不同相对分子质量木质素磺酸钠-石墨烯量子点的结构及性能研究

Study on the Structure and Properties of Sodium Lignosulfonate-graphene Quantum Dots with Different Molecular Weights

相对分子质量是影响聚合物性能的重要因素,以不同相对分子质量木质素磺酸钠和柠檬酸为原料制备了4种木质素磺酸钠-石墨烯量子点(SL/GQDs)。将相对分子质量不定、5000、10000、50000时,制备的SL/GQDs溶液分别标记为SL/GQDs1~SL/GQDs4。利用紫外可见光谱、红外光谱、透射电镜和荧光光谱对4种复合量子点进行了光学性能、结构与形貌的比较分析。研究结果表明:制备的SL/GQDs表面富含羰基、羟基等亲水基团,SL/GQDs1~SL/GQDs4的平均粒径分别为1.34、1.78、2.13和2.26 nm。相对分子质量50000的复合量子点SL/GQDs4总体性能最优,光致发光效应最强,对其进行金属离子检测,发现SL/GQDs4对不同金属离子均具有良好的选择性和灵敏性,在不同金属离子的共存体系中仍可检测Fe^(3+),可以作为检测Fe^(3+)的荧光探针。SL/GQDs4由于Fe^(3+)的加入,产生了荧光猝灭效应,当Fe^(3+)浓度在10~400μmol/L范围内,Fe^(3+)浓度与荧光强度(F/F0)存在良好负相关关系,通过数据拟合得Stern-Volmer线性回归方程F/F0=0.89366-0.00119C(Fe^(3+)),R2为0.98。

The relative molecular weight was an important factor affecting the performance of polymers.Four types of sodium lignosulfonate-graphene quantum dots(SL/GQDs)were prepared using sodium lignosulfonate with different relative molecular weights and citric acid as raw materials.The prepared SL/GQDs solutions were labeled as SL/GQDs1-SL/GQDs4,corresponding to relative molecular weights of undefined,5000,10000,and 50000,respectively.Optical properties,structures,and morphologies of the four composite quantum dots were compared and analyzed using UV-visible spectroscopy,infrared spectroscopy,transmission electron microscopy,and fluorescence spectroscopy,respectively.The results showed that the surface of SL/GQDs was rich in hydrophilic groups such as carbonyl and hydroxyl groups.The average particle sizes of SL/GQDs1-SL/GQDs4 were 1.34,1.78,2.13,and 2.26 nm,respectively.The composite quantum dot SL/GQDs4 with a relative molecular weight of 50000 exhibited the best overall performance and the strongest photo-induced luminescence effect.Therefore,SL/GQDs4 was selected for the detection of metal ions.It was found that SL/GQDs4 showed good selectivity and sensitivity towards different metal ions,and Fe^(3+)could still be detected in the coexistence system of different metal ions,which could serve as a fluorescent probe for Fe^(3+)detection.Furthermore,the addition of Fe^(3+)resulted in fluorescence quenching effect in SL/GQDs4.When Fe^(3+)concentrations were in the range of 10-400μmol/L,there was a good negative correlation between Fe^(3+)concentration and fluorescence intensity(F/F 0).The Stern-Volmer linear regression equation obtained by data fitting was F/F 0=0.89366-0.00119 C(Fe^(3+)),with R 2 of 0.98.