Colloidal polymers from inorganic nanoparticle monomers

Abstract

The use of preformed inorganic nanoparticles as "colloidal monomers" has received recent attention for the formation of one-dimensional (1-D) mesostructures, or "colloidal polymers." These colloidal monomers form linear assemblies through attractive, directional, interparticle interactions, which are similar to covalent or supramolecular interactions in classical polymer science. However, in contrast to the high degree of structural control available in the synthesis of classical molecular polymers, methods to control fundamental structural features such as chain length (DP), composition (copolymers), and architecture (linear, branched, etc.) are still being developed for NP-based colloidal polymer systems. We therefore review the colloidal polymerization of inorganic nanoparticle monomers by applying the conceptual framework provided by polymer science to categorize these novel systems. The descriptive nomenclature used for classical polymers is applied to NP assembly to define more explicitly the types of colloidal polymers formed in terms of DP, architecture, and composition (for binary NP assemblies). This Review includes descriptions of inorganic nanoparticle types useful for the formation of colloidal polymers with examples chosen to demonstrate control over mesoscopic structure and composition. The various emergent optical, electrical and electrochemical properties from these materials are also reviewed and correlated with structural control achieved in various colloidal polymer systems.

Uniform decoration of Pt nanoparticles on well-defined CdSe tetrapods and the effect of their Pt cluster size on photocatalytic H2generation

“…During the Pt-tipping reaction with CdSe@CdS nanorods, when the reaction time for Pt to nucleate and grow was kinetically suppressed, only one Pt tip or no tip was observed by normal TEM, called the "activated" CdSe@CdS nanorods. 5,6,32 Followed by the growth of second metal nanoparticles, which in this case were cobalt, the existence of Pt nanoparticles was indirectly confirmed since cobalt nanoparticles were only formed epitaxially when Pt tips were first introduced to the ends of CdSe@CdS nanorods. 33 Control experiment was performed by growing cobalt nanoparticles in the presence of bare CdSe tetrapods synthesized by the CPI approach and Pt-decorated CdSe tetrapods with an extremely low amount of Pt precursors ( Figure S2).…”

Laser generated gold nanocorals with broadband plasmon absorption for photothermal applications

“…6,9 In particular, by increasing the aspect ratio of nanorods, the second SPR can be shifted from the visible to the near infrared (NIR) range. [11][12][13] For instance, networks of partially fused gold nanoparticles showed very low-energy surface plasmon modes capable of supporting long-range and spectrally tunable propagation in nanoscale waveguides. 6,8 Recently, asymmetric networks of gold nanoparticles have been proposed as an interesting system to obtain versatile and multimodal plasmonic responses.…”

“…26 For instance, NIR absorbing nanoparticles are exploitable as sensitizers for photothermal therapy, which is based on the occurrence of protein denaturation and cellular membrane disruption, with initiation of apoptotic mechanisms, when tissues temperature exceeds 42 -44 °C. 3,12,21,[30][31][32] For instance, surface functionalization is required for the colloidal stability in biological fluids or in liquid solution, 3, 33 the inclusion in polymeric matrixes, 19, 21 the addition of selectivity versus target biomolecules or other chemical species, 3,30 and the formation of surface patterns with multiple applications. 27 Besides, NIR absorbers are exploitable as contrast agents for photoacoustic imaging, which is rapidly emerging as a promising highresolution technique for optical visualization of tissues.…”

“…54,56,59 At the fluence of 1300 mJ/cm 2 used in the present work, both mechanisms take place simultaneously, yielding small Au nanoparticles. 12,15,60,61 However, a satisfactory quantitative description of their formation mechanism is lacking at the moment, and only few recent reports considered Brownian dynamics simulations to model the aggregation of nanoparticles in liquid environment. Instead, AuNC forms after photofragmentation, by unidirectional coalescence and reorganization of Au fragments.…”

Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

“…For example, densely grafted chains can generate effective steric repulsions between colloidal particles and thereby prevent flocculation; 8 grafted-chain-driven associations can direct the assembly of nanoparticles into colloidal polymers or networks. 9 In biosystems, the lipid tails in the membrane form a typical structure of brush; arrays of cilia are also of brush-like structure but of much larger size (micrometer) than the conventional molecular brush. 10,11 Many efforts have been made to reveal and understand the equilibrium properties of polymer brush.…”