Ionic liquid as plasticizer for europium(III)-doped luminescent poly(methyl methacrylate) films

Flexible luminescent polymer films were obtained by doping europium(III) complexes in blends of poly(methyl methacrylate) (PMMA) and the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(6)mim][Tf2N]. Different europium(III) complexes have been incorporated in the polymer/ionic liquid matrix: [C(6)mim][Eu(nta)(4)], [C(6)mim][Eu(tta)(4)], [Eu(tta)(3)(phen)] and [choline](3)[Eu(dpa)(3)], where nta is 2-naphthoyltrifluoroacetonate, tta is 2-thenoyltrifluoroacetonate, phen is 1,10-phenanthroline, dpa is 2,6-pyridinedicarboxylate ( dipicolinate) and choline is the 2-hydroxyethyltrimethyl ammonium cation. Bright red photoluminescence was observed for all the films upon irradiation with ultraviolet radiation. The luminescent films have been investigated by high-resolution steady-state luminescence spectroscopy and by time-resolved measurements. The polymer films doped with beta-diketonate complexes are characterized by a very intense D-5(0) -> F-7(2) transition ( up to 15 times more intense than the D-5(0) -> F-7(1)) transition, whereas a marked feature of the PMMA films doped with [choline](3)[Eu(dpa)(3)] is the long lifetime of the D-5(0) excited state (1.8 ms).

High performance polyester-based materials

Biaxially oriented films produced from semi-crystalline, semi-aromatic polyesters are utilised extensively as components within various applications, including the specialist packaging, flexible electronic and photovoltaic markets. However, the thermal performance of such polyesters, specifically poly(ethylene terephthalate) (PET) and poly(ethylene-2,6-naphthalate) (PEN), is inadequate for several applications that require greater dimensional stability at higher operating temperatures. The work described in this project is therefore primarily focussed upon the copolymerisation of rigid comonomers with PET and PEN, in order to produce novel polyester-based materials that exhibit superior thermomechanical performance, with retention of crystallinity, to achieve biaxial orientation. Rigid biphenyldiimide comonomers were readily incorporated into PEN and poly(butylene-2,6-naphthalate) (PBN) via a melt-polycondensation route. For each copoly(ester-imide) series, retention of semi-crystalline behaviour is observed throughout entire copolymer composition ratios. This phenomenon may be rationalised by cocrystallisation between isomorphic biphenyldiimide and naphthalenedicarboxylate residues, which enables statistically random copolymers to melt-crystallise despite high proportions of imide sub-units being present. In terms of thermal performance, the glass transition temperature, Tg, linearly increases with imide comonomer content for both series. This facilitated the production of several high performance PEN-based biaxially oriented films, which displayed analogous drawing, barrier and optical properties to PEN. Selected PBN copoly(ester-imide)s also possess the ability to either melt-crystallise, or form a mesophase from the isotropic state depending on the applied cooling rate. An equivalent synthetic approach based upon isomorphic comonomer crystallisation was subsequently applied to PET by copolymerisation with rigid diimide and Kevlar®-type amide comonomers, to afford several novel high performance PET-based copoly(ester-imide)s and copoly(ester-amide)s that all exhibited increased Tgs. Retention of crystallinity was achieved in these copolymers by either melt-crystallisation or thermal annealing. The initial production of a semi-crystalline, PET-based biaxially oriented film with a Tg in excess of 100 °C was successful, and this material has obvious scope for further industrial scale-up and process development.

High conductivity molten salts based on the imide ion

The bis(trifluoromethanesulfonyl)imide ion has recently been used in its lithium salt as a useful ion in solid polymer electrolytes because of the reduced degree of ion interaction its diffuse charge generates. In this work we have synthesised a number of novel salts based on the ammonium and pyrrolidinium cations of this anion. The salts all show reduced melting points compared with analogous halide salts. In some cases they are molten at room temperature. This latter group of salts have been characterized with respect to their properties as ionic liquids; the highest room temperature conductivity 2 mS cm⁻¹ being exhibited by methyl butyl pyrrolidinium imide. Many of the salts are glass forming, exhibiting glass transition temperatures in the region of −90°C.

Simultaneous polymerization and crosslinking for the synthesis of molecular-level graphene oxide-polyacryl amide-CeOx composites

Synthesis of molecular-level multiple-component composites are particularly challenging due to the lack of direct bonding among different components. In this study, molecular-level graphene oxide (GO)-polyacryl amide (PAM)-CeOx composites were successfully synthesized, using the simultaneous polymerization and crosslinking strategy. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) techniques confirmed that polyacryl amide (PAM) chains were successfully grafted onto the surface of GO. X-ray photoelectron spectroscopic (XPS) and X-ray diffraction (XRD) analyses further revealed the characteristic signals of cerium elements and CeO2 phase respectively. Scanning electron microscopy (SEM) showed that the surface morphology of the GO-PAM-CeOx composites was substantially thicker and rougher than those of the original GO. Further exploration of the reaction mechanism clearly demonstrate the existence of strong chelating interaction among PAM chains and Ce(IV) ions. In particular, the polymerization of acryl amide monomers and the crosslinking reaction between PAM and Ce(IV) or Ce(III) ions were realized simultaneously, leading to the final formation of molecular-level GO-PAM-CeOx composites. Moreover, the as-synthesized GO-PAM-CeOx composites were capable of effectively decomposing Rhodamine B under simulated sunlight, making it a potential candidate as a new photo catalyst. To sum up, this report demonstrates the potential utility of simultaneous polymerization and crosslinking method for the synthesis of other multiple-component composites at molecular-level.

Encapsulation of Local Anesthetic Bupivacaine in Biodegradable Poly(DL-lactide-co-glycolide) Nanospheres: Factorial Design, Characterization and Cytotoxicity Studies

Local anesthetic agents cause temporary blockade of nerve impulses productiong insensitivity to painful stimuli in the area supplied by that nerve. Bupivacaine (BVC) is an amide-type local anesthetic widely used in surgery and obstetrics for sustained peripheral and central nerve blockade. in this study, we prepared and characterized nanosphere formulations containing BVC. To achieve these goals, BVC loaded poly(DL-lactide-co-glycolide) (PLGA) nanospheres (NS) were prepared by nanopreciptation and characterized with regard to size distribution, drug loading and cytotoxicity assays. The 2(3-1) factorial experimental design was used to study the influence of three different independent variables on nanoparticle drug loading. BVC was assayed by HPLC, the particle size and zeta potential were determined by dynamic light scattering. BVC was determined using a combined ultrafiltration-centrifugation technique. The results of optimized formulations showed a narrow size distribution with a polydispersivity of 0.05%, an average diameter of 236.7 +/- 2.6 nm and the zeta potential -2.93 +/- 1,10 mV. In toxicity studies with fibroblast 3T3 cells, BVC loaded-PLGA-NS increased cell viability, in comparison with the effect produced by free BVC. In this way, BVC-loaded PLGA-NS decreased BVC toxicity. The development of BVC formulations in carriers such as nanospheres could offer the possibility of controlling drug delivery in biological systems, prolonging the anesthetic effect and reducing toxicity.

Electrochemical reduction and determination of Cibacron Blue F3GA at poly-L-lysine modified glassy carbon electrode

The oxidation of a reactive dye, Cibacron Blue F3GA, CB, (C.I. 61211), widely used in the textile industries to color natural fibers, was studied by electrochemical techniques. The oxidation on glassy carbon electrode occurs in two steps at 2.0 < pH < 10 involving one electron transfer each to the amine group leading to the imide derivative. Stable films of poly-L-lysine (PLL) in the presence of glutaraldehyde (GA) 97.5%:2.5% on glassy carbon electrode can be used to detect low levels of dye using its oxidation peak at +0.75V by voltammetry. Linear calibration graphs were obtained for the CB reactive dye, from 1.0 X 10(-6) to 1.0 X 10(-5) mol L-1 in B-R buffer, pH 2.0, using a pre-concentration off-line during 10 min. The detection limit (3 sigma/slope) was calculated to be 4.5 X 10(-8) mol L-1. Films of PLL can readily be applied for the determination of CB dye bearing aminoanthraquinone as chromophore and chlorotriazinyl as reactive group at concentrations at least 100 times lesser than using a glassy carbon electrode without modification. The method described was applied for the determination of CB dye in tap water and raw water collected from the municipal treatment plant with a recovery of 89.2% +/- 5.4 and 88.0% +/- 6.5, respectively. (c) 2005 Elsevier Ltd. All rights reserved.

Synthese und Charakterisierung zylindrischer Poly(2-oxazolin)bürsten als Nanocarrier für Drug Delivery Systeme

Inspiriert durch natürlich vorkommende Peptide, sind Poly(2-oxazoline) vielversprechende Kandidaten für Anwendungen in Bereichen des kontrollierten Wirkstoff- bzw. Gentransportes, wie die moderne Biomedizin dies fordert. Da Polyoxazoline als strukturisomere Amide von natürlichen Polypeptiden aufgefasst werden können, zeigen diese synthetischen Polymere in direktem Vergleich erhebliche Vorteile etwa hinsichtlich Zytotoxizät und Effizienz, was wesentlich dazu beitragen kann, aktuelle Hürden biomedizinischer Fragestellungen hinsichtlich Transport und Targeting zu überwinden. Darüber hinaus sollten zylindrische Polymerbürsten aufgrund ihrer molekularen, architekturbedingten Formanisotropie und jüngsten Ergebnissen insbesondere zur formabhängigen Endozytose sehr aussichtsreiche Kandidaten für den Einsatz zum Wirkstofftransport sein.rnrnDie vorliegende Arbeit widmete sich deshalb der Synthese und Charakterisierung von biokompatiblen zylindrischen Poly(2-oxazolin)bürsten als potentielle Nanotransporter von Wirkstoffen, Biomolekülen oder genetischem Material. Als Monomer wurde zunächst 2-Isopropyloxazolin gewählt, da das Polymer eine Phasenübergangstemperatur von 37 °C besitzt, was für Konjugatsynthesen wie auch diverse biomedizinische Applikationen interessant sein kann. Durch terminierende Methacrylamid Funktionalisierung der lebenden kationischen Oxazolinpolymerisation bzw. nachfolgende Endgruppen Transferreaktionen sind Makromonomere im Bereich 1000-5000 g/mol zugänglich. Erstmals gelang es so 2-Oxazolin basierte, hochmolekulare zylindrische Bürsten mit Konturlängen im Bereich von 250 nm mittels „Grafting Through“ Technik in freier radikalischer Polymerisation herzustellen.rnrnAusgehend von der entwickelten Syntheseroute konnten so neben Homo- und Blockcopolymerbürsten von 2-Ethyl-2-oxazolin und 2-Isopropyl-2-oxazolin auch Bürstenmoleküle aus statistischen Copolymeren von 2-Ethyl-2-oxazolin und unsubstituiertem 2-Oxazolin hergestellt werden. Während letztere die Einführung kationischer Gruppen durch selektivere Abspaltmethoden der Formylreste erlauben und so etwa DNA/RNA Komplexierungen ermöglichen können, bietet andererseits der in dieser Arbeit erstmalig demonstrierte Einsatz Azid-funktionalisierter Initiatoren zur kationischen Oxazolinpolymerisation unter Beibehaltung aller anderen sonstigen Reaktionsschritte auch die Möglichkeit der Synthese Azid-Endgruppen-funktionalisierter Makromonomere. Die „Grafting Through“ Methodik der freien radikalischen Makromonomer Polymerisation ist selbst bei diesen funktionalisierten Systemen von großem Vorteil, erlaubt sie auch hier den Zugang zu hochmolekularen Substraten mit einem Pfropfungs- bzw. Funktionalisierungsgrad von 100 %, da jede Seitenkette dieser zylindrischen Bürsten die aussenliegende, und damit sterisch leichter zugängliche funktionale Gruppe trägt. Dabei gelang es die Syntheseroute so zu gestalten, dass es möglich war alle vorgestellten Polymerbürsten mittels statischer und dynamischer Lichtstreuung hinsichtlich absoluter Molmasse und molekularer Dimension zu charakterisieren.rnIn weitereren Reaktionen konnten dann reaktive Fluoreszenzfarbstoffe mit Hilfe kupferfreier 1,3 dipolarerer Addition (kupferfreie „Click-Chemie“) an die Azid-funktionalisierten Polymerbürsten angebunden werden, so dass eine wesentliche Voraussetzung für die Detektion in in vivo und in vitro Experimenten erfüllt werden kann. Darüber hinaus gelingt die quantitative polymeranaloge Umsetzung der Azid- zu Aminogruppen durch eine polymeranalog geführte Reduktion nach Staudinger; damit können an diesen Systemen auch etablierte Konjugationstechniken an Aminogruppen durchgeführt werden. Zudem erlauben die Aminogruppen-haltigen Polymerbürsten durch Protonierung schon bei physiologischem pH die Komplexierung von DNA oder RNA. rnrnErste Lichtstreumessungen in Blutserum zeigen im Falle der kationischen Aminogruppen tragenden Polymerbürsten zwar Aggregation, was aber durch entsprechende Umsetzung nach Konjugation wahrscheinlich unterdrückt werden kann, zeigen doch die entsprechenden Precursorpolymerbürsten mit Azidgruppen in Serum keinerlei Aggregation.rnrnZellaufnahmestudien in dendritische Zellen zeigen nur im Falle einer Azid-funktionalisierten Poly(2-isopropyl-2-oxazolin)bürste eine unspezifische Aufnahme. Die hydrophileren Poly(2-oxazolin)bürsten weise keine unspezifische Aufnahme auf, was eine wichtige Anfoderung für die Verwendung als Polymercarrier in der Krebsimmuntherapie ist.rn

Miscibility and phase separation in blends of phenolphthalein poly(aryl ether ketone) and poly(ethylene oxide): a differential scanning calorimetric study

Miscibility and phase separation in the blends of phenolphthalein poly(aryl ether ketone) (PPAEK) and poly(ethylene oxide) (PEO) were investigated by means of differential scanning calorimetry (DSC). The PPAEK/PEO blends prepared by solution casting from N,N-dimethylformamide (DMF) displayed single composition-dependent glass transition temperatures (T-g), intermediate between those of the pure components, suggesting that the blend system is miscible in the amorphous state at all compositions. All the blends underwent phase separation at higher temperatures and the system exhibited a lower critical solution temperature (LCST) behavior. A step-heating thermal analysis was designed to determine the phase boundaries with DSC. The significant changes in the thermal properties of blends were utilized to judge the mixing status for the blends and the phase diagram was thus established. (C) 2004 Elsevier B.V. All rights reserved.

Encapsulation of Local Anesthetic Bupivacaine in Biodegradable Poly(DL-lactide-co-glycolide) Nanospheres: Factorial Design, Characterization and Cytotoxicity Studies

Local anesthetic agents cause temporary blockade of nerve impulses productiong insensitivity to painful stimuli in the area supplied by that nerve. Bupivacaine (BVC) is an amide-type local anesthetic widely used in surgery and obstetrics for sustained peripheral and central nerve blockade. in this study, we prepared and characterized nanosphere formulations containing BVC. To achieve these goals, BVC loaded poly(DL-lactide-co-glycolide) (PLGA) nanospheres (NS) were prepared by nanopreciptation and characterized with regard to size distribution, drug loading and cytotoxicity assays. The 2(3-1) factorial experimental design was used to study the influence of three different independent variables on nanoparticle drug loading. BVC was assayed by HPLC, the particle size and zeta potential were determined by dynamic light scattering. BVC was determined using a combined ultrafiltration-centrifugation technique. The results of optimized formulations showed a narrow size distribution with a polydispersivity of 0.05%, an average diameter of 236.7 +/- 2.6 nm and the zeta potential -2.93 +/- 1,10 mV. In toxicity studies with fibroblast 3T3 cells, BVC loaded-PLGA-NS increased cell viability, in comparison with the effect produced by free BVC. In this way, BVC-loaded PLGA-NS decreased BVC toxicity. The development of BVC formulations in carriers such as nanospheres could offer the possibility of controlling drug delivery in biological systems, prolonging the anesthetic effect and reducing toxicity.