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conditions. The sample shown in Figure 1a was prepared by heating the solution for 3 h at 80 C and casting the hot solution on a carbon-covered microscopy grid. Gray disks 5 nm in diameter were seen, which were identified as TiO 2 particles. The particles agglomerated into chains consisting of approximately 20 individual disks. Apparently the heating procedure had two effects involved in the film formation. First TiO 2 particles were formed in each block copolymer micelle. In a second step, the increased temperature caused the excess HCl to evaporate. The excess HCl is known, however, to be essential for stabilizing inverse diblock copolymer micelles during film formation. [10,11] As the HCl evaporates, the PEO block loses its ionic character and the kinetic as well as the thermodynamic stability of the diblock copolymer micelles is reduced because of the increased compatibility of the constituent blocks. Casting of films by simply allowing a drop of the solution to evaporate on a carbon-coated copper grid enabled the diblock copolymer micelles to react to the changing concentration and to transform from globular to worm-like micelles.This structural transformation could be prevented if substantial amounts of ions were still present in the micellar core. Figure 1b shows a TEM micrograph where individual TiO 2 particles are 5 nm in diameter and separated by approximately 30 nm. The image represents quasi-hexagonal close packing of spherical diblock copolymer micelles, as has been demonstrated previously. [5±7] The separation distance is controlled by the molecular weight of the diblock copolymer. In this particular case the solution was not heated for 3 h at 80 C, but was treated in a commercial microwave for 5 min. The microwave selectively heats the nanovolume of the inverse diblock copolymer as it only transfers its energy to the water molecules located in the micellar core. After 5 min of treatment the solution itself did not show any increase in temperature. Substantial amounts of HCl located in the core of each micelle are to be expected. Consequently, the micelles are stabilized and their structural relaxation times are reduced substantially. This allows the packing of individual spherical particles. Figure 1c shows TiO 2 particles formed under different conditions in the absence of a polymer compartment as formed by micelles. For this particular case a PS-b-PMAA diblock copolymer was dissolved in water with addition of Ti(OR) 4 . No micelles were present as water is a non-selective solvent for both blocks. Subsequent heating at 80 C for 2 h resulted in rather large TiO 2 particles 100 nm in diameter stabilized by adsorbed diblock copolymers. [9,11] In conclusion, it was demonstrated that monodisperse TiO 2 nanoparticles can be formed under the control of inverse polystyrene-block-poly(ethylene oxide) diblock copolymer micelles in toluene by hydrolyzation of titanium alkoxide. Variation of the sample preparation procedure allowed the coagulation of the diblock copolymer micelles loaded with 5 nm diamete...

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This article aims at preparing and characterizing efficiency of melt‐extruded polymer nanocomposites‐based drug delivery systems with tailored drug release properties. 5‐aminosalycylic acid (5‐ASA)‐loaded halloysite nanotubes (HNT)/plasticized starch nanocomposites were prepared and evaluated for the drug release, swelling characteristics, and degradability. The structure, morphology, and properties of the nanocomposites were characterized by using Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and UV‐visible spectrophotometry. The 5‐ASA and HNT hybrid formation is confirmed, as well as the presence of 5‐ASA within the HNTs and an excellent dispersion of the 5‐ASA/HNT hybrid in the thermoplastic starch matrix. The swelling of nanocomposites strongly depends on the temperature but not on pH. The degradability tests yield a stabilized weight loss of 24 wt%, which is ascribed to leaching of plasticizers. The presence of HNTs delays the drug release process. The observed in vitro drug release after 2 h is 37.2% for plasticized starch and 30.0% for the nanocomposites. Overall results indicate that the developed nanocomposite system can be a potential candidate for drug delivery applications. POLYM. ENG. SCI., 55:573–580, 2015. © 2014 Society of Plastics Engineers

Novel porous bionanocomposites based on halloysite nanotubes as nanofillers and plasticized starch as polymeric matrix were successfully prepared by melt-extrusion. Foaming was obtained by adding water as natural blowing agent, and by increasing the die temperature. Both the expansion ratio and the porosity increase with increasing die temperature. Addition of high water content allows reducing the foaming temperature. Moreover, the introduction of halloysite has double benefits: these fillers act both as a nucleating agent increasing the porosity and as a barrier agent increasing the proportion of small cells. Foams based on plasticized starch with a blend of glycerol and sorbitol loaded with 6 wt % of halloysite, extruded at 117 C, present the cellular structure and the mechanical properties required for scaffold applications.

Bionanocomposites based on halloysite nanotubes (HNT) as nanofillers and starch as polymer matrix were prepared by melt-extrusion process using glycerol as plasticizer and glycerol monostearate as lubricant. Scanning electron microscopic (SEM) images show homogenous dispersion of HNTs in starch matrix. A Fourier transform infrared analysis (FTIR) reveals the interaction between external hydroxyl groups of HNTs with C–O–C groups of starch. Upon halloysite addition, storage modulus, Young modulus and tensile strength increase without loss of ductility.

During the process of storing erythrocyte-containing blood products, components of the preservatives and modifications of the erythrocyte function cause disorders of the electrolyte and acid-base balance as well as a deficiency of 2,3-diphosphoglycerate (2,3-DPG). Thereby transitory hyperkalemias may occur in the course of a massive transfusion, if the patient has a shock or another disturbance of the regulating mechanisms caused by diabetes mellitus or a treatment with β-blockers or ACE inhibitors. During the treatment with blood components, hypocalcemia and hypomagnesemia may develop after a dose of more than 12 fresh frozen plasms (FFP) per hour, if the metabolism of citrate, which binds bivalent cations as a chelate, is disturbed by hypothermia, shock or during the anhepatic stage of a liver transplantation. As a consequence, a low-output syndrome as well as tachyarrhythmias and torsades de pointes may develop. Whether the decrease of the 2,3-DPG level with the accompanying leftward shift of the oxyhemoglobin dissociation curve brings about a deficiency of the oxygen supply of the organs, has not yet been verified by experiment. The studies presented rather point at morphological changes of the erythrocytes due to the storage as the cause of the disturbances of capillary perfusion. For this reason patients with impending organ failure or marked disturbances of the coronary or cerebral perfusion should be transfused with packed red blood cells (RBCs) not older than 14 days.