Research progress in the properties of polyvinyl alcohol modified with carbon dots
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摘要: 碳点(CDs)具有低毒性、水溶性、良好的生物相容性、易修饰性、优良的电化学活性和光学性能等优点,可用于高分子材料的改性,赋予其良好的光学性能及其他多种特殊性能。将其加入到聚乙烯醇(PVA)中,不仅可以使PVA力学性能和热稳定性得到有效改善,还赋予PVA一些新的性能,诸如电导率、介电性、热电性等多种电参数得到提高,呈现出荧光、磷光和耐紫外线等光学特性,同时具有抗菌性、抗氧化性和耐水性等一些优异的性能。使其在电磁屏蔽、存储器件、电容器、传感器、光学器件及功能性包装袋等领域崭露头角。本文就CDs改性PVA复合材料(CDs/PVA)性能的最新研究进展进行重点介绍,并对CDs/PVA复合材料未来应用方面进行了展望,对拓展其应用领域具有重要意义。Abstract: Carbon dots (CDs) have advantages such as low toxicity, water tolerance, good biocompatibility, easy modification, excellent electrochemical activity, and optical properties. CDs can be used for the modification of polymer materials, endowing them with good optical properties and various other functionalities. Adding CDs to polyvinyl alcohol (PVA) not only effectively improves the mechanical properties and thermal stability of PVA, but also endows PVA with new properties, such as improved conductivity, dielectric properties, thermoelectric properties, and other electrical parameters, optical properties such as fluorescence, phosphorescence, and UV resistance, antibacterial, antioxidant, and water resistance, which make PVA stand out in the fields of electromagnetic shielding, storage devices, capacitors, sensors, optical devices and functional packaging bags. This article focuses on the latest research progress in the properties of PVA modified with CDs (CDs/PVA), and prospects the future application of CDs/PVA, which is of great significance for expanding its application fields.
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Key words:
- polyvinyl alcohol /
- carbon dots /
- composite /
- properties /
- research progress
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图 3 (a) GQDs2-6/PVA中氢键形成示意图;(b) GQDs2-6/PVA中荧光(FL)和室温磷光(RTP)形成机制图[71] (将NaOH 和壳聚糖(NaOH∶壳聚糖=1∶2质量比) 的水溶液置于特氟隆内衬高压釜中在微波水热平行合成仪中于180℃下反应6 h制得物质命名为GQDs2-6)
Figure 3. (a) Schematic of hydrogen bonds formed in GQDs2-6/PVA; (b) Schematic of the fluorescence (FL) and room temperature phosphorescence (RTP) mechanisms in GQDs2-6/PVA[71] (The aqueous solution of NaOH and chitosan (NaOH∶chitosan=1∶2 mass ratio) was reacted in a Teflon-lined autoclave at 180℃ for 6 h in a microwave hydrothermal parallel synthesizer, and the obtained samples was named GQDs2-6)
S0—Ground state; S1—The lowest excited singlet state; Sn—The nth excited state of singlet state; T1—The lowest excited triplet state; Tn—The nth excited state of the triplet state; EX—Excite; ΔEST—Energy gap between T1 and S1; ISC—Intersystem crossing
图 4 (a) N掺杂碳点(N-CDs)/PVA复合膜的透射光谱;(b) N-CDs/PVA用作紫外线阻挡和可见光透明温室材料的示意图(插图为温室图片);(c) N-CDs/PVA复合膜阻断UV-A的示意图;(d) 紫外线阻断性能的演示:(I) N-CDs溶液直接在UV-LED手电筒上;(II) N-CDs溶液和UV-LED手电筒之间插入单层N-CDs/PVA复合膜(在载玻片上);(III) N-CDs溶液和UV-LED手电筒之间插入双层N-CDs/PVA薄膜(在载玻片上)[81]
Figure 4. (a) Transmittance spectra of N doped carbon dots (N-CDs)/PVA films; (b) Schematic illustration of N-CDs/PVA utilized as a UV-blocking and visible-transparent greenhouse material (Inset photograph shows a typical greenhouse); (c) Schematic demonstration of UV-A blocking by N-CDs/PVA film; (d) Demonstration of UV-blocking performance: (I) N-CDs solution directly on top of a UV-LED torch; (II) A single-layer of N-CDs/PVA film (on a glass slide) inserted between the N-CDs solution and the UV-LED torch; (III) A double-layer of N-CDs/PVA film (on a glass slide) inserted between the N-CDs solution and the UV-LED torch [81]
图 6 (a) 纯PVA膜断裂截面SEM图像;(b) 2 mL CDs (0.1wt%)/10 mL PVA (10wt%)复合膜SEM图像;(c) 8wt%纤维素纳米纤维(CNF)/PVA复合膜SEM图像;(d) 10 mL CNF (1wt%)/2 mL CDs (0.1wt%)/10 mL PVA (10wt%)复合膜SEM图像[90]
Figure 6. (a) SEM image of the fracture section of PVA film; (b) SEM image of 2 mL CDs (0.1wt%)/10 mL PVA (10wt%) film; (c) SEM image of 8wt%cellulose nanofibers (CNF)/PVA; (d) SEM image of 10 mL CNF (1wt%)/2 mL CDs (0.1wt%)/10 mL PVA (10wt%) film[90]
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