Nanomaterials

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18 pages, 1747 KiB

Open AccessArticle

Direct Measurement of Sedimentation Coefficient Distributions in Multimodal Nanoparticle Mixtures

by Claudia Simone Plüisch, Rouven Stuckert and Alexander Wittemann

Nanomaterials 2021, 11(4), 1027; https://doi.org/10.3390/nano11041027 - 17 Apr 2021

Cited by 10 | Viewed by 3649

Abstract

Differential centrifugal sedimentation (DCS) is based on physical separation of nanoparticles in a centrifugal field prior to their analysis. It is suitable for resolving particle populations, which only slightly differ in size or density. Agglomeration presents a common problem in many natural and [...] Read more.

Differential centrifugal sedimentation (DCS) is based on physical separation of nanoparticles in a centrifugal field prior to their analysis. It is suitable for resolving particle populations, which only slightly differ in size or density. Agglomeration presents a common problem in many natural and engineered processes. Reliable data on the agglomeration state are also crucial for hazard and risk assessment of nanomaterials and for grouping and read-across of nanoforms. Agglomeration results in polydisperse mixtures of nanoparticle clusters with multimodal distributions in size, density, and shape. These key parameters affect the sedimentation coefficient, which is the actual physical quantity measured in DCS, although the method is better known for particle sizing. The conversion into a particle size distribution is, however, based on the assumption of spherical shapes. The latter disregards the influence of the actual shape on the sedimentation rate. Sizes obtained in this way refer to equivalent diameters of spheres that sediment at the same velocity. This problem can be circumvented by focusing on the sedimentation coefficient distribution of complex nanoparticle mixtures. Knowledge of the latter is essential to implement and optimize preparative centrifugal routines, enabling precise and efficient sorting of complex nanoparticle mixtures. The determination of sedimentation coefficient distributions by DCS is demonstrated based on supracolloidal assemblies, which are often referred to as “colloidal molecules”. The DCS results are compared with sedimentation coefficients obtained from hydrodynamic bead-shell modeling. Furthermore, the practical implementation of the analytical findings into preparative centrifugal separations is explored. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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12 pages, 7938 KiB

Open AccessEditor’s ChoiceArticle

Resist-Free Directed Self-Assembly Chemo-Epitaxy Approach for Line/Space Patterning

by Tommaso Jacopo Giammaria, Ahmed Gharbi, Anne Paquet, Paul Nealey and Raluca Tiron

Nanomaterials 2020, 10(12), 2443; https://doi.org/10.3390/nano10122443 - 7 Dec 2020

Cited by 3 | Viewed by 2786

Abstract

This work reports a novel, simple, and resist-free chemo-epitaxy process permitting the directed self-assembly (DSA) of lamella polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymers (BCPs) on a 300 mm wafer. 193i lithography is used to manufacture topographical guiding silicon oxide line/space patterns. The critical [...] Read more.

This work reports a novel, simple, and resist-free chemo-epitaxy process permitting the directed self-assembly (DSA) of lamella polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymers (BCPs) on a 300 mm wafer. 193i lithography is used to manufacture topographical guiding silicon oxide line/space patterns. The critical dimension (CD) of the silicon oxide line obtained can be easily trimmed by means of wet or dry etching: it allows a good control of the CD that permits finely tuning the guideline and the background dimensions. The chemical pattern that permits the DSA of the BCP is formed by a polystyrene (PS) guide and brush layers obtained with the grafting of the neutral layer polystyrene-random-polymethylmethacrylate (PS-r-PMMA). Moreover, data regarding the line edge roughness (LER) and line width roughness (LWR) are discussed with reference to the literature and to the stringent requirements of semiconductor technology. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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11 pages, 13153 KiB

Open AccessArticle

Directed Self-Assembly of Polystyrene Nanospheres by Direct Laser-Writing Lithography

by Eleonora Cara, Federico Ferrarese Lupi, Matteo Fretto, Natascia De Leo, Mauro Tortello, Renato Gonnelli, Katia Sparnacci and Luca Boarino

Nanomaterials 2020, 10(2), 280; https://doi.org/10.3390/nano10020280 - 7 Feb 2020

Cited by 9 | Viewed by 3271

Abstract

In this work, we performed a systematic study on the effect of the geometry of pre-patterned templates and spin-coating conditions on the self-assembling process of colloidal nanospheres. To achieve this goal, large-scale templates, with different size and shape, were generated by direct laser-writer [...] Read more.

In this work, we performed a systematic study on the effect of the geometry of pre-patterned templates and spin-coating conditions on the self-assembling process of colloidal nanospheres. To achieve this goal, large-scale templates, with different size and shape, were generated by direct laser-writer lithography over square millimetre areas. When deposited over patterned templates, the ordering dynamics of the self-assembled nanospheres exhibits an inverse trend with respect to that observed for the maximisation of the correlation length

ξ

on a flat surface. Furthermore, the self-assembly process was found to be strongly dependent on the height (H) of the template sidewalls. In particular, we observed that, when H is 0.6 times the nanospheres diameter and spinning speed 2500 rpm, the formation of a confined and well ordered monolayer is promoted. To unveil the defects generation inside the templates, a systematic assessment of the directed self-assembly quality was performed by a novel method based on Delaunay triangulation. As a result of this study, we found that, in the best deposition conditions, the self-assembly process leads to well-ordered monolayer that extended for tens of micrometres within the linear templates, where 96.2% of them is aligned with the template sidewalls. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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19 pages, 4444 KiB

Open AccessArticle

Characterisation of the PS-PMMA Interfaces in Microphase Separated Block Copolymer Thin Films by Analytical (S)TEM

by Julius Bürger, Vinay S. Kunnathully, Daniel Kool, Jörg K. N. Lindner and Katharina Brassat

Nanomaterials 2020, 10(1), 141; https://doi.org/10.3390/nano10010141 - 13 Jan 2020

Cited by 8 | Viewed by 5229

Abstract

Block copolymer (BCP) self-assembly is a promising tool for next generation lithography as microphase separated polymer domains in thin films can act as templates for surface nanopatterning with sub-20 nm features. The replicated patterns can, however, only be as precise as their templates. [...] Read more.

Block copolymer (BCP) self-assembly is a promising tool for next generation lithography as microphase separated polymer domains in thin films can act as templates for surface nanopatterning with sub-20 nm features. The replicated patterns can, however, only be as precise as their templates. Thus, the investigation of the morphology of polymer domains is of great importance. Commonly used analytical techniques (neutron scattering, scanning force microscopy) either lack spatial information or nanoscale resolution. Using advanced analytical (scanning) transmission electron microscopy ((S)TEM), we provide real space information on polymer domain morphology and interfaces between polystyrene (PS) and polymethylmethacrylate (PMMA) in cylinder- and lamellae-forming BCPs at highest resolution. This allows us to correlate the internal structure of polymer domains with line edge roughnesses, interface widths and domain sizes. STEM is employed for high-resolution imaging, electron energy loss spectroscopy and energy filtered TEM (EFTEM) spectroscopic imaging for material identification and EFTEM thickness mapping for visualisation of material densities at defects. The volume fraction of non-phase separated polymer species can be analysed by EFTEM. These methods give new insights into the morphology of polymer domains the exact knowledge of which will allow to improve pattern quality for nanolithography. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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10 pages, 8066 KiB

Open AccessArticle

Enhancing Photoluminescence Quenching in Donor–Acceptor PCE11:PPCBMB Films through the Optimization of Film Microstructure

by Otto Todor-Boer, Ioan Petrovai, Raluca Tarcan, Adriana Vulpoi, Leontin David, Simion Astilean and Ioan Botiz

Nanomaterials 2019, 9(12), 1757; https://doi.org/10.3390/nano9121757 - 10 Dec 2019

Cited by 11 | Viewed by 3198

Abstract

We show that a precise control of deposition speed during the fabrication of polyfullerenes and donor polymer films by convective self-assembly leads to an optimized film microstructure comprised of interconnected crystalline polymer domains comparable to molecular dimensions intercalated with similar polyfullerene domains. Moreover, [...] Read more.

We show that a precise control of deposition speed during the fabrication of polyfullerenes and donor polymer films by convective self-assembly leads to an optimized film microstructure comprised of interconnected crystalline polymer domains comparable to molecular dimensions intercalated with similar polyfullerene domains. Moreover, in blended films, we have found a correlation between deposition speed, the resulting microstructure, and photoluminescence quenching. The latter appeared more intense for lower deposition speeds due to a more favorable structuring at the nanoscale of the two donor and acceptor systems in the resulting blend films. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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10 pages, 3101 KiB

Open AccessArticle

Multimaterial 3D Printing for Arbitrary Distribution with Nanoscale Resolution

by Fengqiang Zhang, Changhai Li, Zhenlong Wang, Jia Zhang and Yukui Wang

Nanomaterials 2019, 9(8), 1108; https://doi.org/10.3390/nano9081108 - 2 Aug 2019

Cited by 8 | Viewed by 3409

Abstract

At the core of additive manufacturing (3D printing) is the ability to rapidly print with multiple materials for arbitrary distribution with high resolution, which can remove challenges and limits of traditional assembly and enable us to make increasingly complex objects, especially exciting meta-materials. [...] Read more.

At the core of additive manufacturing (3D printing) is the ability to rapidly print with multiple materials for arbitrary distribution with high resolution, which can remove challenges and limits of traditional assembly and enable us to make increasingly complex objects, especially exciting meta-materials. Here we demonstrate a simple and effective strategy to achieve nano-resolution printing of multiple materials for arbitrary distribution via layer-by-layer deposition on a special deposition surface. The established physical model reveals that complex distribution on a section can be achieved by vertical deformation of simple lamination of multiple materials. The deformation is controlled by a special surface of the mold and a contour-by-contour (instead of point-by-point) printing mode is revealed in the actual process. A large-scale concentric ring array with a minimum feature size below 50 nm is printed within less than two hours, verifying the capacity of high-throughput, high-resolution and rapidity of printing. The proposed printing method opens the way towards the programming of internal compositions of object (such as functional microdevices with multiple materials). Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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15 pages, 2118 KiB

Open AccessArticle

Tannic Acid-Mediated Aggregate Stabilization of Poly(N-vinylpyrrolidone)-b-poly(oligo (ethylene glycol) methyl ether methacrylate) Double Hydrophilic Block Copolymers

by Noah Al Nakeeb, Ivo Nischang and Bernhard V.K.J. Schmidt

Nanomaterials 2019, 9(5), 662; https://doi.org/10.3390/nano9050662 - 26 Apr 2019

Cited by 10 | Viewed by 5357

Abstract

The self-assembly of block copolymers in aqueous solution is an important field in modern polymer science that has been extended to double hydrophilic block copolymers (DHBC) in recent years. In here, a significant improvement of the self-assembly process of DHBC in aqueous solution [...] Read more.

The self-assembly of block copolymers in aqueous solution is an important field in modern polymer science that has been extended to double hydrophilic block copolymers (DHBC) in recent years. In here, a significant improvement of the self-assembly process of DHBC in aqueous solution by utilizing a linear-brush macromolecular architecture is presented. The improved self-assembly behavior of poly(N-vinylpyrrolidone)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (PVP-b-P(OEGMA)) and its concentration dependency is investigated via dynamic light scattering (DLS) (apparent hydrodynamic radii ≈ 100–120 nm). Moreover, the DHBC assemblies can be non-covalently crosslinked with tannic acid via hydrogen bonding, which leads to the formation of small aggregates as well (apparent hydrodynamic radius ≈ 15 nm). Non-covalent crosslinking improves the self-assembly and stabilizes the aggregates upon dilution, reducing the concentration dependency of aggregate self-assembly. Additionally, the non-covalent aggregates can be disassembled in basic media. The presence of aggregates was studied via cryogenic scanning electron microscopy (cryo-SEM) and DLS before and after non-covalent crosslinking. Furthermore, analytical ultracentrifugation of the formed aggregate structures was performed, clearly showing the existence of polymer assemblies, particularly after non-covalent crosslinking. In summary, we report on the completely hydrophilic self-assembled structures in solution formed from fully biocompatible building entities in water. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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Review

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26 pages, 5952 KiB

Open AccessReview

Recent Advances in Sequential Infiltration Synthesis (SIS) of Block Copolymers (BCPs)

by Eleonora Cara, Irdi Murataj, Gianluca Milano, Natascia De Leo, Luca Boarino and Federico Ferrarese Lupi

Nanomaterials 2021, 11(4), 994; https://doi.org/10.3390/nano11040994 - 13 Apr 2021

Cited by 21 | Viewed by 4231

Abstract

In the continuous downscaling of device features, the microelectronics industry is facing the intrinsic limits of conventional lithographic techniques. The development of new synthetic approaches for large-scale nanopatterned materials with enhanced performances is therefore required in the pursuit of the fabrication of next-generation [...] Read more.

In the continuous downscaling of device features, the microelectronics industry is facing the intrinsic limits of conventional lithographic techniques. The development of new synthetic approaches for large-scale nanopatterned materials with enhanced performances is therefore required in the pursuit of the fabrication of next-generation devices. Self-assembled materials as block copolymers (BCPs) provide great control on the definition of nanopatterns, promising to be ideal candidates as templates for the selective incorporation of a variety of inorganic materials when combined with sequential infiltration synthesis (SIS). In this review, we report the latest advances in nanostructured inorganic materials synthesized by infiltration of self-assembled BCPs. We report a comprehensive description of the chemical and physical characterization techniques used for in situ studies of the process mechanism and ex situ measurements of the resulting properties of infiltrated polymers. Finally, emerging optical and electrical properties of such materials are discussed. Full article

(This article belongs to the Special Issue Nanoscale Self-Assembly: Nanopatterning and Metrology)

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