Synthesis and microstructural characterisation of copolymers ofL‐lactide and trimethylene carbonate prepared using the SmI₂/Sm initiator system

Abstract

Polymerisation of trimethylene carbonate (TMC) and its copolymerisation with L‐lactide (LA) using the SmI2/Sm initiator system is reported. The reactions were carried out at different temperatures to optimize the reaction conditions. Reactivity ratio values evaluated using the Kelen–Tüdos method were 7.24 and 0.25 for LA and TMC, respectively. Microstructure of the copolymers and its change with the reaction time is reported using 1D (1H and 13C) and 2D heteronuclear multiple‐bond correlation NMR spectroscopic techniques. Electrospinning of the resulting copolymers was tried for the generation of fibres. Drastic deviations of the thermodynamic state from equilibrium were seen in the first heating cycle of the DSC trace of the electrospun fibres and are also reported here. Copyright © 2005 Society of Chemical Industry

Electrospinning: A Fascinating Method for the Preparation of Ultrathin Fibers

“…This process has immediate consequences for the dynamic and static mechanical properties of the fibers. [372] The curve for the nanofibers shows distinct deviations from the usual steplike changes in heat flow. [371] This phenomenon also occurs in semicrystalline polymers, but is concentrated in the amorphous regions.…”

“…In Figure 20, a differential scanning calorimetry (DSC) curve for nanofibers of semicrystalline PLA is compared to that for a slowly cooled bulk sample of PLA. [372] The curve for the nanofibers shows distinct deviations from the usual steplike changes in heat flow.…”

“…Differential scanning calorimetry (DSC) heating curves for: A) bulk PLA powder; B) electrospun PLA nanofibers. [372] Electrospinning Techniques Angewandte Chemie converted into the more ordered a phase by annealing the nanofibers at higher temperatures. [268] Of greater significance, especially with respect to mechanical properties, are the chain orientation and the orientation of the crystallites in the electrospun fibers.…”

Elektrospinnen: eine faszinierende Methode zur Präparation ultradünner Fasern

“…Für elektrogesponnene Fasern findet man in der Literatur nur wenige Informationen zu diesem Phänomen. Abbildung 20 zeigt ein Beispiel für Nanofasern aus teilkristallinem Polylactid; verglichen werden Kalorimeterkurven für Nanofasern und für Proben, die langsam abgekühlt wurden 372. Deutlich erkennbar sind bei den Nanofasern die Abweichungen im Wärmefluss von einem einfachen stufenförmigen Anstieg.…”

Effect of Configuration of a Bulky Aluminum Initiator on the Structure of Copolymers of <em>L</em>,<em>L</em>-Lactide with Symmetric Comonomer Trimethylene Carbonate

“…In preparation of Tmc/Lac copolymers the tin derivatives are the most widely used catalyst/initiator systems [12][13][14][15][16][17][18]. The valuable results have also been obtained with various aluminum [19], lanthanide [20][21][22], and zirconium complexes [23]. The homopolymerization rates of Tmc and Lac are substantially different.…”