Search results for "polymerization"
showing 10 items of 1689 documents
Towards completely miscible PMMA nanocomposites reinforced by shear-stiff, nano-mica
2014
Abstract Optimizing the reinforcement of polymers with nanoplatelets requires optimization of the aspect ratio and the moduli of the filler while providing a complete stress transfer. Employing a novel shear-stiff, nano-mica with large aspect ratio, we focus on maximizing the interfacial interaction between filler and matrix. External surfaces of the nano-mica were selectively modified by a polycationic macro-initiator and two PMMA-polymer brushes of length below and above critical entanglement length, respectively, and the mechanical properties of the three PMMA nanocomposites were measured. The multiple electrostatic anchoring groups of the macro-initiator not only provide reliable adhesi…
Effect of elongational flow on morphology and properties of polymer/CNTs nanocomposite fibers
2010
Carbon nanotubes (CNTs) have been attracting increasing interest for the fabrication of polymer-based nanocomposites because of their excellent properties. Traditional methods for the preparation of polymer/CNTs nanocomposites are in situ polymerization, solution blending, and melt mixing. The achievement of a good CNT dispersion and a percolation network is important in order to obtain better mechanical and electrical properties. However, the rheological behavior of polymer/CNTs systems, in particular regarding the extensional flow, has not been much investigated so far. In this work we present, for the first time, rheological data in non-isothermal extensional flow and an investigation on…
Liquid crystalline phases from polymer functionalized ferri-magnetic Fe3O4nanorods
2017
Here, we present the surface functionalization of anisotropic in form ferri-magnetic Fe3O4-nanorods (NRs) with a diblock copolymer, having a PMMA- or PDEGMEMA-block, for solubilization, and a dopamine anchor block. These polymers were synthesized through RAFT polymerization via a macro-initiator approach. The successful surface functionalization, performed via a grafting-to method, was monitored using TGA, IR and TEM measurements. The NRs were very soluble in organic solvents after functionalization. Afterwards, the liquid crystalline (LC) behavior was investigated. During solvent evaporation, birefringent domains were formed. The self-assembly into lyotropic LC structures could be observed…
Application of Nanoemulsions in the Synthesis of Nanoparticles
2018
Abstract Nanodroplets of a liquid in another immiscible liquid provide confined spaces in which chemical reactions can take place. If these reactions lead to the formation of nanoparticles, as it is the case for polymerization or precipitation reactions, nanodroplets can be used as templates for particle synthesis. The most common example of application of nanoemulsions for particle synthesis is the preparation of polymer nanoparticles by miniemulsion polymerization, but also inorganic materials can be produced in this way. Nanoemulsions are as well an excellent platform for preparing polymer/inorganic hybrid nanoparticles, either by using directly the templating effect of droplets during t…
Luminescent and Magnetoresponsive Multifunctional Chalcogenide/Polymer Hybrid Nanoparticles
2013
Cadmium sulfide/magnetite/polymer multifunctional hybrid nanoparticles are prepared by crystallizing CdS in a controlled manner on the surface of phosphonate-functionalized polystyrene particles with a magnetic core. The supporting polymer magnetoresponsive nanoparticles are produced by a modified miniemulsion polymerization process: a first miniemulsion containing the core monomer (styrene) and a phosphonate-functionalized surface-active monomer is mixed with a second miniemulsion containing magnetite nanoparticles capped with oleic acid and the same surface-active monomer. The chalcogenide formation occurs in situ at the surface of the polymer particles by adding a precipitating agent (so…
Living Anionic Polymerization in Continuous Flow: Facilitated Synthesis of High-Molecular Weight Poly(2-vinylpyridine) and Polystyrene
2014
We describe the living anionic polymerization of 2-vinylpyridine (2VP) and styrene (S) in continuous flow, comparing two micromixing devices with different mixing principles. The use of a continuous flow setup reduces the experimental effort for living anionic polymerizations significantly, compared to a conventional batch system. By adjusting the ratio of the flow rates of the monomer and initiator solutions a variety of different molecular weights can be rapidly synthesized within several minutes, using one setup. Additionally, a comparison of the influence of the two different mixing devices—an interdigital micromixer (SIMM-V2) leading to laminar mixing and a tangential four-way jet mixi…
UV optical record and electron beam lithography in polymer films
2012
Possibility of UV optical record and electron beam lithography in different type of organic polymer films was studied. Mechanisms of molecular structure changes: photoisomerization, destruction, cross-linking and oxidation have been discussed. The results of UV illumination of polyurethanes, polyacrilates, and some block-copolymers are described. The element analysis of polyisoprene block copolymer was performed before and after UV illumination, and the changes in transmission spectra of the polymer film were measured. The resolution of electron beam lithography on polymer films was studied. In the polyisoprene block copolymer film the oxidation polymerization was ascertain at UV-illuminati…
<title>Effect of light exposure on dislocation mobility in fullerite C60 crystals</title>
2001
The illumination-time evolution and the wavelength dependence of the photoinduced changes in dislocation mobility on the (111) face of C60 single crystals in air for the wavelength range 150 - 900 nm and power densities 0.2 - 2 mW/cm2 has been investigated. The results show that the light exposure in air leads to the decrease of the dislocation mobility. The magnitude of the effect as a function of the illumination time was investigated and a two-stage relationship was obtained. The ultraviolet light was found to be more effective than the visible light in the photoinduced reduction of dislocation mobility and solubility. In the wavelength range of 150 - 700 nm, the reduction of dislocation…
Polymerization of mono- and multilayer forming diacetylenes
1977
Heptadeca-2,4-diine-1-ol and Heptadeca-2,4-diine-1-acid were synthesized and their polymerization behaviour in the solid state was investigated. Both compounds polymerize thermally below the melting point and photochemically under the action of uv-light to form polymers via 1,4-addition to the conjugated triple bonds with a backbone of conjugated double-and triple-bonds. The photoresponse spectra resemble the absorption spectra exhibiting maxima of photoreactivity in the absorption band of the conjugated triple bonds of the monomers.
Synthesis of Processable Inorganic‐Organic Hybrid Polymers Based on Poly(silsesquioxanes): Grafting from Polymerization Using ATRP
2008
Inorganic-organic hybrid polymers have been synthesized utilizing atom transfer radical polymerization (ATRP) from a functionalized poly(methylsilsesquioxane) (PMSSQ) macroinitiator. Different polymeric ATRP initiators were prepared by co-condensation of functionalized trichlorosilanes with methyltrimethoxysilane. Various vinyl monomers have been successfully grafted from these macroinitiators, demonstrating a highly variable synthetic concept, which offers the chance to synthesize a wide spectrum of inorganic-organic hybrid polymers. All synthesized polymers were soluble in various organic solvents. Spin-coating these hybrid materials onto various substrates could produce stable and adhere…