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Simple ML2 [M = Fe(ii), Co(ii), Ni(ii)] complexes obtained from a perfluoroalkylamide derivative of 4-aminophenyl-2,2',6,2'-terpyridine spontaneously, yet anion selectively, self-assemble into gels, which manifest an unprecedented rapid gel strength recovery, viz. self-healing, and thermal rearrangement in aqueous dimethyl sulfoxide. The key factor for gelation and rheological properties emerges from the fluorine-fluorine interactions between the perfluorinated chains, as the corresponding hydrocarbon derivative did not form metallogels. The perfluoro-terpyridine ligand alone formed single crystals, while its Fe(ii), Co(ii) or Ni(ii) complexes underwent rapid gelation leading to highly entangled fibrillar networks visualized by electron microscopy. The thermodynamic parameters of gelation based on variable temperature NMR 1H and 19F resonances showed that gelation was enthalpically favourable and entropically disfavourable. The step strain rheological experiments revealed that the gels undergo rapid self-healing and the morphological features, thermal stability and mechanical properties were found to depend on the nature of the metal ion.

Simple ML2 [M = Fe(ii), Co(ii), Ni(ii)] complexes obtained from a perfluoroalkylamide derivative of 4-aminophenyl-2,2',6,2'-terpyridine spontaneously, yet anion selectively, self-assemble into gels, which manifest an unprecedented rapid gel strength recovery, viz. self-healing, and thermal rearrangement in aqueous dimethyl sulfoxide. The key factor for gelation and rheological properties emerges from the fluorine-fluorine interactions between the perfluorinated chains, as the corresponding hydrocarbon derivative did not form metallogels. The perfluoro-terpyridine ligand alone formed single crystals, while its Fe(ii), Co(ii) or Ni(ii) complexes underwent rapid gelation leading to highly entangled fibrillar networks visualized by electron microscopy. The thermodynamic parameters of gelation based on variable temperature NMR 1H and 19F resonances showed that gelation was enthalpically favourable and entropically disfavourable. The step strain rheological experiments revealed that the gels undergo rapid self-healing and the morphological features, thermal stability and mechanical properties were found to depend on the nature of the metal ion.

Simple ML2 [M = Fe(ii), Co(ii), Ni(ii)] complexes obtained from a perfluoroalkylamide derivative of 4-aminophenyl-2,2',6,2'-terpyridine spontaneously, yet anion selectively, self-assemble into gels, which manifest an unprecedented rapid gel strength recovery, viz. self-healing, and thermal rearrangement in aqueous dimethyl sulfoxide. The key factor for gelation and rheological properties emerges from the fluorine-fluorine interactions between the perfluorinated chains, as the corresponding hydrocarbon derivative did not form metallogels. The perfluoro-terpyridine ligand alone formed single crystals, while its Fe(ii), Co(ii) or Ni(ii) complexes underwent rapid gelation leading to highly entangled fibrillar networks visualized by electron microscopy. The thermodynamic parameters of gelation based on variable temperature NMR 1H and 19F resonances showed that gelation was enthalpically favourable and entropically disfavourable. The step strain rheological experiments revealed that the gels undergo rapid self-healing and the morphological features, thermal stability and mechanical properties were found to depend on the nature of the metal ion.

The effect of product design parameters on the formation and properties of an injection molded solid dosage form consisting of poly(ethylene oxide)s (PEO) and two different active pharmaceutical ingredients (APIs) was studied. The product design parameters explored were melting temperature and the duration of melting, API loading degree and the molecular weight (Mw) of PEO. The solid form composition of the model APIs, theophylline and carbamazepine, was of specific interest, and its possible impact on the in vitro drug release behavior. Mw of PEO had the greatest impact on the release rate of both APIs. High Mw resulted in slower API release rate. Process temperature had two-fold effect with PEO 300,000g/mol. Firstly, higher process temperature transformed the crystalline part of the polymer into metastable folded form (more folded crystalline regions) and less into the more stable extended form (more extended crystalline regions), which lead to enhanced theophylline release rate. Secondly, the higher process temperature seemed to induce carbamazepine polymorphic transformation from p-monoclinic form III (carbamazepine (M)) into trigonal form II (carbamazepine (T)). The results indicated that the actual content of carbamazepine (T) affected drug release behavior more than the magnitude of transformation.

In this study we present the rheological properties of a physically linked polymer network, composed of linear hydrophilic chains, modified with hydrophobic moieties in each end. Solutions of the polymer in ethanol-water mixtures showed Newtonian behaviour up to about 99 % ethanol, with the highest viscosity observed in a 1:1 mixture of ethanol and water. In pure ethanol, the polymer forms a thermo-responsive, non-Newtonian gel, which collapses upon addition of as little as 1 % water or heating to about 40 °C.

In this study we present the rheological properties of a physically linked polymer network, composed of linear hydrophilic chains, modified with hydrophobic moieties in each end. Solutions of the polymer in ethanol-water mixtures showed Newtonian behaviour up to about 99 % ethanol, with the highest viscosity observed in a 1:1 mixture of ethanol and water. In pure ethanol, the polymer forms a thermo-responsive, non-Newtonian gel, which collapses upon addition of as little as 1 % water or heating to about 40 °C.

The use of additives in crystallization of pharmaceuticals is known to influence the particulate properties critically affecting downstream processing and the final product performance. Desired functionality can be build into these materials, e.g. via optimized synthesis of a polymeric additive. One such additive is the thermosensitive polymer poly(N-isopropyl acrylamide) (PNIPAM). The use of PNIPAM as a crystallization additive provides a possibility to affect viscosity at separation temperatures and nucleation and growth rates at higher temperatures. In this study, novel PNIPAM derivatives consisting of both isotactic-rich and atactic blocks were used as additives in evaporative crystallization of a model compound, nitrofurantoin (NF). Special attention was paid to possible interactions between NF and PNIPAM and the aggregation state of PNIPAM as a function of temperature and solvent composition. Optical light microscopy and Raman and FTIR spectroscopy were used to investigate the structure of the NF crystals and possible interaction with PNIPAM. A drastic change in the growth mechanism of nitrofurantoin crystals as monohydrate form II (NFMH-II) was observed in the presence of PNIPAM; the morphology of crystals changed from needle to dendritic shape. Additionally, the amphiphilic nature of PNIPAM increased the solubility of nitrofurantoin in water. PNIPAMs with varying molecular weights and stereoregularities resulted in similar changes in the crystal habit of the drug regardless of whether the polymer was aggregated or not. However, with increased additive concentration slower nucleation and growth rates of the crystals were observed. Heating of the crystallization medium resulted in phase separation of the PNIPAM. The phase separation had an influence on the achieved crystal morphology resulting in fewer, visually larger and more irregular dendritic crystals. No proof of hydrogen bond formation between PNIPAM and NF was observed, and the suggested mechanism for

The use of additives in crystallization of pharmaceuticals is known to influence the particulate properties critically affecting downstream processing and the final product performance. Desired functionality can be build into these materials, e.g. via optimized synthesis of a polymeric additive. One such additive is the thermosensitive polymer poly(N-isopropyl acrylamide) (PNIPAM). The use of PNIPAM as a crystallization additive provides a possibility to affect viscosity at separation temperatures and nucleation and growth rates at higher temperatures. In this study, novel PNIPAM derivatives consisting of both isotactic-rich and atactic blocks were used as additives in evaporative crystallization of a model compound, nitrofurantoin (NF). Special attention was paid to possible interactions between NF and PNIPAM and the aggregation state of PNIPAM as a function of temperature and solvent composition. Optical light microscopy and Raman and FTIR spectroscopy were used to investigate the structure of the NF crystals and possible interaction with PNIPAM. A drastic change in the growth mechanism of nitrofurantoin crystals as monohydrate form II (NFMH-II) was observed in the presence of PNIPAM; the morphology of crystals changed from needle to dendritic shape. Additionally, the amphiphilic nature of PNIPAM increased the solubility of nitrofurantoin in water. PNIPAMs with varying molecular weights and stereoregularities resulted in similar changes in the crystal habit of the drug regardless of whether the polymer was aggregated or not. However, with increased additive concentration slower nucleation and growth rates of the crystals were observed. Heating of the crystallization medium resulted in phase separation of the PNIPAM. The phase separation had an influence on the achieved crystal morphology resulting in fewer, visually larger and more irregular dendritic crystals. No proof of hydrogen bond formation between PNIPAM and NF was observed, and the suggested mechanism for

Rheological properties of aqueous solutions and hydrogels fonned by an amphiphiIic star block copolymer poly(acrylic acid)-blockpolystyrene (PAAS4-b-PS6)4. were investigated as a function of the polymer concentration (Cp), temperature, and added saIt concentration. The water-soluble polymer synthesised by atom transfer radical. polymerization (ATRP) was found to fonn hydrogels at room temperature at polymer concentrations. Cp, over 22 gIL due to the interpolymer drophobic association of the PS blocks. Increasing Cp leads to stronger elastic networks at room temperature that show a gel-to-solution transition with increasing temperature. Increase of ionic strength decreases the moduli compared with the pure hydrogel but did not affect the gel-sol transition temperature significantly. Small-angle X-ray experiments showed two distinct scattering correlation peaks for samples above the gelling Cp, which indicates the aggregates fonmed due to hydrophobic association. Upon heating the intensity of the scattering correlation peaks was found to decrease indicating the loss of the network structure due to thermal motion.

Rheological properties of aqueous solutions and hydrogels fonned by an amphiphiIic star block copolymer poly(acrylic acid)-blockpolystyrene (PAAS4-b-PS6)4. were investigated as a function of the polymer concentration (Cp), temperature, and added saIt concentration. The water-soluble polymer synthesised by atom transfer radical. polymerization (ATRP) was found to fonn hydrogels at room temperature at polymer concentrations. Cp, over 22 gIL due to the interpolymer drophobic association of the PS blocks. Increasing Cp leads to stronger elastic networks at room temperature that show a gel-to-solution transition with increasing temperature. Increase of ionic strength decreases the moduli compared with the pure hydrogel but did not affect the gel-sol transition temperature significantly. Small-angle X-ray experiments showed two distinct scattering correlation peaks for samples above the gelling Cp, which indicates the aggregates fonmed due to hydrophobic association. Upon heating the intensity of the scattering correlation peaks was found to decrease indicating the loss of the network structure due to thermal motion.

Four generations of dendronized polymers with a methacrylate backbone and hydroxy-functionalized aliphatic polyester dendrons based on 2,2-bis(methylol)propionic acid were studied in solutions by rheological measurements, dynamic light scattering, turbidimetry, and H-1 NMR self-diffusion measurements to reveal the effect of increasing hydrophilicity and molecular size on their solution properties. The studied polymers were interesting new amphiphiles with a hydrophobic main chain and a hydrophilic shell. Evidence of aggregation upon the heating of the first-generation polymer in an aqueous solution was obtained by dynamic light scattering and turbidimetry, reflecting the effect of the hydrophobic polymer backbone, whereas the higher generation polymers did not show aggregation upon heating. Although the dimensions of the polymers were observed to increase with increasing generation, all the polymers exhibited low viscosities and Newtonian flow behavior in both aqueous and dimethyl sulfoxide solutions. The relative viscosities of the polymers in water and dimethyl sulfoxide showed that the conformation of the polymers was somewhat more open in dimethyl sulfoxide, and this led to higher viscosities than those in water, in agreement with the H-1 NMR diffusion measurements, by which the dimensions were found to be larger for the polymers dissolved in dimethyl sulfoxide., QC 20100914