Structural Investigations on Hybrid Polymers Suitable as a Nanoparticle Precipitation Environment (original) (raw)
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Versatile Hybrid Polymers as Matrices for Nanoparticle Preparation
MRS Proceedings, 2007
ABSTRACTHybrid inorganic-organic polymers were prepared applying poly(ethylene oxide) (PEO) crosslinked polysiloxanes as a matrix for the precipitation of metal or metal oxide nanoparticles. Polysiloxanes as flexible and hydrophobic polymer backbones were crosslinked with end-group functionalized PEO by using Pt-catalyzed hydrosilation reactions. Systematic variation of the chain length of the different components resulted in tunable matrices with adjustable hydrophilic regions. The chemical nature of the polysiloxane backbone and the thermal stability of the crosslinked polymer system facilitated nanoparticle preparation through different mechanisms.The crosslinked hybrid polymers were infiltrated with solutions of lanthanide salts, cobalt carbonyl or HAuCl4 allowing the application of three different chemical methods (hydrolysis, thermal decomposition, reduction) for nanoparticle preparation. FT-IR, SEM and TEM analyses were used to characterize the insoluble hybrid systems.
Nanostructured hybrid materials from aqueous polymer dispersions
Advances in Colloid and Interface Science, 2004
Organic-inorganic (O-I) hybrids with well-defined morphology and structure controlled at the nanometric scale represent a very interesting class of materials both for their use as biomimetic composites and because of their potential use in a wide range of technologically advanced as well as more conventional application fields. Their unique features can be exploited or their role envisaged as components of electronic and optoelectronic devices, in controlled release and bioencapsulation, as active substrates for chromatographic separation and catalysis, as nanofillers for composite films in packaging and coating, in nanowriting and nanolithography, etc. A synergistic combination or totally new properties with respect to the two components of the hybrid can arise from nanostructuration, achieved by surface modification of nanostructures, self-assembling or simply heterophase dispersion. In fact, owing to the extremely large total surface area associated with the resulting morphologies, the interfacial interactions can deeply modify the bulk properties of each component. A wide range of starting materials and of production processes have been studied in recent years for the controlled synthesis and characterization of hybrid nanostructures, from nanoparticle or lamellar dispersions to mesoporous materials obtained from templating nanoparticle dispersions in a continuous, e.g. ceramic precursor, matrix. This review is aimed at giving some basic definitions of what is intended as a hybrid (O-I) material and what are the main synthetic routes available. The various methods for preparing hybrid nanostructures and, among them, inorganic-organic or O-I core-shell nanoparticles, are critically analyzed and classified based on the reaction medium (aqueous, non-aqueous), and on the role it plays in directing the final morphology. Particular attention is devoted to aqueous systems and water-borne dispersions which, in addition to being environmentally more acceptable or even a mandatory choice for any future development of large output applications (e.g. in paint, ink and coating industry), can provide the thermodynamic drive for self-assembling of amphiphilics, adsorption onto colloidal particles or partitioning of the hybrid's precursors between dispersed nanosized reaction loci, as in emulsion or miniemulsion free-radical polymerization. While nanoencapsulation and self-assembling processes are already exploited as commercially viable fabrication methods, a newly developed technique based on two-stage sol-gel and freeradical emulsion polymerization is described, which can grant a versatile synthetic approach to hybrid O-I nanoparticles with tailor-made composition of both the organic core and the silica or organosilica shell, and good control on morphology, size and heterophase structure in the 50-500 nm range. Styrene or acrylate homo-and copolymer core latex particles need to be modified with a reactive comonomer, such as trimethoxysilylpropyl methacrylate, to achieve efficient interfacial coupling with the inorganic shell. Accurate control over pH and process conditions is required to avoid latex coagulation or, in case of organic particles with uniform composition, incipient intraparticle crosslinking. ᮊ
Hybrid Polymer Particles with a Protective Shell: Synthesis, Structure, and Templating
Chemistry of Materials, 2006
The development of hybrid polymer particles formed by the hydrolytic condensation of octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride (ODMACl) and the trisodium salt of the triacetic acid N-(trimethoxysilylpropyl)ethylenediamine (TANED) along with self-assembling with nonionic poly-(ethylene glycol) (PEG) based surfactants containing a hydrophobic octadecyl tail (Brij) have been studied using liquid and solid-state NMR, dynamic light scattering (DLS), transmission electron microscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and small-angle X-ray scattering (SAXS). On the basis of DLS and NMR data, the mechanism of interaction of Brij, ODMACl, and TANED molecules in an aqueous solution has been suggested. The influence of the PEG chain length on the ability of surfactants to stabilize polymer particles has been established. The combination of DSC and XRD assessed the crystallinity and thermal properties of self-assembled hybrid materials in the solid state, while SAXS studies revealed that their morphology strikingly depends on the PEG chain length and reaction conditions determining the degree of Brij incorporation and the structure of the Brij-ODMACl complex. Because of the protective PEG shell, the hybrid polymer particles were successfully used as soluble templates for the formation of iron oxide nanoparticles.
Journal of Colloid and Interface Science, 2002
Hydrophobically modified poly(ethylene oxide), HMPEO, was studied in concentrated salt solutions. The influence of salts was compared to the effect of temperature on poly(ethylene oxide), PEO. As expected, the addition of monovalent cations (Na + , K +) has the same effect as an increase in temperature in agreement with the thermodynamic properties of PEO: a decrease in solubility, micelle size, and viscosity was observed. Moreover, the intensity of neutron scattering peaks (characteristic of the semi-dilute solutions of these associative polymers) increases due to the collapse of PEO coronae in micelles. Very peculiar behavior was observed in the presence of divalent cations (Ca 2+ , Mg 2+): larger micelle aggregates and higher viscosities, relaxation times, and activation energies were observed by dynamic rheology. This behavior is attributed to interactions between divalent cations and oxygen in PEO backbones close to the micelle core, which may reinforce intermicellar bridges.
Analysis of the structure of polymer-inorganic nanoparticles in solutions
Nanotechnologies in Russia, 2014
A methodical approach to analyzing the structure of hybrid polymer inorganic particles with cov alent bonding between the components has been suggested. Its effectiveness has been demonstrated on the example of modified poly(methyl methacrylate) containing covalently bonded zirconium dioxide nanocrys tals. The methodological approach is based on the application of viscometry, dynamic light scattering, and absorption spectroscopy for a comparative study of the unmodified polymer and its analogue containing a low weight fraction (about a few hundredths) of hybrid particles. The methodology allows a quantitative estima tion of the weight of the polymer component covalently bonded to the inorganic nanoparticle to obtain a fully soluble composite material.
Journal of Scientific Research, 2017
This investigation described a simple three-step process for the fabrication of micrometersized magnetic composite polymer particles. This composite polymer particle consisted of crosslinked hydrophobic poly(lauryl methacrylate-divinyl benzene) (P(LMA-DVB)) core, prepared by suspension polymerization. Then, P(LMA-DVB) copolymer core particles were coated with poly(glycidyl methacrylate) (PGMA) by seeded polymerization to introduce epoxide functionality. Finally, P(LMA-DVB)/PGMA composite particles were doped with iron oxide (Fe 3 O 4) nanoparticles following in situ co-precipitation of Fe 2+ and Fe 3+ from their alkali aqueous solution. The presence of strained oxirane ring derived from PGMA segment present at the surface is expected to induce high affinity towards precipitated magnetic Fe 3 O 4 nanoparticles. The compositional structure of P(LMA-DVB)/PGMA/Fe 3 O 4 composite polymer particles was confirmed by Fourier Transform IR (FTIR), electron microscopy, thermogravimetry (TG), X-ray diffraction (XRD) and energydispersive X-ray (EDX).
Macromolecular Chemistry and Physics, 2012
A facile and versatile synthetic route for controlling the size and surface potential of silicapolyethylenglycol hybrid nanoparticles (silica@PEG) is introduced in this paper. Two different types of spherical, organic-inorganic hybrid silica nanoparticles have been prepared by using polyethyleneglycol methyl ether-3-(triethoxysilyl) propyl urethane (mPEG-IPTES) as a precursor. By grafting the precursor to pristine silica, core-shell nanoparticles were obtained, while direct condensation of the precursor with TEOS lead to bulk hybrid nanoparticles. The resulting nanoparticles were characterized by TEM, DLS, TGA, FTIR, and laser Doppler electrophoresis proving that all silica@PEG present suppressed BSA adsorption while the size and charge can be controlled by the concentration of added precursor. Results presented here may have major implications in biomedical and colloidal chemistry since interfacial and colloidal properties are known to drive several processes associated with nanoparticles (NPs) in biological media like toxicity, biopersistence, cell adhesion and internalization.