Thermally induced cationic polymerization of isobutyl vinyl ether in toluene in the presence of solvate ionic liquid

Radical polymerization of isobutyl vinyl ether (IBVE) was attempted with the aid of the interaction between the corresponding propagating radical and lithium cation (Li+). LiN(SO2CF3)2 (LiNTf2) and ester compounds, such as methyl methacrylate (MMA) and vinyl acetate (VAc), were added as a Li+ source and dissolving agent for LiNTf2, respectively. Homopolymers of cationically polymerizable IBVE were obtained despite the presence of radically polymerizable monomers such as MMA and VAc. Contrary to our expectation, the polymerization proceeded via not a radical mechanism but a cationic mechanism. However, this cationic polymerization was found to be unusual. In particular, the polymer yield increased with the polymerization temperature; successful polymerization was observed at 100 °C, whereas no polymerization occurred at lower temperatures such as at 0 °C. The behavior of the present system was therefore defined as “thermally induced cationic polymerization”. The mechanism of thermally induced cationic polymerization is still not clear, but it is assumed that the propagating cation is markedly stabilized through its interaction with the solvate ionic liquid formed between LiNTf2 and the Lewis base

Cationic homopolymerization of trans-anethole in the presence of solvate ionic liquid comprising LiN(SO2CF3)2 and Lewis bases

Cationic homopolymerization of a biomass-derived monomer, trans-4-methoxy-β-methylstyrene (trans-anethole: Ane), was achieved with a combination of bis(trifluoromethylsulfonyl)imide and solvate ionic liquid comprising lithium bis(trifluoromethylsulfonyl)imide and a Lewis base, such as ethyl acetate and diisopropyl ether (iPr2O). The number-average molecular weight (Mn) of the obtained poly(Ane) reached 15.6 × 103 by adding iPr2O in toluene at –10 °C. The solubility of poly(Ane) varied drastically with a change of solvent: the polymers obtained in CH2Cl2 were not completely soluble in common organic solvents such as toluene, chloroform, and tetrahydrofuran, except for 1,1,2,2,-tetrachloroethane (C2H2Cl4) at 140 °C, whereas the polymers obtained in toluene were soluble in these solvents. The 1H NMR spectrum measured in C2D2Cl4 at 140 °C revealed that the stereostructure of poly(Ane) depended significantly on the solvent and the temperature: a polymer with a more regulated stereostructure was obtained from polymerization in CH2Cl2 at –40 °C than those obtained by polymerization in toluene at –10 °C

Totally endoscopic pulmonary valve replacement

A 68-year-old man with a history of valve-sparing aortic root replacement and endoscopic aortic valve replacement was admitted to our hospital with dyspnea. Transthoracic echocardiography revealed severe pulmonary valve regurgitation. The patient had undergone cardiac surgery twice, through median sternotomy and right thoracotomy; therefore, we planned endoscopic pulmonary valve replacement via the left thoracic approach. The patient was placed in a modified right lateral decubitus position and underwent mild hypothermic cardiopulmonary bypass. An on-pump beating-heart technique was used during surgery. The 3D endoscopic system and trocars for surgical instruments were inserted through the left 3rd and 4th intercostal spaces. After incision of the pulmonary artery, the pulmonary cusps were resected. A 27-mm St Jude Medical Epic heart valve was implanted in the intra-annular position. Subsequently, the left atrial appendage was resected. The patient was discharged without complications. To our knowledge, this is the first case of totally endoscopic pulmonary valve replacement.</p