Imine or Secondary Amine-Derived Degradable Polyaminal: Low-Cost Matrix Resin with High Performance

Abstract

In recent years, much effort has focused on the development of degradable thermosets; however, high cost and relatively low performance have become serious barriers to their practical applications. In this work, degradable thermosets based on imine/secondary amine dynamic bonds were prepared by amine aldehyde condensation. Specifically, terephthaldehyde and various diamines were used as monomers, and triethylenetetramine was selected as a novel cross-linker to prepare the degradable polyaminal. Because of the −NH 2 and −NH−CH 2 −CH 2 −NH− groups in triethylenetetramine, a hybrid imine/imidazolidine cross-linking structure was obtained. Thanks to the rigid ring structure of imidazolidine, the polyaminal represents higher cross-linking density and mechanical properties compared with common thermosets based on Schiff base. Importantly, the present strategy reduced the preparation cost by ∼60% due to the usage of a quite low-priced cross-linker. The results showed that the obtained degradable polyaminal exhibits superior properties, T g (120−150 °C), T d (249−277 °C), and tensile strength (52−64 MPa). Moreover, the polyaminal/carbon fiber composite could be completely degraded under mild acidic conditions within 1 h, leading to a rapid and nondestructive recycling of valuable fiber. This study is believed to offer an alternate strategy to set up a green framework for highperformance degradable thermosets that can potentially be used in commercial and industrial production.

Biobased Dynamic Polymer Networks with Rapid Stress Relaxation

“…Associative DPNs have also been called vitrimers, a term first introduced by Leibler and co-workers in 2011, based on a transesterification reaction (TER) . Associative exchange mechanisms also include, for example, disulfide metathesis, , siloxane equilibration, Schiff base (imine) exchange, , and dioxaborolane metathesis . TERs have received the most attention, since this reaction is simple, and numerous commercially available epoxy monomers and carboxylic acids/anhydrides are readily available. − …”

Reprocessable, Reworkable, and Mechanochromic Polyhexahydrotriazine Thermoset with Multiple Stimulus Responsiveness

“…through the reversible depolymerization or exchange reactions of their dynamic cross-links [ 3 , 9 , 10 , 11 ]. So far, a number of CANs based on Michael addition [ 12 , 13 , 14 ], Diels-Alder reaction [ 15 , 16 ], disulfide exchange [ 17 , 18 , 19 ], imine metathesis [ 20 , 21 , 22 ], transesterification [ 23 , 24 , 25 ], olefin metathesis [ 26 , 27 ], silyl ether transalkoxylation [ 28 , 29 ], diketoenamine exchange [ 30 , 31 ], and dioxaborolane metathesis [ 32 , 33 ] have been proposed in the literature. Besides recyclability, many other adaptive properties of CANs were also investigated, such as reconfigurability [ 34 , 35 ], shape memory [ 36 , 37 ], and network topological transformation [ 18 , 25 , 38 ].…”

High Heat-Resistant and Degradable Polybenzoxazines with a Diacetal Structure

“…Moreover, the bands between 4.52 and 3.63 ppm attributed to H2, H2′, H3, and H3′ on the −CH 2 − of the diacetal structure still existed. Besides, in the 13 C NMR spectrum (Figure S4), the chemical shifts at 49. respectively. From the abovementioned analysis, the benzoxazine monomer, ACE-a, was successfully synthesized.…”

“…48 The synthetic route is illustrated in Figure 1, and the specific steps are shown in Supporting Information. Fourier transform infrared (FTIR), 1 H NMR, and 13 C NMR spectra of ACE are shown in Figure S1, S2, and S3.…”

“…FTIR spectra were obtained with a Nicolet-560 spectrometer in the range of 4000−400 cm −1 at a resolution of 4 cm −1 . 1 H NMR and 13 C NMR were carried out with Bruker Avance 400 Hz NMR spectrometers in DMSO-d 6 as solvent with tetramethylsilane as an internal reference. Differential scanning calorimetry (DSC) tests were conducted by a DSC Q20 (TA Instruments) at a heating rate of 10 °C/min under nitrogen atmosphere.…”