Biography:

Xin Ning is a graduate of the Peking University (BS, MS) in China and the Case Western Reserve University (PhD) in the USA. He is currently a professor of Materials Science and Textile Engineering in Qingdao, China. Ning has had a long career with the Kimberly-Clark Corporation in the USA, working in progressive technical and management roles leading to the Global Engineering Technical Leader. He joined the Qingdao University in 2016 as its founding director of the Industrial Research Institute of Nonwovens and Technical Textiles (IRINTT). Professor Ning’s research areas are nonwoven materials and processes, technical textile composites, hygiene and medical fabrics, polymer drug delivery systems, environmental engineering materials. 

Abstract:

Fibres have traditionally been made through melt or solution processes from macromolecules ranging from proteins to plastic polymers. Most of these fibres have crystalline structures formed by the orderly organization of the constituting molecules and distributed more or less uniformly across the fibre diameter. Segregation of discrete crystalline domains are extremely difficult due to the statistical nature of the formation and growth of these crystalline domains. Here we report a fibrous crystalline nano-sandwich where distinctly different crystalline regions are formed and aligned along the fibre longitudinal direction during the fibre spinning process and locked in place upon solidification. This approach employs side-by-side bicomponent nanofibre electro-spinning where the components are the enantiomerical pairs of PLLA and PDLA. We demonstrate the formation of the PLA stereo-complexes at the junction interphase of the two components through diffusion during the spinning process which subsequently crystallizes into sandwich fibre. The stereo-complex crystalline core in the fibre possesses a melting point 50oC higher than, and properties substantially different from, the regular PLAs at the fringe areas of the fibre. This nano-scale crystalline sandwich fibre structure could conceptually be applied to commercial bicomponent fibre spinning process where the dimensions are scaled to the micrometres instead of nanometers.