Triggered Structural Control of Dynamic Covalent Aromatic Polyamides: Effects of Thermal Reorganization Behavior in Solution and Solid States

Thermally rearrangeable aromatic polyamides (TEMPO-PA) and random copolyamides (TEMPO-PA-COOH) incorporating alkoxyamine moieties in the main chain were synthesized, and the effects of thermal reorganization behavior on their solution and solid-state structures were investigated. The hydrodynamic radius in solution decreased as the solution temperature increased because of the dissociation of the alkoxyamine unit. Additionally, the dry density of the thin films decreased as the fabrication temperature increased because of the suppression of polymer aggregation caused by the thermally induced radical crossover reaction. In addition, at the film surface of the random copolyamide containing hydrophobic TEMPO and hydrophilic 3,5-diaminobenzoic acid (DABA) units, the hydrophilicity decreased as the fabrication temperature increased. This is because hydrophobic TEMPO and hydrophilic DABA units tend to be discretely aggregated near the film surface to minimize the surface energy and suppress the hydrogen bonding via a radical crossover reaction during the thin-film fabrication process. The present study clearly shows that both the solution structure and the solid-state molecular aggregation structure of the dynamic covalent polymers can be easily controlled by a thermal trigger, and it provides a new method for controlling the higher-order structure of polymer solutions and solids

Budd-Chiari Syndrome: Two Cases with Different Courses

We report two cases of Budd-Chiari syndrome. Case 1: A 57-year-old man presented with leg edema and esophageal varices. Cavography showed obstruction of the inferior vena cava with antiphospholipid syndrome. Further, the patient showed positive serology for hepatitis C virus and consumed large quantities of alcohol. Percutaneous transluminal angioplasty was performed on this patient and anticoagulants administered; leg edema and esophageal varices were ameliorated although liver biopsy showed cirrhosis without evident congestion. More than 9 months since the diagnosis, restenosis of the inferior vena cava has not occurred. Case 2: A 73-year-old woman presented abdominal pain but no edema or varices. Cavography showed membranous obstruction of the inferior vena cava which required no therapy. Manifestation of portal hypertension was not present and liver function was maintained although liver biopsy showed obvious congestion. These cases showed untypical features against histopathology, and careful observation will be required for emergence of hepatocellular carcinoma