8 research outputs found
Ordering of Polystyrene Nanoparticles on Substrates Pre-Coated with Different Polyelectrolyte Architectures
Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate
Article Ordering of Polystyrene Nanoparticles on Substrates Pre-Coated with Different Polyelectrolyte Architectures
Abstract: Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate. Int. J. Mol. Sci. 2013, 14 1289
Ordering of Polystyrene Nanoparticles on Substrates Pre-Coated with Different Polyelectrolyte Architectures
Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate
Stimuli-Responsive Polyelectrolyte Brushes As a Matrix for the Attachment of Gold Nanoparticles: The Effect of Brush Thickness on Particle Distribution
The effect of brush thickness on the loading of gold nanoparticles (AuNPs) within stimuli-responsive poly-(N,N-(dimethylamino ethyl) methacrylate) (PDMAEMA) polyelectrolyte brushes is reported. Atom transfer radical polymerization (ATRP) was used to grow polymer brushes via a âgrafting fromâ approach. The brush thickness was tuned by varying the polymerization time. Using a new type of sealed reactor, thick brushes were synthesized. A systematic study was performed by varying a single parameter (brush thickness), while keeping all other parameters constant. AuNPs of 13 nm in diameter were attached by incubation. X-ray reflectivity, electron scanning microscopy and ellipsometry were used to study the particle loading, particle distribution and interpenetration of the particles within the brush matrix. A model for the structure of the brush/particle hybrids was derived. The particle number densities of attached AuNPs depend on the brush thickness, as do the optical properties of the hybrids. An increasing particle number density was found for increasing brush thickness, due to an increased surface roughness
Stimuli-Responsive Polyelectrolyte Brushes As a Matrix for the Attachment of Gold Nanoparticles: The Effect of Brush Thickness on Particle Distribution
The effect of brush thickness on the loading of gold nanoparticles (AuNPs) within stimuli-responsive poly-(N,N-(dimethylamino ethyl) methacrylate) (PDMAEMA) polyelectrolyte brushes is reported. Atom transfer radical polymerization (ATRP) was used to grow polymer brushes via a âgrafting fromâ approach. The brush thickness was tuned by varying the polymerization time. Using a new type of sealed reactor, thick brushes were synthesized. A systematic study was performed by varying a single parameter (brush thickness), while keeping all other parameters constant. AuNPs of 13 nm in diameter were attached by incubation. X-ray reflectivity, electron scanning microscopy and ellipsometry were used to study the particle loading, particle distribution and interpenetration of the particles within the brush matrix. A model for the structure of the brush/particle hybrids was derived. The particle number densities of attached AuNPs depend on the brush thickness, as do the optical properties of the hybrids. An increasing particle number density was found for increasing brush thickness, due to an increased surface roughness
Brush/Gold Nanoparticle Hybrids: Effect of Grafting Density on the Particle Uptake and Distribution within Weak Polyelectrolyte Brushes
The effect of the brush grafting
density on the loading of 13 nm
gold nanoparticles (AuNPs) into stimuli-responsive polyÂ(<i>N</i>,<i>N</i>-(dimethylamino ethyl) methacrylate) (PDMAEMA)
brushes anchored to flat impenetrable substrates is reported. Atom-transfer
radical polymerization (ATRP) is used to grow polymer brushes via
a âgrafting fromâ approach from a 2-bromo-2-methyl-<i>N</i>-(3-(triethoxysilyl) propyl) propanamide (BTPAm)-covered
silicon substrate. The grafting density is varied by using mixtures
of initiator and a âdummyâ molecule that is not able
to initiate polymerization. A systematic study is carried out by varying
the brush grafting density while keeping all of the other parameters
constant. X-ray reflectivity is a suitable tool for investigating
the spatial structure of the hybrid, and it is combined with scanning
electron microscopy and UV/vis spectroscopy to study the particle
loading and interpenetration of the particles within the polymer brush
matrix. The particle uptake increases with decreasing grafting density
and is highest for an intermediate grafting density because more space
between the polymer chains is available. For very low grafting densities
of PDMAEMA brushes, the particle uptake decreases because of a lack
of the polymer matrix for the attachment of particles. The structure
of the surface-grafted polymer chains changes after particle attachment.
More water is incorporated into the brush matrix after particle immobilization,
which leads to a swelling of the polymer chains in the hybrid material.
Water can be removed from the brush by decreasing the relative humidity,
which leads to brush shrinking and forces the AuNPs to get closer
to each other