Search results for "copolymer"
showing 10 items of 1003 documents
In Silico Design Enables the Rapid Production of Surface-Active Colloidal Amphiphiles
2020
A new technology platform built on the integration of theory and experiments to enable the design of Janus colloids with precision control of surface anisotropy and amphiphilicity could lead to a disruptive transformation in the next generation of surfactants, photonic or phononic materials, and coatings. Here, we exploit molecular dynamics (MD) simulations to guide the rational design of amphiphilic polymer Janus colloids by Flash NanoPrecipitation (FNP), a method capable of the production of colloids with complex structure without the compromise of reduced scalability. Aided by in silico design, we show in experiments that amphiphilic Janus colloids can be produced using a unique blend of…
Chemically Fueled Block Copolymer Self‐Assembly into Transient Nanoreactors**
2021
In chemically fueled supramolecular materials, molecular self-assembly is coupled to a fuel-driven chemical reaction cycle. The fuel-dependence makes the material dynamic and endows it with exciting properties like adaptivity and autonomy. In contrast to the large work on the self-assembly of small molecules, we herein designed a diblock copolymer, which self assembles into transient micelles when coupled to a fuel-driven chemical reaction cycle. Moreover, we used these transient block copolymer micelles to locally increase the concentration of hydrophobic reagents and thereby function as a transient nanoreactor.
Nonionic Aliphatic Polycarbonate Diblock Copolymers Based on CO2, 1,2-Butylene Oxide, and mPEG: Synthesis, Micellization, and Solubilization
2019
Carbon dioxide (CO2) is a renewable carbon source that is easily available in high purity and is utilized as a co-monomer in the direct ring-opening polymerization of epoxides to obtain aliphatic polycarbonates. In this work, degradable aliphatic polycarbonate diblock copolymers (mPEG- b-PBC) are synthesized via catalytic copolymerization of CO2 and 1,2-butylene oxide, starting from monomethoxy poly(ethylene glycol) (mPEG) as a chain transfer reagent. The polymerization proceeds at low temperatures and high CO2 pressure, utilizing the established binary catalytic system ( R, R)-Co(salen)Cl/[PPN]Cl. Amphiphilic nonionic diblock copolymers with varying PBC block lengths and hydrophilic-lipoph…
Robust Mesoporous CoMo/γ-Al2O3 Catalysts from Cyclodextrin-Based Supramolecular Assemblies for Hydrothermal Processing of Microalgae: Effect of the P…
2018
Hydrothermal liquefaction (HTL) is a promising technology for the production of biocrude oil from microalgae. Although this catalyst-free technology is efficient under high-temperature and high-pressure conditions, the biocrude yield and quality can be further improved by using heterogeneous catalysts. The design of robust catalysts that preserve their performance under hydrothermal conditions will be therefore very important in the development of biorefinery technologies. In this work, we describe two different synthetic routes (i.e., impregnation and cyclodextrin-assisted one-pot colloidal approach), for the preparation in aqueous phase of six high surface area CoMo/γ-Al2O3 catalysts. Cat…
NANOPARTICLES BASED ON NOVEL AMPHIPHILIC POLYASPARTAMIDE COPOLYMERS
2010
In this article, the synthesis of two amphiphilic polyaspartamide copolymers, useful to obtain polymeric nanoparticles without using surfactants or stabilizing agents, is described. These copolymers were obtained starting from α,β-poly-(N-2-hydroxyethyl)-dl-aspartamide (PHEA) by following a novel synthetic strategy. In particular, PHEA and its pegylated derivative (PHEA-PEG2000) were functionalized with poly(lactic acid) (PLA) through 1,1′-carbonyldiimidazole (CDI) activation to obtain PHEA–PLA and PHEA-PEG2000–PLA graft copolymers, respectively. These copolymers were properly purified and characterized by 1H-NMR, FT-IR, and Size Exclusion Chromatography (SEC) analyses, which confirmed that…
Photocatalytic printing of inorganic nanopatterns via poly(styrene-block-carbosilane) copolymer thin films on titania substrates.
2009
Well-defined, ordered arrays of nanoscale depressions were obtained in linear-brush-type polystyrene-block-polycarbosilane (PS-b-PCS) diblock copolymer thin films by acetone vapor annealing and silica nanodot arrays were directly obtained from such thin films deposited on a titania substrate by one-step exposure to UV light as a result of transformation of the PCS units to silica, driven by the photocatalytic activity of titania concurrent with removal of the organic matrix.
Synthesis and characterisation of ordered arrays of mesoporous carbon nanofibres
2009
A facile and reproducible one-step pathway has been developed for preparing ordered arrays of mesoporous carbon nanostructures within the pores of anodized aluminium oxide (AAO) membranes, through the confined self-assembly of phenol/formaldehyde resol and amphiphilic copolymer templates. The morphology of the mesoporous carbon nanostructures can be controlled by varying the copolymer surfactant, the quantity of the resol–surfactant precursor sol used and the amount of phenol–formaldehyde resol introduced into the resol–surfactant sol. One-dimensional (1-D) carbon nanostructures, such as carbon fibres with a core–shell structure and carbon ribbons with circular mesopores running parallel to…
Characterizing the Glassy Phase of a Statistical Copolymer Monolayer
1999
Monolayers of a statistical copolymer with a poly(methacrylate) chain and hydrophilic and hydrophobic side groups are investigated at the air/water interface. The isotherms suggest a fluid and a frozen phase. With in-situ X-ray reflectivity the monolayer thickness is determined to be 2.5 nm or less. The shear viscosity in the fluid phase is extremely high yet can be described in the framework of the free area model. However, the parameter which characterizes the overlap of holes available for a diffusing monomer unit is a factor of 2 higher than expected, suggesting local diffusion barriers formed by nanosized clusters. In the glassy phase single-molecule fluorescence shows anomalous diffus…
Nanoparticles Built of Cross-Linked Heterotelechelic, Amphiphilic Poly(dimethylsiloxane)-b-poly(ethylene oxide) Diblock Copolymers
2000
Novel short chain α,ω-heterotelechelic amphiphilic poly(dimethylsiloxane)-b-poly(ethylene oxide) diblock copolymers (PDMS−PEO) with total molecular weights below 10 000 g/mol are synthesized, characterized, and used as basic constituent parts for functionalized nanoparticles. The self-assembly of the amphiphilic diblock copolymer in water as a solvent selective for the PEO block leads to the formation of spherical and cylindrical micellar structures with diameters between 10 and 25 nm. The core of the micelles is built of the hydrophobic PDMS chains, whereas the corona is set up by the hydrophilic PEO blocks. By using α,ω-heterotelechelic diblock copolymers, it is possible to fix the core o…
Porphyrin Antenna-Enriched BODIPY–Thiophene Copolymer for Efficient Solar Cells
2018
International audience; Low bandgap A−π–D copolymer, P(BdP-DEHT), consisting of alternating BOronDIPYrromethene (BODIPY) and thiophene units bridged by ethynyl linkers, and its porphyrin-enriched analogue, P(BdP/Por-DEHT), were prepared, and their optical and electrochemical properties were studied. P(BdP-DEHT) exhibits strong absorption in the 500–800 nm range with an optical bandgap of 1.74 eV. On the basis of cyclic voltammetry, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are evaluated to be −5.40 and −3.66 eV, respectively. After the anchoring of zinc(II) porphyrin on the BODIPY unit, P(BdP/Por-DEHT) displays broadened absor…