Water-Soluble, Self-Healing, and Debonding Primer for the Interface between Silicone Leather and Polydimethylsiloxane Composites.

The exceptional hydrophobicity and antifouling properties of polydimethylsiloxane (PDMS) composites have attracted extensive interest as a result of low surface energy. However, PDMS composites are hardly bound by common primers, greatly limiting their practical applications. To address this issue, an EPMS/VTMS (EV) primer synthesized by hydrolytic polycondensation of 3-[(2,3)-epoxypropoxypropyl]methyldiethoxysilane (EPMS) and vinyltrimethoxysilane (VTMS) in acidic conditions is proposed. Interestingly, the EV primer exhibits exceptional reactivity, self-healing capabilities, and strong adhesion to various substrates, including metals, plastics, and glass. The bonding aluminum plates are easily debonded by immersion in water without any residue left. Subsequently, the EV primer has been applied to the interface between silicone leather and the PDMS composite. Results show that the bonding strength for the silicone leather coated with the EV/PDMS composite is 16 times higher than that of the silicone leather modified with the PDMS composite. Meanwhile, the modified silicone leather exhibits impressive antifouling performance, including aqueous and oily stains, appreciable breathability, and excellent wear resistance, even if suffering from 20 000 cycles of abrasion. These excellent advantages for the modified silicone leather should be attributable to the synergistic effect of the EV primer and the PDMS composite. These findings pave the way to develop an ecofriendly debonding primer for PDMS composites, greatly facilitating applications of silicone leather.

Flexible transparent and hydrophobic SiNCs/PDMS coatings for anti-counterfeiting applications.

Silicon nanocrystals (SiNCs) have attracted considerable attention in many advanced applications due to silicon's high natural abundance, low toxicity, and impressive optical properties. However, little attention has been paid to fluorescence anti-counterfeiting applications based on lipophilic silicon nanocrystals. Moreover, it is also a challenge to fabricate aging-resistant anti-counterfeiting coatings based on silicon nanocrystals. Herein, this paper presents a demonstration of aging-resistant fluorescent anti-counterfeiting coatings based on red fluorescent silicon nanocrystals. In this work, lipophilic silicon nanocrystals (De-SiNCs) with red fluorescence were prepared first by thermal hydrosilylation between hydrogen-terminated silicon nanocrystals (H-SiNCs) and 1-decene. Subsequently, a new SiNCs/PDMS coating (De-SiNCs/DV) was fabricated by dispersing De-SiNCs into reinforcing PDMS composites with vinyl-capped silicone resin. Interestingly, the De-SiNCs/DV composites exhibit superior transparency (up to 85%) in the visible light range, outstanding fluorescence stabilities with an average lifetime of 20.59 µs under various conditions including acidic/alkaline environments, different organic solvents, high-humidity environments and UV irradiation. Meanwhile, the encapsulation of De-SiNCs is beneficial to enhancing the mechanical properties and thermal stability of De-SiNCs/DV composites. Additionally, the De-SiNCs/DV coating exhibits an excellent anti-counterfeiting effect on cotton fabrics when used as an ink in screen-printing. These findings pave the way for developing innovative flexible multifunctional anti-counterfeiting coatings in the future.

Luminescent Mechanism and Anti-Counterfeiting Application of Hydrophilic, Undoped Room-Temperature Phosphorescent Silicon Nanocrystals.

Silicon nanocrystals (SiNCs) have attracted extensive attention in many advanced applications due to silicon's high natural abundance, low toxicity, and impressive optical properties. However, these applications are mainly focused on fluorescent SiNCs, little attention is paid to SiNCs with room-temperature phosphorescence (RTP) and their relative applications, especially water-dispersed ones. Herein, this work presents water-dispersible RTP SiNCs (UA-SiNCs) and their optical applications. The UA-SiNCs with a uniform particle size of 2.8 nm are prepared by thermal hydrosilylation between hydrogen-terminated SiNCs (H-SiNCs) and 10-undecenoic acid (UA). Interestingly, the resultant UA-SiNCs can exhibit tunable long-lived RTP with an average lifetime of 0.85 s. The RTP feature of the UA-SiNCs is confirmed to the n-π* transitions of their surface C═O groups. Subsequently, new dual-modal emissive UA-SiNCs-based ink is fabricated by blending with sodium alginate (SA) as the binder. The customized anticounterfeiting labels are also prepared on cellulosic substrates by screen-printing technique. As expected, UA-SiNCs/SA ink exhibits excellent practicability in anticounterfeiting applications. These findings will trigger the rapid development of RTP SiNCs, envisioning enormous potential in future advanced applications such as high-level anti-counterfeiting, information encryption, and so forth.