Hybrid Copolymers Research Articles

Preparation of Hybrid Nanocapsules

AbstractHybrid nanoparticles with a polystyrene core and a hybrid copolymer shell were used to produce hybrid nanocapsules by dissolving the polystyrene core from the previously elaborated core‐shell particles. Following previous works, the core‐shell particles were prepared by emulsion polymerization of styrene and subsequent addition of γ‐methacryloxy propyl trimethoxy silane (MPS) to produce the shell by copolymerization reaction of MPS with the residual styrene. Core extraction was performed by diluting the core‐shell particles in an excess of tetrahydrofuran (THF). Two procedures were investigated to separate the dissolved polymer chains from the nanocapsules. In the first procedure, the polymer was isolated by successive centrifugation and redispersion in THF, whereas in the second procedure, the free polymer chains were removed by dialysis. The polymer molecular weight was optimized in order to promote dissolution of the polymer chains and allow them to diffuse through the shell.

Synthesis of polypeptide/inorganic hybrid block copolymers

Polypeptide/inorganic hybrid copolymers were obtained by a four-step synthetic approach combining (i) atom transfer polymerization of tert-butyl acrylate, (ii) chemical modification of the bromo end groups of ATRP-polymers into primary amino group using Gabriel reaction, (iii) ring opening polymerization of N ε-trifluoroacetyl- l-lysine or γ-benzyl- l-glutamate N-carboxyanhydrides followed by (iv) the transamidification reaction using a large excess of (3-aminopropyl)trimethoxysilane to substitute the tert-butyl groups of the poly( tert-butyl acrylate) block. Products were characterized using 1H NMR, FT-IR, DSC and MALDI-TOF MS. These techniques proved that polymerization of tert-butyl acrylate was controlled whatever the molecular weight targeted and that bromide was quantitatively converted to amino end group by a original method leading to the synthesis of copolymers in the presence of N-carboxyanhydrides as monomers. Amphiphilic polypeptide/inorganic hybrid copolymers were then achieved.

Surface studies of corona treated polydimethylsiloxane‐block‐polystyrene hybrid copolymer films

AbstractLinear hybrid block copolymers of polydimethylsiloxane (PDMS) and polystyrene (PS) were synthesized using living sequential anionic polymerization. Sample films of these block copolymers were thermally annealed for 48 hr at 120°C to promote phase segregation and allow for the preferential surface segregation of PDMS. The films were then exposed to corona discharge for 30 min. Optical microscopy and scanning electron microscopy (SEM) were used to identify surface cracks due to the formation of a silica‐like glassy layer after corona exposure. Slow positron beam studies were used to evaluate the degradation phenomenon and provide the first evidence of silica‐like degradation layers forming on the surface of PDMS containing hybrid polymer films, after corona exposure. It also allowed determination of the thickness of the glassy layer. Contact angle measurements also showed the first evidence that the same hydrophobic loss and recovery phenomenon for the corona treated hybrid polymer films occurs, as with pure PDMS samples. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Molecular chimeras: New strategies in the design of functional materials

Natural and synthetic polymers have a number of common traits; however, each class of compounds demonstrates specific properties. The design of hybrid copolymers based on such different macromolecules is a unique strategy for constructing smart materials. The review deals with two aspects: state-of-the-art studies in bioinspired hybrid systems, including those based on oligopeptides and oligothiophenes, and achievements in the computer modeling of this new class of molecular chimeras.

Calorimetric study of organic-inorganic copolymers of ethylene glycol methacrylate and titanium dioxide

Hybrid copolymers of ethylene glycol monomethacrylate and titanium dioxide with different ratios between the organic and inorganic components were studied using differential scanning calorimetry and thermogravimetric analysis. It was shown that the introduction of the inorganic component enhances the thermal stability of composites compared to that of poly(ethylene glycol monomethacrylate). It was found that the onset temperature of the thermal degradation of copolymers increases with an increase in the titanium dioxide content.

ChemInform Abstract: Immobilization of Ruthenium in Organic—Inorganic Hybrid Copolymers: A Reusable Heterogeneous Catalyst for Oxidation of Alcohols with Molecular Oxygen.

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 of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Electronic behavior of calcined material obtained by microwave treatment of a tin- O-phenylene- O hybrid copolymer

Microwave treatment of a mixture of a tin- O-phenylene- O hybrid copolymer and graphite gave SnO 2–carbon cluster–Sn composite material. The resulting composite materials were characterized by using XRD, SEM, EDX and TEM. ESR spectral examinations of the calcined materials reveal the possibility of a photo-responsive electron transfer in the process of carbon clusters → SnO 2 and/or Sn. The calcined material was found to decompose 7,7,8,8-tetracyanoquinodimethane under light irradiation.

Electronic behavior of carbon clusters/hafnium oxide composite material

Abstract An alternating hafnium-O-phenylene hybrid copolymer was calcined under the reduced pressure at 400–700 °C to obtain black-colored materials. XRD and TEM analyses showed that the calcined materials were composed of carbon clusters with the diameters of 20 nm and hafnium oxide particles with the diameters of a few nm. ESR spectral examinations revealed that the calcined materials formed a stable cation radical on the carbon clusters and exhibited an oxidation–reduction function. When Au particles were supported on the material, an efficient oxidation–reduction function was found to appear.

Immobilization of Ruthenium in Organic–Inorganic Hybrid Copolymers: A Reusable Heterogeneous Catalyst for Oxidation of Alcohols with Molecular Oxygen

A novel organic-inorganic hybrid ruthenium (HB Ru) catalyst for the oxidation of alcohols with molecular oxygen has been developed. The catalyst was prepared from a polystyrene-based copolymer, which includes a trimethoxysilyl functionality, and dichlorotris(triphenylphosphine)ruthenium, [RuCl2(PPh3)3], as the metal source. A sol-gel process was employed for heterogenization of the catalyst. The choice of both ruthenium species and trialkoxysilyl-bearing monomers was found to be important for high catalytic activity. In the presence of HB Ru corresponding to 5 mol % loading of ruthenium, the alcohols were oxidized with molecular oxygen or air at atmospheric pressure without any additives to afford the corresponding aldehydes or ketones in good to excellent yields. The catalyst could be recovered and reused at least five times without loss of activity.

Surface-Attached PDMAA−GRGDSP Hybrid Polymer Monolayers that Promote the Adhesion of Living Cells

Peptide-polymer hybrid molecules are being introduced, where one part of the molecule (i.e., the peptide) promotes the adhesion of living cells, whereas the other part of the molecule (i.e., the synthetic polymer) is known to prevent cell adhesion. The hybrid copolymer, poly(dimethylacrylamide) (PDMAA)-glycine-arginine-glycine-aspartic acid-serine-proline (GRGDSP) was synthesized by first preparing an initiator-modified peptide and in a second step growing the PDMAA block directly off the peptide through atom transfer radical polymerization (ATRP). The PDMAA block length can be varied by adjusting appropriate polymerization conditions, thereby changing progressively the amount of the cell-repelling part of the molecule. The hybrid copolymer was further used to prepare surface-attached peptide-polymer monolayers at planar solid glass substrates through a photochemical immobilization process. By blending of the hybrid copolymer with PDMAA homopolymer (i.e., without peptide), the apparent peptide film concentration can be varied in a very simple manner. The adhesion of human skin fibroblast cells in serum-free medium was investigated as a function of the amount of peptide-polymer in the solution used for film preparation. Cells do not adhere to a pure PDMAA monolayer; however, already 0.02 wt % of peptide in the film is enough to induce cell adhesion, and 0.1 wt % promotes stress-fiber formation within adherent cells. Using lithographical means, chemically micropatterned peptide-polymer films were prepared that allow for a spatial control of the adhesion of living cells and thus they constitute a simple platform for the design of live-cell biochips.

Synthesis of a Net-Worked Strontium-O-Phenylene-S-Tellurium Hybrid Co-polymer Having a Two-Step Electron Transfer Nature

A strontium-O-phenylene-S-tellurium hybrid co-polymer was prepared by initially reacting 4-hydroxythiophenol with tellurium ethoxide, followed by a subsequent reaction with strontium isopropoxide, and the electronic behavior of the co-polymer was examined. From the results of ESR spectral examinations and ab initio calculations regarding the co-polymer models, the co-polymer was deduced to have a function of two-step electron transfer from the phenylene group to the strontium atom via the tellurium atom.

Novel approaches for the preparation of silica-based zwitterionic hybrid copolymers

Two novel routes for the preparation of silica-based zwitterionic hybrid copolymers were proposed. A series of zwitterionic hybrid copolymers were prepared by the sulfonation of phenyl groups and the quaternary amination of tertiary amine groups alternately. Both FT-IR and 1H NMR spectra confirm the step products. TGA and DrTGA analyses indicate that the thermal stability of these zwitterionic hybrid copolymers is higher than 400°C. The determination of sulfonation degree reveals that the zwitterionic hybrid copolymer (c) from sulfonation–quarteramination (Route I) has the minimal value; meanwhile the anion-exchange capacity exhibits that the zwitterionic hybrid copolymer (e) from quarteramination–sulfonation (Route II) has the minimal value. These findings demonstrate the impact of electrostatic effect on the charge content of ionic groups. MALDI-TOF mass spectra exhibit that the decrease in the stability of the charged hybrid copolymers can be ascribed to the electrostatic effect between the molecular chains. The surface SEM images demonstrate that the surface of zwitterionic hybrid copolymer (e) from quarteramination–sulfonation (Route II) has some aggregated particles and form clusters regions in the hybrid matrix, which can also be attributed to the ionic interactions between those charged groups.

The electronic behavior of calcined material obtained from a manganese-O-phenylene-S-rhenium-S-phenylene hybrid copolymer

Abstract The calcinations of a manganese- O -phenylene- S -rhenium- S -phenylene hybrid copolymer under an argon atmosphere at 600–900 °C were carried out. Calcined materials were found to be composed of MnS particles and metallic Re in a matrix of carbon clusters. ESR spectra reveal the calcined materials to have a photoresponsive oxidation–reduction function via the electron transfer process MnS → Re and/or carbon clusters. The surface of the calcined materials was modified with Pt particles and the reduction ability of the resulting materials was examined. It has been found that the material calcined at 800 °C loaded with Pt particles could decompose water under visible-light irradiation.

Self-Assembly of Methacrylic Nanostructured Copolymers Containing Polyhedral Oligomeric Silsesquioxanes

AbstractTwo hybrid copolymer series obtained by free-radical copolymerization of methacrylcyclohexyl Polyhedral oligomeric silsesquioxane (POSS) with butyl methacrylate or 2-ethylhexylmethacrylate were characterized by 1H-NMR spectroscopy, gel permeation chromatography (GPC), X-rays Diffraction (XRD), differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Reactivity ratios were calculated by low yield composition data suggesting the formation of random copolymers with low probability of poly-POSS sequences. XRD studies showed the crystallization behaviour of the inorganic phase independently on the POSS content; however sample processing by solvent casting effectively hindered the copolymer self-assembling ability. DSC suggests the formation of polyphasic structures with Tg increasing with POSS content, and with endothermal peaks occurring at higher temperature. Finally TGA shows an improved thermal stability of hybrid copolymers with char yield correlated to the level of inorganic phase.

Preparation of Magnetic Hybrid Copolymer–Cobalt Hierarchical Hollow Spheres by Localized Ostwald Ripening

We report a one-step solvothermal method to prepare magnetic hybrid copolymer–Co hierarchical hollow spheres by localized Ostwald ripening. The initial stage is the aggregation of primary inorganic nanoparticles whose surfaces are partially adsorbed by copolymer PEG–PPG–PEG to form solid spheres followed by hollowing of the core and the progressive matter redistribution from the interior to the exterior. Meanwhile, amorphous inorganic particles grow to cubic crystallites. Finally, a hollow spherical architecture with an extensively roughened surface is obtained by this self-transformation. The effect of NaOH concentration (served as a catalyst and reagent) on the sphere morphology is also checked by time-dependent experiments. When decreasing the mass of NaOH from 7.5 to 2.5 mmol, a morphology transformation from porous hollow spheres to double-wall spheres and then to single-wall spheres with platelet-like building units aligned disorderly on the outer surfaces is observed, and this morphology transformation is related to Ostwald ripening. Our results suggest that these nanoparticle-based hollow hierarchical spheres collected by the self-transformation of precursor objects could be of potential applicability in the fields of material science and biomedical technology.

The effect of cannula material on the incidence of peripheral venous thrombophlebitis

The incidence of thrombophlebitis following the use of two types of cannulae, a new generation polyurethane cannula Biovalve PUR and a polyurethane hybrid co-polymer Vialon cannula, was compared in a randomised trial. Seventy patients scheduled for elective cardiac surgery were randomly assigned to have either a Biovalve cannula or a Vialon cannula inserted before induction of anaesthesia. Postoperatively, the cannulae were removed either as soon as signs of thrombophlebitis were observed or at the end of seven days, whichever was earlier. There was a significantly lower incidence of thrombophlebitis in the Biovalve PUR group (17%) compared to the Vialon group (60%) at the end of seven days (p < 0.001). None of the cannulae tip cultures resulted in the growth of micro-organisms. There was also a lower incidence of the need for re-siting with the Biovalve than with the Vialon cannulae.

Formation of inorganic protonic-acid polymer via inorganic–organic hybridization: Synthesis and characterization of polymerizable olefinic organosilyl derivatives of mono-lacunary Dawson polyoxometalate

A novel polymerizable organosilyl-modified Dawson-type polyoxometalate (POM) [α 2-P 2W 17O 61{CH 2 C(CH 3)COO(CH 2) 3Si} 2O] 6− ( 1) was synthesized as both Me 2 NH 2 + salt ( Me 2 NH 2- 1) and H + form ( H- 1). They were characterized with complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR, ( 1H, 13C, 29Si, 31P and 183W) NMR and n-butylamine titration method. H- 1 was immobilized to a polymer network through free radical copolymerization with methyl methacrylate ( MMA). The acidities of H- 1 and hybrid copolymer ( H-1-co- MMA) were evaluated using the Hammett indicators (dicinnamalacetone and benzalacetophenone; p K a values of the protonated indicators are −3.0 and −5.6, respectively). The p K a value of H- 1 was estimated as that between −3.0 and −5.6 in CH 3CN solution and H- 1 was immobilized in H-1-co- MMA with the original acidity being retained. Glass transition point ( T g) and molecular weight distribution of H- 1-co- MMA were affected by the used amount of H- 1 because of the cross-linking effect of H- 1.

Novel fire resistant matrixes for composites from cyclic poly(butylene terephthalate) oligomers

AbstractThe objective of the work is to exploit the processing advantages of c‐PBT oligomers, essentially required in industrial practice to produce new, robust, multifunctional hybrid copolymers of c‐PBT oligomers in a single reaction‐molding step, which will be suitable for the use in continuous fiber composites with excellent flame retardant properties. In this article a series of copolyesters were synthesized by using in situ polymerization of cyclic poly(butylene terepthalate) oligomers (c‐PBT) and hydroxyl terminated bisphenols and hydroxylated siloxanes in the presence of a tin catalyst at a moderate temperature. The in situ copolymerization was conducted with various c‐PBT/tetrabromobisphenol A (TBBPA), bisphenol A diglycidyl ether (BPADGE) and Carbinol PDMS feed ratios respectively. The copolyesters were characterized by GPC, NMR, and DSC techniques. Pyrolysis‐combustion flow calorimeter (PCFC) and pyrolysis gas chromatography/mass spectrometry (PyGC/MS) studies were performed to characterize the fire retardant properties of the copolymers during combustion. POLYM. ENG. SCI., 47:1536–1543, 2007. © 2007 Society of Plastics Engineers

Preparation, Photophysics, and Electrochemistry of Segmented Comonomers Consisting of Thiophene and Pyrimidine Units: New Monomers for Hybrid Copolymers

An efficient coupling route to novel pi-conjugated comonomers consisting of pyrimidine, thiophene, and bithiophene units was developed. The novel pi-donor-acceptor-donor and pi-donor-acceptor-acceptor-donor conjugated compounds were prepared by Suzuki heterocoupling and Ni(0)-mediated Ullman homocoupling reactions. Photophysical investigation of these alternating pi-donor and acceptor compounds indicated that the deactivation of their singlet excited state proceeds predominately by fluorescence and results in high fluorescence quantum yields. Intersystem crossing to the triplet state was also present in ca. 10%. Quantification of the triplet manifold by laser flash photolysis further revealed that bithiophene produced its triplet state in only 31%. Cyclic voltammetry studies showed that the comonomers undergo both oxidation and reduction leading to their radical cations and radical anions, respectively. The radical cations are highly reactive and undergo anodic polymerization resulting in mutual p- and n-type dopable polymers. The extended conjugation resulting from polymer formation was confirmed by both absorbance and fluorescence spectroscopy and by GPC. Ruthenium binding with the conjugated homocoupled ligand was also found resulting in a hybrid alternating copolymer with significantly different spectroscopic and electrochemical properties relative to its metal-free counterpart.

Electronic behaviors of calcined materials obtained from samarium-O-aryl moiety hybrid copolymers

Hybrid copolymers with samarium-O-aryl moiety frameworks were successfully prepared by reacting samarium(III) chloride with diols in the presence of proton sponge. The compositions of the resulting copolymers were determined using IR spectroscopy and inductively coupled plasma atomic emission spectrometry (ICP-AES). The calcinations of samarium-O-aryl moiety hybrid copolymers under a reduced pressure gave nano-sized samarium oxide/carbon clusters composite materials. The structural characterizations of the calcined materials were carried out by X-ray diffraction (XRD) spectra and transmission electron microscopy (TEM). ESR spectral examinations of the calcined materials indicate that an electron transfer takes place from the samarium oxide particles to carbon clusters.