Search results for "polymerization"
showing 10 items of 1689 documents
Nanoscale hybrid silica/polymer Janus particles with a double-responsive hemicorona
2015
Abstract We report a versatile large-scale synthesis strategy for hybrid Janus nanoparticles with a silica core and a unilaterally attached polymer corona in a size range below 100 nm. The stimuli-responsive behavior of these nanoparticles with a poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) hemicorona is investigated. The synthesis is based on a modified version of the Pickering emulsion polymerization technique in combination with surface-initiated atom transfer radical polymerization (ATRP) in a “grafting from” approach. In a first step, poly(vinyl acetate) (PVAc) latex particles are prepared via Pickering emulsion polymerization. Colloidal stability is provided by 30 nm silica nan…
Design, Synthesis, and Use of Y-Shaped ATRP/NMP Surface Tethered Initiator.
2015
Heterogeneous polymer brushes on surfaces can be easily formed from a binary initiator on a silicon oxide substrate where two different types of polymers can be grown side-by-side. Herein, we designed a new Y-shaped binary initiator using straightforward chemistry for “grafting from” polymer brushes. This initiator synthesis takes advantage of the Passerini reaction, a multicomponent reaction combining two initiator sites and one surface linking site. This Y-shaped binary initiator can be synthesized in three steps with a higher yield than other similar initiators reported in the literature, and can be performed on a multigram scale. We were able to attach the initiator to a silicon oxide s…
Temperature-Responsive Surface Coatings Based on Poly(methylsilsesquioxane)-hybrid Polymers
2007
The present paper presents a new method to build up temperature-responsive surfaces. First a poly(silsesquioxane)-block-poly(N-isopropyl-acrylamide) (PMSSQ-b-PNIPAM) was successfully synthesized using RAFT polymerization. Spin-coating or dip-coating of PMSSQ-b-PNIPAM onto glass surfaces resulted in temperature-responsive surfaces. Surface ATR FT-IR measurements proofed the successful surface modification using PMSSQ-b-PNIPAM. IR fine structures of PNIPAM and PMSSQ could be assigned, respectively. In capillary rise experiments a change of the meniscus height measured at temperatures below or above LCST was observed, indicating a different wetting behavior. Thus, a simple spin- or dip-coating…
Influence of processing conditions on some properties of anionically synthesized polycaprolactam in presence of lithium chloride
1980
Nylon 6–LiCl systems of various concentrations were prepared by anionic polymerization of caprolactam in the presence of salt. A depression of both crystallization rate and melting temperature was evidenced through x-ray, density, and DSC analyses. Such a preliminary characterization allowed for choosing the proper conditions in order to obtain amorphous fibers from a spinning operation which was performed at a temperature lower than the pure polymer melting point. These results are of technological relevance, especially in view of obtaining, as in similar cases, large amorphous orientations through a spinning–drawing process and high-modulus fibers after subsequent crystallization. Also, t…
Side-chain conjugated polymers for use in the active layers of hybrid semiconducting polymer/quantum dot light emitting diodes
2016
Three monomers, M1–M3, with modified carbazole cores and styrene functionality were prepared for use in the active layers of hybrid polymer/quantum dot light emitting diodes. Utilizing reversible addition fragmentation chain transfer polymerization, side-chain conjugated polymers, P1–P3, with narrow polydispersities and disulfide end groups were obtained. The thermal, optical, and electrochemical properties of the polymers varied depending on the substituents of the carbazole cores. Through the disulfide end groups the polymers were chemically blended with quantum dots to obtain QD/polymer hybrids, which were further used as active layers in light emitting diodes. The fabricated devices ret…
Polymeric amphiphiles with hydrophilic main chain spacers: Studies in monolayers and Langmuir-Blodgett multilayers
1988
A methacrylic lipid was polymerized to form an amphiphilic homopolymer and random copolymers with various levels of acrylic acid comonomers. The behavior of these polymeric lipids was investigated in monolayers at the air-water interface and in Langmuir-Blodgett multilayers on polymer foil supports. The acrylic acid acts as a hydrophilic spacer along the polymer backbone, and improves the ability of the polymer to self-organize into highly ordered monolayers and ultimately LB multilayers. It is shown that the quality and stability of the multilayers increase substantially with the increase in comonomer content.
Cyclodextrins in polymer synthesis: free radical polymerization of cyclodextrin complexes with oxazoline-functionalized vinyl monomers as guest molec…
2000
The synthesis of five new oxazoline functionalized vinyl monomers N-[4-(4′,5′-dihydrooxazol-2-yl)phenyl]acrylamide (3 a), N-[4-(4′,5′-dihydrooxazol-2-yl)phenyl]-2-methylacrylamide (3 b), N-{10-[4-(4′,5′-dihydrooxazol-2-yl)phenylcarbamoyl]decyl}-2-acrylamide (5 a), N-{10-[4-(4′,5′-dihydrooxazol-2-yl)phenylcarbamoyl]decyl}-2-methylacrylamide (5 b) and N-[4-(4′,5′-dihydrooxazol-2-yl)-phenyl]-4-vinylbenzamide (7) is described. With an equimolar amount of 2,6-dimethyl-β-cyclodextrin (DMCD) these monomers formed hydrophilic inclusion complexes 3 a,b-DMCD, 5 a,b-DMCD and 7-DMCD. These complexes were polymerized radically in an aqueous medium. Resulting polymers P-(3 a, b), P-(5 a, b) and P-(7) pre…
Hyperbranched-linear-hyperbranched ABA-type block copolymers based on poly(ethylene oxide) and polyglycerol
2009
BACKGROUND: Until recently, hyperbranched polymers were thought to be ill-defined materials that were not useful as building blocks for well-defined complex polymer architectures. It is a current challenge to develop strategies that offer rapid access to well-defined hyperbranched block copolymers. RESULTS: A convenient three-step protocol for the synthesis of double-hydrophilic hyperbranched–linear–hyperbranched ABA-type triblock copolymers based on poly(ethylene oxide) (PEO) and hyperbranched polyglycerol (hbPG) is presented. The Bola-type polymers exhibiting an aliphatic polyether structure were prepared from a linear (lin) linPG-b-PEO-b-linPG precursor triblock. The materials exhibit lo…
Artificial Opals as Effect Pigments in Clear-Coatings
2004
In this paper, we describe the use of artificial opals from polymer beads as effect pigments in transparent industial and automotive coatings. For this purpose, we synthesized monodisperse colloids from fluorinated methacrylates by surfactant-free emulsion polymerization. The fluorinated monomers, in combination with crosslinking, lead to a refractive index contrast, thermal stability, and solvent resistivity necessary for use as effect pigments. After crystallization of the monodisperse polymer beads, crystal flakes with iridescent colors can be obtained. The crystal flakes can act as effect pigments in various transpartent industrial and automotive coatings. due to photonic crystal behavi…
Architecture, self-assembly and properties of well-defined hybrid polymers based on polyhedral oligomeric silsequioxane (POSS)
2013
Abstract Well-defined hybrid polymers based on polyhedral oligomeric silsequioxane (POSS) with a variety of architectures have been developed, including telechelic polymers, block copolymers and star-shaped polymers. The synthesis, self-assembly and properties of this kind of materials are reviewed. Well-defined POSS-containing hybrid polymers can be constructed by living polymerization techniques, such as ring-opening polymerization and living free-radical polymerization or the combination of living polymerization and coupling reactions, such as click chemistry and hydrosilylation. The self-assembly behavior of well-defined POSS-containing hybrid polymers is also described in detail. The P…