title: Use of carbon dots to enhance UV-blocking of transparent nanocellulose films.
abstract: High-efficient transparent UV-blocking nanocellulose (NC) films were successfully assembled by pressured-extrusion of the composites of carbon dots (CDs), 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radical mediated oxidized nanocellulose (ONC) and ZnO nanostructures. ONC nanofibrils were firstly extracted from bamboo fibers and subsequently prepared by applying TEMPO oxidation. The as-obtained CDs-ONC-ZnO films exhibited high visible light transparency, excellent thermal stability and enhanced UV-blocking properties. Compared to the previously designed NC-ZnO films, CDs-ONC-ZnO films presented significant increase of UV-blocking ratio (UVR) with the same amounts of ZnO. Moreover, the UVR of CDs-ONC-s-ZnO film with 4wt% sheet-like ZnO (s-ZnO) at 300nm and 225nm is 92.74% and 98.99%, better than the same condition of CDs-ONC-b-ZnO film added with belt-like ZnO (b-ZnO) and CDs-ONC-p-ZnO film added with commercial particulate ZnO (p-ZnO). An interesting discovery is that when adding 4wt% p-ZnO, the UVR of CDs-ONC-p-ZnO film is very close to the value of NC-s-ZnO film with the same amount of s-ZnO.
authors.affiliation: Research Center of Nano Science and Technology, Shanghai University, Shanghai 200444, PR China. Electronic address: fengxin@shu.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Feng
authors.affiliation: Research Center of Nano Science and Technology, Shanghai University, Shanghai 200444, PR China.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Research Center of Nano Science and Technology, Shanghai University, Shanghai 200444, PR China.
authors.forename: Yaoquan
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Research Center of Nano Science and Technology, Shanghai University, Shanghai 200444, PR China.
authors.forename: Miao
authors.initials: M
authors.lastname: Miao
authors.affiliation: Research Center of Nano Science and Technology, Shanghai University, Shanghai 200444, PR China.
authors.forename: Shaomei
authors.initials: S
authors.lastname: Cao
authors.affiliation: Research Center of Nano Science and Technology, Shanghai University, Shanghai 200444, PR China.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Fang
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry; D011837:Radiation-Protective Agents / Q000737:chemistry*; D014466:Ultraviolet Rays; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D011837:Radiation-Protective Agents; D002244:Carbon; D002482:Cellulose; D015034:Zinc Oxide
keywords: Bamboo; Carbon dots; Nanocellulose; Thermal stability; Transparent UV-blocking film