs) have attracted much research interest for a wide variety of potential applications in biomedical, optical, and electronic fields. 1−4 In particular, nanoparticles are successfully incorporated into a polymer matrix to enhance material properties. 5−7 Due to their high surface energy, however, nanoparticles often self-aggregate in the polymer matrix, which prevents utilization of their large interfacial volume. Synergetic effects can arise from periodic spatial placement of the nanoparticles to fully maximize its utility. As one solution, the block copolymer has been used as a template for ordered placement of nanoparticles. Block copolymer (BCP) solutions and melts are known to self-assemble into a variety of nanoscale morphologies including spheres, rods, micelles, lamellae, vesicle tubules, and cylinders 8,9 depending on the volume fraction and interaction parameter between different blocks. Self-assembly of BCP has attracted increasing interest in recent years for applications in nanotechnology. 10,11 Precise control over the size, shape, and periodicity of these nanoscale microdomains is the key factor in providing opportunities for realization of nanoscale systems. It has been reported that BCP exhibits novel morphologies not seen in the bulk under a confined domain (D) which is commensurate with its equilibrium bulk periodic spacing (L 0 ). Shin et al. confined symmetrical polystyrene-b-polybutadiene (PS-b-PBD) in an alumina nanopore to obtain concentric ring morphology which was not observed in the bulk. 12 There are also other types of confi...

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Controlling Nanoparticle Location via Confined Assembly in Electrospun Block Copolymer Nanofibers

Cited by 74 publications

References 30 publications

Controllable nanostructural transitions in grafted nanoparticle-block copolymer composites

Controllable nanostructural transitions in grafted nanoparticle-block copolymer composites

Controlling Spontaneous Emission of CdSe Nanoparticles Dispersed in Electrospun Fibers of Polycarbonate Urethane

Role of Nanoparticle Selectivity in the Symmetry Breaking of Cylindrically Confined Block Copolymers

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