氮化硼纳米片利用超临界CO2流体的宏量制备研究

Boron nitride nanosheets (BNNS), also known as “white graphene”, hold the similar two dimensional structure as graphene and unique properties complementary to graphene, which makes it promising in a wide range of applications as new materials. Currently, there are still many problems to be solved in the large scale fabrication of BNNS. Liquid phase exfoliation and ball milling exfoliation are commonly used to produce BNNS in large scale. However, the liquid phase exfoliation involves a large amount of organic solvents, which leads to high pollutions. The ball milling exfoliation introduced too many defects into the products. To develop a green and large scale fabrication method with high efficiency, we intend to apply supercritical carbon dioxide to exfoliate boron nitride layers. In the proposed technique, supercritical carbon dioxide intercalates and diffuses between boron nitride layers. Then, the supercritical fluid expands rapidly and exfoliates boron nitride layers in the depressurization process. The diffusion kinetics of supercritical carbon dioxide between boron nitride layers will be studied. And the effect of reaction parameters and amplification on the quality of product will be investigated. As a result, an environmental-friendly and large scale chemical engineering process to fabricate BNNS is expected to be achieved.

氮化硼纳米片，又被称为“白色石墨烯”，具有和石墨烯类似的二维结构以及与石墨烯互补的独特性能，在新材料领域有着广泛的应用前景。但是现阶段氮化硼纳米片的宏量制备还存在很多问题需要解决。目前普遍采用的溶剂剥离法和球磨法存在高污染、产品缺陷多等问题。针对氮化硼纳米片的绿色、宏量、可控制备，申请者提出利用超临界CO2流体剥离氮化硼片层制备少层纳米片。本项目拟利用流体剪切力强化超临界CO2分子在氮化硼片层间插层并扩散，在快速泄压下，CO2克服层间作用力迅速溢出，实现对氮化硼片层的有效剥离。通过研究超临界CO2分子在氮化硼层间的界面扩散过程，考察原料以及反应条件对剥离性能的影响，并探索该剥离过程的放大效应，从而开发出绿色宏量制备氮化硼纳米片的化工过程。

氮化硼纳米片，又被称为“白色石墨烯”，具有和石墨烯类似的二维结构以及与石墨烯互补的独特性能，在新材料领域有着广泛的应用前景。但是现阶段氮化硼纳米片的宏量制备还存在很多问题需要解决。目前普遍采用的溶剂剥离法和球磨法存在高污染、产品缺陷多等问题。针对氮化硼纳米片的绿色、宏量、可控制备，申请者提出利用超临界CO2流体剥离氮化硼片层制备少层纳米片。本项目拟利用流体剪切力强化超临界CO2分子在氮化硼片层间插层并扩散，在快速泄压下，CO2克服层间作用力迅速溢出，实现对氮化硼片层的有效剥离。通过研究超临界CO2分子在氮化硼层间的界面扩散过程，考察原料以及反应条件对剥离性能的影响，并探索该剥离过程的放大效应，从而开发出绿色宏量制备氮化硼纳米片的化工过程。首先，采用过程强化的超临界CO2剥离技术，利用廉价的大块氮化硼原料成功剥离出氮化硼薄片。透射电镜及原子力显微镜表征结果显示制备的氮化硼薄片主要分布在5-9层，XRD和拉曼光谱证实得到的超临界CO2剥离得到的氮化硼纳米片具有晶型程度高，片层薄的特点。不仅如此，我们还进一步对氮化硼进行共价功能化改性处理，成功制备亲水性和亲油性的氮化硼纳米片。除了上述薄层BNNS材料外，还通过在BNNS表面上生长CNT来构建三维导热网络，从而进一步实现复合材料导热性能提升。