Stretchable encapsulation plays a crucial role in expanding the applications of flexible electronics, particularly the large-area flexible displays. In this work, polydimethylsiloxane (PDMS) hybrid films with high stretchability, excellent transparency, and good barrier property are achieved by a simple process of SiO 2 doping and atomic layer infiltration (ALI). The doped SiO 2 improves the mechanical property and serves as reaction sites for the Al 2 O 3 infiltration. A clear “nucleation-filling-coating” mechanism of Al 2 O 3 ALI is proposed and elaborated in detail by in situ quartz crystal microbalance. The optimized PDMS hybrid films exhibit a relatively low water vapor transmission rate (WVTR) value of 1.81 × 10 −3 g m −2 day −1 and excellent mechanical reliability, where after 1000 cycles of the fatigue stretching test at 1% tensile strain the WVTR only slightly increases to 2.01 × 10 −3 g m −2 day −1 . Furthermore, the patterned quantum dots encapsulated with PDMS hybrid films still retain more than 50% photoluminescent intensity even after the stretching and storage in deionized water for 2400 h, which is ≈80 times longer than the pristine ones. Therefore, the proposed combined method of SiO 2 doping and ALI modification has great and practical implications for stretchable encapsulations for future flexible electronics.
Li Heng,Chen Limiao,Li Zhongbei,Wang Wengui,Liu Ying,Huang Xuemei,Liu Yaochi
The combination of nitrogen and phosphorus compounds has synergistic flame retardant effect, but the addition of low phosphorus content compounds is large, which affects the mechanical properties of polymers. Phosphorus ammonium polyphosphate (APP) with high phosphorus content and graphitic carbon nitride (g-C 3 N 4 ) doped with SiO 2 were used for the flame retardant (CN-Si-APP) of polyamide 6 (PA6). CN-Si-APPs with different APP/CN mass ratio (1, 2.5 and 4) and dosage (7 and 12 wt%) were blended with PA6 via a twin-screw extruder, and their flame retardancy was investigated by limiting oxygen index (LOI), UL-94 test, muffle furnace carbonization test and raman spectroscopy. When only APP added, the coefficient of water absorption (CWA) of composites increased and its tensile strength greatly reduced by nearly 37.1% to 35.39 MPa. The addition of g-C 3 N 4 inhibited the water absorption. When the addition dosage is 7%, the CWA of PA6/APP, PA6/CN-Si-APP2.5, PA6 and PA6/CN were 11.1, 6.86, 5.78 and 4.6%, respectively. SiO 2 effectively improved the dispersion of g-C 3 N 4 and the mechanical properties of composites. Thermogravimetric analysis (TGA) showed that the char residue of PA6 composites was improved significantly. The composite with 7 wt% CN-Si-APP4 passed the UL-94 V-0 rating. The LOI value and graphitization degree (I D /I G ) of PA6/12 wt% CN-Si-APP2.5 reached 28.7% and 2.93 respectively. Under the same dosage, the graphitization degree of CN-Si-APP2.5 (3.51) was higher than that of g-C 3 N 4 (3.98). The barrier protection of g-C 3 N 4 , catalytic effect of APP and SiO 2 crosslinking network promoted PA6 to form a dense and stable char layer, which protected PA6 composites from the flame. The strategy of synergistic flame retardant in this paper provides a valuable solution for reducing the amount of flame retardant.
危险品化学品经营许可证（带存储）