Intrinsic self-healing thermoset through covalent and hydrogen bonding interactions

Abstract

The intrinsic self-healing ability of polyketone (PK) chemically modified into furan and/or OH groups containing derivatives is presented. Polymers bearing different ratios of both functional groups were cross-linked via furan/bis-maleimide (Diels-Alder adducts) and hydrogen bonding interactions (aliphatic and aromatic OH groups). The resulting thermosets display tuneable softening points (peak of tan (δ)) from 90 to 137 °C as established by DMTA. It is found that the cross-linked system containing only furan groups shows the highest softening temperature. On the other hand, systems displaying the combination of Diels-Alder adducts and hydrogen bonding (up to 60 mol % of -OH groups) do not show any change in modulus between heating cycles (i.e. factually a quantitative recovery of the mechanical behaviour). It is believed that the novelty of these tuneable thermosets can offer significant advantages over conventional reversible covalent systems. The synergistic reinforcement of both interactions resists multiple heating/healing cycles without any loss of mechanical properties even for thermally healed broken samples

Electrically-Conductive Polyketone Nanocomposites Based on Reduced Graphene Oxide

“…Differential scanning calorimetry (DSC, TA Instruments, New Castle, DE, USA) was carried out by means of a TA DSC250 under N 2 in agreement with previous studies [32,35].…”

“…Another evidence that the chemical functionalization was successful can be found in the higher glass transition temperature (Tg) we measured for PK30-Gly-Gly (31.6 °C, Figure S1) compared to its precursor PK30 (−17.7 °C). This is possibly due to a combination of effect: a) the formation of pyrrole units after the Paal-Knorr reaction and the presence of hydrogen bonds between the Gly-Gly groups of different polymer chains [35,37], both contributing in the rigidity enhancement of the polymer matrix. Another evidence that the chemical functionalization was successful can be found in the higher glass transition temperature (T g ) we measured for PK30-Gly-Gly (31.6 • C, Figure S1) compared to its precursor PK30 (−17.7 • C).…”

“…In addition, it may be also performed without solvent or in various organic solvents depending on the physical and chemical properties of the amine compound. It is tolerant to a number of primary amines making this easy synthesis a fast, cheap, and appealing approach to create polymers with almost any desired pendant functional group [31,32,35,36]. The resulting functional polymers find use in different applications such as self-healing materials [37,38], emulsions with adhesive properties [39,40], and coating materials [41].…”

Advances in intrinsic self-healing polyurethanes and related composites

“…One key-perspective in the development of more advanced self-healing materials would be the combination of both covalent and non-covalent dynamic reactions within the same material, as reported in a few research papers. [25][26][27] Based on the last decades of development in self-healing polymers, it is important to classify them in an unambiguous way. Beside the classication upon extrinsic or intrinsic aspects, self-healing polymers can also be classied as autonomous, if healing occurs autonomously (without external trigger), or non-autonomous if external stimulus is required to achieve healing.…”

Epoxy resin doped with Coumarin 6: Example of accessible luminescent collectors

“…Moreover, epoxy resins and thermosets can be also rendered reworkable by using a series of thermally cleavable linkages. [32,33] Fluorophore doped epoxies have been already utilised in optical waveguides, light emitting diodes (LEDs) [34] and chromogenic materials [35] and attempts for polymer photostability under light exposure have been successfully made since years. [36] As far as LSC applications are concerned, they can offer outstanding physical attributes, including high physical strength, excellent adhesion to a variety of substrates, broad temperature resistance and the ability to cure in sections with controlled thickness.…”