Hybrid Copolymers Research Articles

Nanocomposites through copolymerization of a polyhedral oligomeric silsesquioxane and methyl methacrylate

AbstractThe mechanical properties and thermal stability of polymers can be enhanced through the formation of nanocomposites. Nanocomposites consisting of hybrid copolymers of methacrylcyclohexyl polyhedral oligomeric silsesquioxane (POSS‐1) and methyl methacrylate (MMA) with up to 92 wt % (51 mol %) POSS‐1 and with superior thermal properties were synthesized using solution polymerization. The POSS‐1 contents of the copolymers were similar to or slightly higher than those in the feeds, the polydispersity indices were relatively low, and the degree of polymerization decreased with increasing POSS‐1 content. POSS‐1 enhanced the thermal stability, increasing the degradation temperature, reducing the mass loss, and preventing PMMA‐like degradation from propagating along the chain. The mass loss was reduced in a high POSS‐1 content copolymer since the polymerization of POSS‐1 with itself reduced sublimation. Exposure to 450 °C produced cyclohexyl‐POSS‐like remnants in the POSS‐1 monomer and in all the copolymers. The degradation of these remnants, for the copolymers and for the POSS‐1 monomer, yielded 75% SiO2 and an oxidized carbonaceous residue. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4264–4275, 2007

Syntheses and Electronic Behaviors of Networked Alternating Aluminum-organic Moiety Hybrid Copolymers

Hybrid copolymers with aluminum-organic moiety frameworks were successfully prepared by reacting aluminum tri-sec-butoxide with several organic diols. The compositions of the resulting copolymers were determined using IR spectroscopy, ICP, elemental analysis and CP/MASS 13C-NMR spectroscopy. The UV-VIS spectra of the copolymers were also obtained. ESR spectral examinations of the copolymers and ab-initio calculations of the copolymer models indicate that an electron transfer takes place from the organic moiety to the aluminum atom in the framework.

Self-assembly of nanostructured [MoS42−]-copolymer hybrids by solvent evaporation induction

Nanostructured [MoS42−]-copolymer inorganic-organic hybrids were synthesized by solvent evaporation-induced self-assembly approach, using nonionic triblock copolymer of P123 as the template and a single inorganic source of (NH4)2MoS4 dissolved in the mixture of formamide and H2O. The morphology and structure of the products were investigated by XRD, SEM, and TEM. The thick film prepared by the natural evaporation of solvent in air has low ordered hexagonal mesostructure with unit-cell parameter of about 94Å. The nanofilm prepared by the spin-coating technique shows well ordered hexagonal mesostructure with unit-cell parameter of about 114Å. The prepared nanostructured [MoS42−]-copolymer film shows the absorption shifting to the short wavelength in comparison to the pure (NH4)2MoS4 powders due to the formation of Mo–O bonding.

Electronic properties of calcined materials from a scandium-O-phenylene-O-yttrium-O-phenylene hybrid copolymer

Calcination of a scandium-O-phenylene-O-yttrium-O-phenylene hybrid copolymer under an argon atmosphere at 400–800 °C was performed. The calcined materials were found to be composed of nano-sized Sc2O3 and Y2O3 particles in the matrix of carbon clusters. ESR spectral examinations of the calcined materials suggest that a two-step electron transfer of Y2O3 → carbon clusters → Sc2O3 → carbon clusters took place to provide a photo-responsive oxidation–reduction function with an oxidation site at Y2O3 particles and a reduction site at carbon clusters.

Syntheses and electronic behaviors of net-worked, alternating hafnium-organic moiety hybrid copolymers

Hafnium-organic moiety hybrid copolymers were prepared by reacting hafnium n-butoxide with organic diols. ESR spectral examinations of copolymers and ab-initio calculations of copolymer models suggest that an electron transfer from organic group to hafnium atom takes place.

Synthesis of poly(acrylic acid)‐block‐poly(L‐valine) hybrid through combined atom transfer radical polymerization, click chemistry, and nickel‐catalyzed ring opening polymerization methods

AbstractA new hybrid amphiphilic system between a polyacrylic acid (PAA) synthetic segment, and a hydrophobic β‐sheet forming peptide segment, poly(L‐valine) (PLVAL) was synthesized using a combination of Atom Transfer Radical Polymerization, Click Chemistry, and Nickel catalyzed ring opening of L‐valine N‐carboxyanhydride. This is the first reported use of Click Chemistry as an intermediary step for the ω‐amino functionalization of polymers to obtain macroinitiators that are free from deactivating or interfering molecules to be used in subsequent Ni‐catalyzed ring opening reaction. The efficiency of the end‐group functionalization in the macroinitiator is about 90%. Three different PAA‐b‐PLVAL hybrid copolymers with molecular weight range of 8000–15,000 and Mw/Mn <1.3 had been prepared by varying the monomer to macroinitiator ratio. In addition, the highest achievable molecular weight in the copolymerization was found to be limited by the solubility of the growing chains. This combined synthetic approach can potentially be extended for the synthesis of a multitude of other peptide hybrid systems, and hence will be of interest in the preparation of peptide hybrid systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2646–2656, 2007

Influences of MonoSilanolIsobutyl-POSS on thermal stability of polymethylsilxoane

Incorporation of polyhedral oligomeric silsesquioxane (POSS) molecules into polymer matrix resulted in increased used and decomposition temperatures. Polymethylsiloxane (PMS)/MonoSilanolIsobutyl-POSS hybrid copolymers containing various proportions of MonoSilanolIsobutyl-POSS were prepared. The structures and thermal properties of the obtained products were characterized with Gel Permeation Chromatography (GPC), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), differential thermogravimetric analysis (DTG) and X-ray photoelectron spectroscopy (XPS). The GPC and FTIR spectra suggested successful bonding of MonoSilanolIsobutyl-POSS and PMS. TGA, DTG and XPS analysis revealed that MonoSilanoIsobutyl-POSS reinforced PMS are thermally more stable than the original PMS, primarily by the elimination of SiOH effects, the nanoreinforcement effect of POSS, the retardation of polymer chain motion and the formation of SiO2 protective layer.

From Rings to Polymers

A short review of the origins and development of my research program at the University of Vermont in the area of inorganic polymers is presented. The topics include the discovery of a class of hybrid polymers and copolymers in which an inorganic ring such as a cyclophosphazene or cycloborazine system is a substituent on a carbon polymer chain. The subsequent elucidation of the electronic and chemical reactivity factors which control the formation of these materials allowed for design of successive generations of improved materials. Additional topic includes work in polyphosphazenes which have substituents with exploitable organic functionality.

Synthesis, characterization, and properties of poly(vinyl acetate)‐ and poly(vinyl alcohol)‐grafted chitosan

AbstractGraft copolymers of chitosan and vinyl acetate were synthesized by free radical technique using cerium (IV) as the initiator. Under controlled conditions, as much as 92% grafting with a grafting yield of 30–40% could be achieved. Chitosan‐g‐poly(vinyl alcohol) copolymers were derived by the alkaline hydrolysis of the chitosan‐g‐poly(vinyl acetate) precursor. Thermogravimetric, FTIR, and X‐ray diffraction analyses of chitosan and the copolymers confirmed the grafting reaction between chitosan and vinyl acetate and also the subsequent hydrolysis. Both the copolymers possessed very good film‐forming properties. Grafting resulted in a significant increase in mechanical strength of both the copolymers in the dry condition. Chitosan‐g‐poly(vinyl acetate) (CH‐PVAc) proved more hydrophobic than did pure chitosan, whereas chitosan‐g‐poly(vinyl alcohol) (CH‐PVOH) exhibited enhanced hydrophilicity as evident from their swelling characteristics and contact angle measurements. The enhanced swelling of CH‐PVOH was ascribed to the presence of the pendant poly(vinyl alcohol) group. At pH 1.98, the CH‐PVAc copolymer films showed greater stability than do pure chitosan films, which is highly beneficial for specific biomedical applications. Both the copolymers showed lower glass transition temperature than do pure chitosan. Grafting did not affect the overall thermal stability, and the differential thermogram substantiated the grafting. The investigations indicate that the synthetic–natural hybrid copolymers having desirable mechanical properties and tailored hydrophilic/hydrophobic characteristics are realizable. These polymers could be exploited for varied biomedical applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1852–1859, 2007

Electronic behavior of calcined material obtained from a gallium- N-phenylene- N hybrid copolymer

Calcination of a gallium- N-phenylene- N hybrid copolymer under an argon atmosphere gave nano-sized gallium nitride–carbon cluster composite material. ESR spectral examinations of the calcined materials reveals the possibility of an electron transfer in the process of gallium nitride → carbon clusters with an oxidation site at gallium nitride particles and a reduction site at carbon clusters. The calcined material was found to reduce methylene blue under visible light irradiation.

Electron transfer behavior of calcined material obtained from a samarium-O–phenylene-S–nickel-S–phenylene-O hybrid copolymer

Calcination of a samarium-O–phenylene-S–nickel-S–phenylene-O hybrid copolymer under an argon atmosphere gave Sm 2O 3–carbon cluster–Ni 3S 4 composite material. ESR spectral examinations of the calcined materials revealed the possibility of a two-step electron transfer in the process of Sm 2O 3 → carbon cluster → Ni 3S 4 with an oxidation site at Sm 2O 3 particles and a reduction site at Ni 3S 4 particles. The calcined material was found to reduce methylene blue under visible light irradiation.

Electronic behaviours of calcined materials from a (S-nickel-S-phenylene-O)-strontium-(O-phenylene-S-selenium-S) hybrid copolymer

The calcination of a (S-nickel-S-phenylene-O)-strontium-(O-phenylene-S-selenium-S) hybrid copolymer under an argon atmosphere at 400–600 ∘C was performed. 600 ∘C-calcined material was found to be composed of nano-sized NiS, SrS and Se particles in the matrix of the carbon clusters. ESR spectral examinations of the calcined material suggest the possibility of an electron transport in the process of carbon clusters → NiS → SrS → Se with a photoresponsive oxidation–reduction function.

Polypeptide and Polypeptide Hybrid Copolymer Synthesis via NCA Polymerization

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

(ニオビウム-O-フェニレン-S) - (カドミウム-S-フェニレン-O) 共重合体からなる焼成体の電子的挙動

The calcination of a (niobium-O-phenylene-S)- (cadmium-S- phenylene-O) hybrid copolymer under an argon atmosphere gave nano-sized Nb 2 O 5 / carbon clusters / CdS hybrid material. ESR spectral examinations suggest the possibility of an electron transfer in the process of Nb 2 O 5 → carbon clusters → CdS → carbon clusters.

Electronic Behavior of Calcined Material Obtained from a Tantalum-O-Phenylene-O Hybrid Copolymer

Calcinations of a tantalum-O–phenylene-O hybrid copolymer under an argon atmosphere have been found to give nano-sized tantalum oxide-carbon clusters composite material. ESR spectral examinations of the composite material suggest that the electron transfer from the tantalum oxide particles to the carbon clusters took place to raise a visible-light responsive function with an oxidation site in the tantalum oxide particle and a reduction site in the carbon cluster.

Upgrading of the fracture properties of multi-layered PMMA-nanosilica materials by interface modification

Hybrid copolymers of methyl methacrylate and methacryloyl grafted nanosilica (MMA-MGS) exhibit a higher modulus, but also a marked embrittlement, as compared to pure poly(methyl methacrylate) (PMMA). With the aim of overcoming this latter feature detrimental for industrial applications, multilayered materials based on these hybrids were prepared by inserting pure polymer layers between the nanohybrid layers. Insertion of thin and 'soft' layers of poly(ethyl acrylate) (PEA) between the nanohybrid layers leads to a marked toughening resulting from crack smoothing at each interface. However, this procedure is detrimental to the Young's modulus, except for extremely thin (ca. 1 μm) PEA layers. Alternatively, insertion of 100 μm thick 'hard' layers of PMMA also produces toughening, as the consequence of crack deviation at the layer interface. The latter procedure presents potential interest for applications because the Young's modulus of the assembly remains very close to that of the monolithic hybrid. The observed behavior of these assemblages is analyzed within the framework of fracture mechanics.

Hybrid Dendritic‐Linear Copolymers: Synthesis and Reactivity

AbstractA novel hybrid aromatic dendritic‐linear copolymer from Jeffamine® was synthesized by an adaptation of Kakimoto's procedure. Comparative studies of reactivity between aromatic and aliphatic hybrid dendritic‐linear copolymers were carried out, through which the best reactivity and the derivatizing capacity of this novel copolymer were clearly demonstrated for the aromatic hybrid dendritic‐linear copolymer. Schiff's base formation by reaction with a chromophore (MFVF) gave hybrid copolymer interesting crosslinkable properties.

Viscoelastic properties of hybrid copolymers based on methacryloxypropyl-grafted nanosilica and methyl methacrylate

The linear viscoelastic behavior of “model” hybrid materials based on methyl methacrylate and methacryloxypropyl-grafted nanosilica was investigated. As unique features, the materials under study present an excellent dispersion of silica within the polymer matrix and are almost free of uncross-linked chains. In addition, very progressive changes in network architecture are available, resulting from changes in particle diameter, d, volume fraction of filler, Φ, number of methacryloyl units grafted per surface unit of silica particle, n, and nature of the grafting agent. The influence of these parameters on the characteristics of the mechanically active relaxations α and β was examined. Emphasis was put on the storage modulus, E′, on the loss modulus, E′′, and on their dependence on filler volume fraction. E′′ values were shown to simply account for the reduction of the mechanical energy lost within the material, in connection to the occurrence of polymer molecular motions. Analysis of E′ variations as a function of Φ was based on the theoretical models available in the literature to account for the contribution of the spherical filler particles. In the glassy state, Kerner’s and Christensen and Lo’s models yielded comparable results. In the rubbery state, Guth and Gold’s model was shown to prevail on Kerner’s model.

Electronic properties of ruthenium sulfide–carbon cluster composite material obtained by calcination of an alternating ruthenium–S–phenylene hybrid copolymer

Calcination of an alternating ruthenium–S–phenylene hybrid copolymer under an argon atmosphere was found to give nano-sized ruthenium sulfide/carbon cluster composite material. ESR spectral examinations of the material revealed that an electron transfer from ruthenium sulfide particles to carbon clusters took place to raise a visible-light responsive oxidation–reduction function with an oxidation site at ruthenium sulfide particles and a reduction site at carbon clusters. The surface of the calcined material was modified with Pt particles, and the reduction ability of the resulting modified material was examined.

Electronic behavior of calcined material obtained from a tantalum- O-phenylene- S-tin- S-phenylene- O hybrid copolymer

Calcination of a tantalum- O-phenylene- S-tin- S-phenylene- O hybrid copolymer under an argon atmosphere gave SnS–carbon clusters–Ta 2O 5 composite material. Electron spin resonance (ESR) and X-ray photospectrometry (XPS) spectral examinations suggest the possibility of an electron transfer in the process of SnS → carbon clusters → Ta 2O 5 with an oxidation site at SnS particles and a reduction site at Ta 2O 5 particles. The calcined material could decompose methylene blue under visible light irradiation.