Fluorinated Linkers Enable High-Voltage Pyrrolidinium-based Dicationic Ionic Liquid Electrolytes.

Novel fluorinated, pyrrolidinium-based dicationic ionic liquids (FDILs) as high-performance electrolytes in energy storage devices have been prepared, displaying unprecedented electrochemical stabilities (up to 7 V); thermal stability (up to 370 °C) and ion transport (up to 1.45 mS cm). FDILs were designed with a fluorinated ether linker and paired with TFSI/FSI counterions.

1-Ethyl-3-methylimidazolium Acetate as a Reactive Solvent for Elemental Sulfur and Poly(sulfur nitride).

We investigate the reactive dissolution process of poly(sulfur nitride) (SN) in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [EMIm][OAc] in comparison to the process of elemental sulfur in the same IL. It has been known from the literature that during the reaction of S with [EMIm][OAc], the respective thione is formed via a radical mechanism. Here, we present new results on the kinetics of the formation of the respective imidazole thione (EMImS) via the hexasulfur dianion [S] and the trisulfur radical anion [S].

Development of Poly(sorbitol adipate)--poly(ethylene glycol) Mono Methyl Ether-Based Hydrogel Matrices for Model Drug Release.

Hydrogels were prepared by Steglich esterification and by crosslinking pre-synthesized poly(sorbitol adipate)--poly(ethylene glycol) mono methyl ether (PSA--mPEG) using different-chain-length-based disuccinyl PEG. PSA and PSA--mPEG were investigated for polymer degradation as a function of time at different temperatures. PSA--mPEG hydrogels were then evaluated for their most crucial properties of swelling that rendered them suitable for many pharmaceutical and biomedical applications.

A Living Topochemical Ring-Opening Polymerization of Achiral Amino Acid N-Carboxy-Anhydrides in Single Crystals.

A living topochemical ring-opening polymerization (ROP) of achiral amino-acid N-carboxyanhydrides (NCAs) is reported. Single crystals of the NCAs of α-aminoisobutyric acid (Aib) and 1-aminocyclohexanecarboxylic acid (ACHC) were grown, allowing a ring-opening polymerization macroscopically induced by amines. The single crystals could be polymerized at temperatures from 25-50 °C after physically contacting the amine-based initiator with the crystals.

Formation of Surface Wrinkles in Collapsed Langmuir Films of a Polyhedral Oligomeric Silsesquioxane Containing Diblock Copolymer.

Surface pressure versus mean molecular area isotherms of Langmuir films of a hybrid diblock copolymer of poly(ethylene glycol) (PEG) and poly(methacrylo polyhedral oligomeric silsesquioxane) P(MA-POSS) together with Brewster angle microscopy reveal details of the phase transitions. The formation of a periodic wrinkling pattern in collapsed films is observed by epifluorescence microscopy after applying several compression-expansion cycles above the surface pressure of ≈18 mN/m. The wrinkle formation is reversible upon compression and expansion of the Langmuir films.

Crystallization of Poly(ethylene)s with Regular Phosphoester Defects Studied at the Air-Water Interface.

Poly(ethylene) (PE) is a commonly used semi-crystalline polymer which, due to the lack of polar groups in the repeating unit, is not able to form Langmuir or Langmuir-Blodgett (LB) films. This problem can be solved using PEs with hydrophilic groups arranged at regular distances within the polymer backbone. With acyclic diene metathesis (ADMET) polymerization, a tool for precise addition of polar groups after a certain interval of methylene sequence is available.

Crystallization of Poly(ethylene oxide) on the Surface of Aqueous Salt Solutions Studied by Grazing Incidence Wide-Angle X-ray Scattering.

We report the thin layer crystallization of high-molar mass poly(ethylene oxide) (PEO) on a liquid support using a 4 M KCO aqueous solution as a subphase. Because of the Hofmeister effect, PEO does not dissolve and remains at the surface during compression on a Langmuir trough. The transition from the flat pancake conformation upon compression of the spread polymer film to an entangled monolayer results in a plateau region of the Langmuir isotherm.

Chain Tilt and Crystallization of Ethylene Oxide Oligomers with Midchain Defects.

Many text books and publications do not focus on the necessity of chain tilting in crystalline lamellae of oligomers and polymers, a fundamental aspect of their crystallization already discussed by Flory. Herein we investigate the chain tilt of ethylene oxide oligomers (EOs) containing various midchain defects by WAXS, SAXS and solid state C MAS NMR spectroscopy. At low temperatures, one out of the two EO chains of EO--EO and EO-TR-EO containing a 1,3-disubstituted benzene or a 1,4-disubstituted 1,2,3-triazole defect in central position of the oligomer chain forms crystals and the other EO chain as well as the defect remain in the amorphous phase.

Proton conductivity and phase transitions in 1,2,3-triazole.

1,2,3-Triazole (TR) is a good proton conductor which is tidely related to formation of a hydrogen bond network along the N-HN trajectory and its self-dissociation into diH-1,2,3-triazolium and 1,2,3-triazolate. To gain a deeper understanding, the proton conductivity of TR is measured by impedance spectroscopy (IS) across its melting temperature and an additionally discovered solid-solid phase transition. The orthorhombic high temperature phase and the monoclinic low temperature modification are investigated by polarized optical microscopy, DSC- and WAXS measurements.

Self-organization of poly(ethylene oxide) on the surface of aqueous salt solutions.

It is demonstrated that stable Langmuir films of poly(ethylene oxide) (PEO) can be formed up to surface pressures of 30 mN m(-1) when potassium carbonate K2CO3 is added to the aqueous subphase. Generally, PEO homopolymer cannot stay on the water surface at a surface pressure ≥10 mN m(-1) due to its high water solubility. To prepare stable monolayer films, PEO can be modified with hydrophobic moieties.

Formation of 2D spherulites in Langmuir films of amphiphilic T-shaped liquid crystals.

Langmuir films of facial T-shaped amphiphilic liquid crystals were studied at the air-water interface. The liquid crystals were composed of three incompatible segments: a central rigid rodlike p-terphenyl (TP) group, two flexible hydrophobic n-alkyl terminal chains of identical length linked through ether bonds, and one hydrophilic lateral chain of three ethylene oxide units with a carboxyl end group. In order to determine the influence of the alkyl chain length on the characteristics of condensed films three TPs having n-alkyl chains with eight (TP8/3), ten (TP10/3) or 16 (TP16/3) carbon atoms were investigated.

Formation of structured polygonal nanoparticles by phase-separated comb-like polymers.

A simple approach using comb-like polymers that undergo nanophase separation between the polyester backbone and the stearoyl side chains is proposed for the preparation of structured non-spherical nanoparticles from a nanoemulsion. Depending on the degree of esterification of the OH groups of poly(glycerol adipate) differently ordered nanostructures is obtained. A perfect lamellar arrangement is obtained for polymers with a high degree of esterification and leads to spherical nanoparticles with an internal onion-like structure.

Langmuir and Langmuir-Blodgett films of multifunctional, amphiphilic polyethers with cholesterol moieties.

Langmuir films of multifunctional, hydrophilic polyethers containing a hydrophobic cholesterol group (Ch) were studied by surface pressure-mean molecular area (π-mmA) measurements and Brewster angle microscopy (BAM). The polyethers were either homopolymers or diblock copolymers of linear poly(glycerol) (lPG), linear poly(glyceryl glycidyl ether) (lPGG), linear poly(ethylene glycol) (lPEG), or hyperbranched poly(glycerol) (hbPG). Surface pressure measurements revealed that the homopolymers lPG and hbPG did not stay at the water surface after spreading and solvent evaporation, in contrast to lPEG.

Synthesis of well-defined graft copolymers by combination of enzymatic polycondensation and "click" chemistry.

Aliphatic polyesters having pendant azide groups were prepared by enzymatic polycondensation in the presence of lipase from Candida antarctica type B (CAL-B). The grafting reaction to the N(3)-functional polyester was carried out quantitatively at room temperature using copper-catalyzed azide-alkyne cycloaddition (CuAAC, "click" reaction) with monoalkyne-functional poly(ethylene oxide) (alkyne-PEO, M(n) = 750 g/mol). Furthermore, both enzymatic polycondensation and "click" reaction were carried out successfully in sequential one-pot reaction.

Langmuir monolayers and Langmuir-Blodgett films of 1-acyl-1,2,4-triazoles.

New 1-acyl-1,2,4-triazoles (ATs) with different n-alkyl chain lengths from C2 to C18 were synthesized. ATs with long n-alkyl chains (C12 and larger) are non-charged amphiphilic molecules with a polar triazole head group. The Langmuir isotherms of ATs at the air-water interface with 12 (DoT-C12), 14 (MyT-C14), 16 (PaT-C16) and 18 (StT-C18) carbon atoms in their n-alkyl chains were studied using surface pressure-mean molecular area (pi-mmA) measurements.

Comparison of the monolayer formation of fluorinated and nonfluorinated amphiphilic block copolymers at the air-water interface.

Series of fluorinated amphiphilic diblock copolymers poly(ethylene oxide)-b-poly(heptafluorobutyl methacrylate) (PEO-b-PHFBMA) and nonfluorinated analogue copolymers poly(ethylene oxide)-b-poly(n-butyl methacrylate) (PEO-b-PBMA) with different lengths of hydrophobic blocks were synthesized. Their interface properties at the air-water interface were investigated using surface pressure and X-ray reflectivity (XR) measurements on the Langmuir trough. The fluorinated species have shown a distinct transition from flat-lying to standing side chains, whereas the nonfluorinated ones have no indication for a significant amount of flat-lying side chains.

Hierarchical organization of poly(ethylene oxide)-block-poly(isobutylene) and hydrophobically modified Fe(2)O(3) nanoparticles at the air/water interface and on solid supports.

Langmuir monolayers and Langmuir-Blodgett (LB) film morphologies of block copolymers and hydrophobically modified iron oxide nanoparticles were studied by surface pressure-mean molecular area (pi-mmA) measurements and by tapping mode atomic force microscopy (AFM). The amphiphilic diblock copolymers consisted of a hydrophilic poly(ethylene oxide) (PEO) block and a hydrophobic poly(isobutylene) (PIB) block. The pi-mmA isotherm of PEO(97)-b-PIB(37) (the subscripts refer to the respective degrees of polymerization) at the air/water interface had an extended plateau reflecting the extension of PEO chains into the water subphase at a surface pressure of 10 mN.

Modification of a reverse microemulsion with a fluorinated triblock copolymer.

A w/o microemulsion consisting of n-decane, AOT, and water with a droplet volume fraction Phi=0.2 and a molar ratio of water to AOT omega=40 has been used as a model system to investigate the effect of added amphiphilic triblock copolymers on structure and conductivity of the system. Structure of the system is determined by small-angle X-ray scattering.

Influence of amphiphilic block copolymer induced changes in membrane ion conductance on the reversal of multidrug resistance.

Block copolymers are able to reverse multidrug resistance (MDR) of tumor cells by a yet unknown mechanism. The drug efflux system's direct and indirect inhibition mediated by polymer P-glycoprotein (Pgp) interactions or adenosine triphosphate (ATP) depletion, respectively, may be involved in MDR reversal as well as damage to the membrane barrier caused by polymer insertion into the membrane. To test the latter hypothesis, cellular drug accumulation was monitored in the presence of both overexpressed fluorescently labeled Pgp and different block copolymers.

Water surface covering of fluorinated amphiphilic triblock copolymers: surface pressure-area and X-ray reflectivity investigations.

Monolayers of ABA amphiphilic triblock block copolymers are studied using surface pressure-area and X-ray reflectivity (XR) measurements. The triblock copolymers are composed of long poly(ethylene oxide) (PEO) middle blocks with poly((perfluorohexyl)ethyl methacrylate) (PFMA) end blocks. The surface pressure-area isotherms of water-insoluble species show two pseudoplateaus.

Contact angle, WAXS, and SAXS analysis of poly(beta-hydroxybutyrate) and poly(ethylene glycol) block copolymers obtained via Azotobacter vinelandii UWD.

This study investigated and correlated physical properties and cell interactions of copolymers obtained by a poly(ethylene glycol) (PEG)-modulated fermentation of Azotobacter vinelandii UWD. PEGs with molecular weights of 400 and 3400 Da and di(ethylene glycol) (DEG) were used to modulate the bacterial synthesis of poly(beta-hydroxybutyrate) (PHB). The PHB crystallinity was determined by wide-angle X-ray scattering (WAXS).