The utilization of dynamic covalent and noncovalent bonds in polymeric materials offers the possibility to regenerate mechanical damage, inflicted on the material, and is therefore of great interest in the field of self‐healing materials. For the design of a new class of self‐healing materials, methacrylate containing copolymers with acylhydrazones as reversible covalent crosslinkers are utilized. The self‐healing polymer networks are obtained by a bulk polymerization of an acylhydrazone crosslinker and commercially available methacrylates as comonomers to fine‐tune the Tg of the systems. The influence of the amount of acylhydrazone crosslinker and the self‐healing behavior of the polymers is studied in detail. Furthermore, the basic healing mechanism and the corresponding mechanical properties are analyzed.

The straightforward synthesis of a urea polymer network is presented. Commercially available monomers are polymerized using light-induced polymerization, resulting in networks crosslinked by hindered urea molecules. These moieties are reversible and, thus, can be converted into the starting compounds (that is, isocyanate and amine) by a simple thermal treatment. This process is monitored using differential scanning calorimetry as well as Raman and infrared spectroscopy. Furthermore, the self-healing ability of these polymer networks is investigated using scratch-healing tests as well as bulk-healing investigations using tensile testing. The resultant materials have a high E-modulus, are able to heal scratches at temperatures above 70°C multiple times and their mechanical properties can be partially regenerated. The underlying healing mechanism is based on the reversible opening of the urea bonds and exchange reactions between two functional groups, which were confirmed from a spectroscopic analysis. In summary, these new materials are a new type of intrinsically healable polymers and provide a first step toward hard and healable polymers.

A new polymeric material utilizing a highly efficient as well as reversible thiol‐ene click reaction is presented. For this purpose, a trithiol is reacted with a bisbenzylcyanoacetamide derivative resulting in the formation of a dynamic polymer network. The self‐healing ability of this novel material is tested by scratch healing experiments. Healing is found to take place from 60 °C onward. The underlying healing mechanism is studied in detail using temperature‐dependent Raman spectroscopy confirming the reversible opening of the thiol‐ene adducts. Additionally, the thermal and mechanical properties are investigated by differential scanning calorimetry, thermogravimetric analysis, and rheological measurements proving the network formation as well as its reversibility during the thermal treatment.

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A reversible thiol-ene click reaction is utilized to design novel self-healing polymers. These materials are based on a new methacrylate monomer featuring a benzylcyanoacetamide derivative, which is copolymerized with butyl methacrylate. Afterwards, the crosslinking is performed by the addition of a dithiol and a tetrathiol, respectively. Self-healing behavior is obtained by heating the crosslinked polymers to 100 8C (150 8C) for several hours and is monitored by scratch healing experiments utilizing an optical microscope. The thermal properties are studied in detail by differential scanning calorimetry as well as thermogravimetric analysis. Moreover, depth-sensing indentation measurements are performed to determine the mechanical properties. The healing process is based on the reversible cleavage/closing of the bonds (i.e., thiol-ene reaction), which could be demonstrated by Raman spectroscopy. V C 2017Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44805. Recently, also the reversible thiol-Michael addition was utilized for the fabrication of novel intrinsic self-healing polymers. 26 Kuhl et al. prepared a crosslinked network by the reaction of a bis-benzylcyanoacetamide linker with a trithiol, which features self-healing properties. 26 However, the applicable healing temperature was limited to 60 8C because of thermal instabilities at higher temperatures, which results in a depolymerization of the network accompanied by H 2 S formation and a subsequent irreversible thiol-ene click reaction.In order to overcome this problem, two new crosslinked polymers based on the reversible Michael addition were designed, Additional Supporting Information may be found in the online version of this article.