Biobased Nonisocyanate Polyurethanes as Recyclable and Intrinsic Self-Healing Coating with Triple Healing Sites

Abstract

Polymer coatings having high amounts of renewable carbon and self-healing properties are highly sought after in a sustainability perspective. We report here the development of bio-/ CO 2 -derived nonisocyanate polyurethane (NIPU) coatings which are recyclable and healable via three different types of healing mechanisms. These NIPUs contain furan rings in their main chain which after cross-linking with bismaleimides form organogels having a thermo-reversible sol−gel transition and solvent-borne coatings with improved properties. Judicial selection of the bismaleimide cross-linker structure enabled us to produce recyclable and intrinsic healable coatings mediated by heat (thermo-healing), moisture (moisture-healing), and, more interestingly, dry conditions at room temperature (self-healing). The intrinsic moisture-healing property of NIPU-based coatings is unprecedented and is mainly due to the presence of hydroxyl functionalities in the NIPU structure. The uniqueness of these cross-linked biobased NIPU as recyclable coatings having triple healing sites present in their structure gives these materials potential for sustainable and functional applications.

Structurally Diverse and Recyclable Isocyanate-Free Polyurethane Networks from CO2-Derived Cyclic Carbonates

“…Hence, the observed T g decrease was attributed to a moisture-induced plasticizing effect, anticipating that the interaction of PHUs with moisture is amplified compared to conventional PUs due to the presence of the pendent −OH groups. In fact, a moisture-assisted self-healing mechanism has been previously reported for a PHU CAN thanks to the H-bonding formed between the water molecules and the pendent −OH groups of the network . However, the dependence of the thermal and mechanical properties on the absorbed moisture was left for further investigation.…”

“…In fact, a moisture-assisted self-healing mechanism has been previously reported for a PHU CAN thanks to the H-bonding formed between the water molecules and the pendent −OH groups of the network. 48 However, the dependence of the thermal and mechanical properties on the absorbed moisture was left for further investigation. Moisture absorption by the PHU CANs prepared here was likely taking place already during the synthesis-cross-linking step and then continued during storage and reprocessing.…”

Divergent Aminolysis Approach for Constructing Recyclable Self-Blown Nonisocyanate Polyurethane Foams

“…The cross-linked foams are also repurposed into films or structural coatings by thermal treatment without necessarily requiring a catalyst. Similarly to a recent report on PHU coatings, our PHU materials (foams and reprocessed films) absorb a low content of air moisture that induces a strong hydroplasticization of the polymer. Although the mechanism behind the repurposing of the foams has to be further studied, this new process offers enormous perspectives for producing the next generation of greener and recyclable polyurethane foams.…”

“…All foams presented a comparable thermal decomposition behavior with a degradation temperature T d5% around 231–237 °C (Figures S18b and S19b), in the same range of T d5% measured for similar PHUs. , Importantly, the low weight loss between 50 and 200 °C (about 2–3 wt % depending on the sample; see SI for details) corresponded to the loss of absorbed water in PHU. As low amounts of absorbed water were recently demonstrated to strongly plasticize PHU-based coatings, the dried foamed samples (50 °C, vacuum, 24 h) were also analyzed by DSC, and data are collected in Table . Figure S20 compares the thermograms for the moistened and dried samples.…”

Reductive Amination of 5‐Hydroxymethylfurfural to 2,5‐Bis(aminomethyl)furan over Alumina‐Supported Ni‐Based Catalytic Systems

“…As an important building block platform, 5-hydroxymethylfurfural (5-HMF) can be transformed into various valued derivatives by the selective tailoring of its active C=O, À OH, and furan ring functional groups, such as 2,5-dimethylfuran, [1][2][3] 2,5dihydroxymethylfuran, [4][5][6] 2,5-bis(aminomethyl)furan (BAMF), [7][8][9] 2,5-diformylfuran, [10][11][12] 2,5-furandicarboxylic acid, [13,14] and other ring-opened compounds. [15,16] Among them, BAMF is considered as a promising bio-based monomer and utilized in the production of several kinds of bio-based polymers, such as polyurethane, polyamine, and polyurea, [17][18][19] with advantages in the gas barrier performance, miscibility, and processability. [20][21][22][23] Besides, the furan-based amine is also a promising intermediate in the pharmaceutical and food industry.…”