Dynamic mechanical and shape memory properties of polybenzoxazines based on aminopropyl‐terminated siloxanes

Abstract

Four siloxane-containing benzoxazine monomers and telechelic benzoxazine oligomers were synthesized from 1,3-bis(3aminopropyl)-1,1,3,3-tetramethyldisiloxane, a,x-bis(3-aminopropyl)polydimethylsiloxane, phenol, o-allylphenol, and formaldehyde. The length of the siloxane segment affects the polymerization reaction of the benzoxazine monomers and telechelic benzoxazine oligomers. The dynamic mechanical properties of the corresponding polybenzoxazines depend primarily on the structure of phenol and the length of the siloxane segment. The polybenzoxazines exhibit one-way dual-shape memory behavior in response to changes in temperature. The thermally induced shape memory effects of the polybenzoxazines were characterized by bending and tensile stress-strain tests with a temperature program based on their glass transition temperatures. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44121.

Effect of methyl position on the dynamic mechanical and shape‐memory properties of cresol‐based polybenzoxazines

“…Three difunctional benzoxazine isomers, o C‐aptmds, m C‐aptmds, and p C‐aptmds, were synthesized from cresol isomers ( o ‐, m ‐, p ‐cresols), APTMDS, and formaldehyde . The synthesis mechanism is shown in Scheme .…”

“…The absorption peaks at bands of 1465–1470 and 1322–1330 cm −1 are attributed to CH 2 bending and wagging vibrations, respectively, whereas the CH 3 bending vibration is observed at 1372 cm −1 . The bands at 1251–1253 cm −1 are ascribed to the SiCH 3 bending deformations, and the absorption peaks at 1056 cm −1 are assigned to the asymmetric stretching vibrations of SiOSi, whereas the bands at 794–796 cm −1 are owing to the stretching vibrations of SiC …”

“…In this study, the o ‐, m ‐, and p ‐cresol/APTMDS‐based benzoxazines are hereafter referred to as o C‐aptmds, m C‐aptmds, and p C‐aptmds, respectively, and they were synthesized by a procedure described previously (Scheme ) . The nuclear magnetic resonance (NMR) and FTIR data of the benzoxazines are given in the Supporting Information.…”

“…Of course, owing to the molecular design flexibility of benzoxazines, it is possible to prepare smart materials from pristine benzoxazines. Recently, we synthesized a series of benzoxazines containing flexible SiOSi and COC units, and the resultant polybenzoxazines exhibit thermally induced SMEs …”

“…Based on the previous work, we synthesized three benzoxazine isomers from cresol isomers ( o ‐, m ‐, and p ‐methylphenols), 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetramethyldisiloxane (APTMDS), and formaldehyde. Then, the three benzoxazine isomers were thermally polymerized into polybenzoxazines which exhibit shape‐memory properties, respectively.…”