Dual-Cross-Linked Supramolecular Polysiloxanes for Mechanically Tunable, Damage-Healable and Oil-Repellent Polymeric Coatings

Abstract

Polymeric coatings that show tunable mechanical strength, healing ability of mechanical damage, and proper liquid repellency will be promising in various areas across life and industry. However, the exploitation of such coating materials is largely limited by their molecular design. In this work, polymeric coatings with ion-controlled mechanics and coloration and damage-healing and oil-sliding properties have been demonstrated based on a supramolecular design of dual-cross-linked polysiloxanes. The coating color and mechanical properties can be adjusted by coordinative metal ions with various metal-ligand binding abilities. Dense and dynamic hydrogen bonds and coordination bonds lead to the ready healing ability and high durability of the coating. The extreme smoothness of the flat silicone coating facilitates not only the sliding of impinging oil but also the restoration of topological integrity from mechanical damage. The coating can be selectively patterned and applied to large-scale substrates by diverse coating operations, making it feasible for versatile applications.

Coordination‐Driven Assembly of Metal–Organic Framework Coating for Catalytically Active Superhydrophobic Surface

“…[ 17 ] While the PDMS‐Cat polymer (Figure S1, Supporting Information) was reported featuring polydimethylsiloxane (PDMS) backbones and terminal catechol moieties, demonstrating great flexibility, hydrophobicity, ability to coordinate with different metal ions, and adhesion toward diverse substrates. [ 15,18 ] Therefore, ZIF‐8 was selected as the model material to fabricate MOF coating, using PDMS‐Cat as a multifunctional polymer binder.…”

“…Meantime, the temperature sweep curves shown in Figure a specify that the coatings could undergo a structure change and are softened with ascending temperatures, when the loss moduli (G′′) gradually increased and exceeded G′. This feature is derived from the intrinsic properties of the PDMS‐Cat polymer, [ 15 ] which could not only benefit for realizing the thermal healing ability and thus damage tolerance of the coatings (Figure 3d), but also endow the coatings with good reprocessability. Moreover, micro‐hardness indentation demonstrates the relatively high modulus and hardness of these MOF coatings, with the 50 wt% ZIF‐8 loaded MOF coating showing the highest modulus of ≈654 MPa and the hardness of 36.8 MPa (Figure 3b and Table S2, Supporting Information).…”

“…However, the ZIF‐8/PDMS coating was not resistant to organic solvents due to the poor anti‐swelling property of the PDMS‐Cat polymer (Figure S10b, Supporting Information). [ 15 ]…”

“…PDMS‐Cat polymer was synthesized by previously reported one‐pot copolymerization of bis‐aminopropyl‐terminated poly(dimethylsiloxane) (PDMS, M n = 870, Gelest Inc.), isophorone diisocyanate, and dopamine hydrochloride with the molar ratio of 5:5.5:1. [ 15 ] Notably, the as‐prepared polymer was stored in a vial with N 2 protection at −20 °C to prevent the oxidation of catechol groups before use.…”

“…The coating is fabricated by various industrial‐scale coating techniques, for example, bar coating, dip coating, and spray coating, with a MOF‐polymer precursor consisting of the widely studied MOF material (zeolitic imidazolate framework‐8, ZIF‐8), and a previously reported catechol‐terminated polysiloxane‐urea copolymer (PDMS‐Cat). [ 15 ] This catechol‐functionalized polymer not only acts as the linker between MOF particles to induce the assembly of the MOF particles and thus improve the mechanical stability of the MOF coating, but also enables the surface hydrophobization of MOFs as well as the immobilization of the MOF coating onto various substrates. Particularly, the catechol moieties of the polymer show strong coordination with the surface open metal sites of MOF nanoparticles, and offers ample non‐covalent interactions with various solid substrates.…”