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

Abstract

Three difunctional benzoxazines were synthesized from cresol isomers (o-, m-, and p-methylphenols), 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, and formaldehyde. The ring-opening polymerization temperature decreases in the order of ortho-, para-, and meta-positions of methyl group for the benzoxazine monomers, whereas the glass transition temperature increases in the order of ortho-, para-, and meta-positions of methyl group for the resultant polybenzoxazines. In addition, the polybenzoxazines exhibit one-way dual-shape-memory behavior in response to changes in temperature, and the shape-memory effects are evaluated by tensile and bending tests with a temperature program based on glass transition temperature. The o-and p-cresol-based polybenzoxazines exhibit higher shape-memory performance than their m-cresol-based analogue/counterpart. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45443.

Dynamic mechanical and shape memory properties of copolymers based on polyetheramine‐type benzoxazines and diglycidylether of bisphenol‐A

“…For each copolymer, R f maintains a constant in four cycles, whereas R r gets a relatively low value in the first cycle, rises to a higher value in the second cycle and keeps a close value in the subsequent two cycles. The difference in R r between the first and the second cycles may be attributed to the motion constraints on the stretched specimens imposed by the upper fixed clamp and the lower movable clamp in Q800 DMA . In general, some chain conformation changes can result in (or be realized through) a macroscopic deformation movement of a SMP specimen in a full‐free state in a recovery process.…”

“…Recently, we synthesized a series of benzoxazines containing flexible –C–O–C– and –Si–O–Si– units, and the resultant polybenzoxazines exhibit thermally induced shape memory effect (SME) based on glass‐transition temperature ( T g ) . The shape memory properties of the polybenzoxazines are excellent under tensile and bending modes.…”

Vitrimers trigger covalent bonded bio-silica fused composite materials for recycling, reshaping, and self-healing applications

“…E-mail: krishchem05@gmail.com Over the past two decades, the research interest was directed towards benzoxazine based smart and advanced materials rather than developing alternative materials to conventional phenolic epoxy and their composites. Similarly, polybenzoxazines have been used to produce several smart materials such as smart coatings, 11,22,23 shape memory polybenzoxazines, [31][32][33][34] superhydrophobic surfaces, 35,36 and self-cleaning surfaces. 37,38 The occurrence of self-healing, repairing or recycling was common in nature.…”

Synthesis, ring-opening polymerization, and properties of benzoxazines based on o- and p-hydroxybenzyl alcohols

“…Recently, a series of benzoxazines were synthesized and the corresponding polybenzoxazines exhibit thermally induced shape memory effect (SME) based on glass transition temperature (T g ). [31][32][33][34][35][36] These polybenzoxazines possess suitable network architecture for shape memory, including crosslinking points, the Mannich bridge structure, and flexible chain segments containing C-O-C or Si-O-Si linkages. In the network, the crosslinked netpoints define the permanent shape, whereas the flexible chain segments act as stimuli-sensitive molecular switch providing additional temporary crosslinks to stabilize the temporary shape and leading to an entropy-driven recoiling of the chain segments.…”