Facile and efficient formation of stereocomplex polylactide fibers drawn at low temperatures. (19th April 2022)

• Record Type: Journal Article
• Authors: Huang, Wei; Shi, Yamin; Wang, Peng; Yang, Qiu; Gobius du Sart, Gerrit; Zhou, Yuxiang; Joziasse, Cornelis A.P.; Wang, Ruyin; Chen, Peng
• Is Part Of: Polymer. Volume 246(2022)
• Publication Date: 2022-04-19
• Subjects: Stereocomplex polylactide -- In-situ reactive melt-spinning -- Transesterification reaction -- Stereo-block PLA copolymer -- Industrial-scale; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2022.124743
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Stereocomplex polylactide (SC-PLA) provides an effective route to improve heat-resistance through the formation of SC-PLA crystallites driven by hydrogen bonding interactions between poly(l -lactide) (PLLA) and poly(d -lactide) (PDLA). Great progress has been made in low molecular-weight SC-PLA compounds. However, the development of strategies for exclusive stereocomplexation in high molecular-weight (high-MW) PLLA/PDLA racemic blends quenched from isotropic melt remains challenging. In this study, in-situ reactive melt-spinning of commercially available high-MW PLLA/PDLA blend with a new transesterification catalyst (i.e., sodium octanoate in MB) was devised as an effective strategy to prepare blends containing stereo-block PLA (sb-PLA) copolymers. As a result, the sb-PLA copolymers restricted phase separation and further promoted relatively weak CH 3 ⋯ OC hydrogen bonding interactions, along with the development of the exclusive SC-PLA crystallites with low crystalline thickness ( L c ) in PLLA/PDLA/MB blend fibers drawn at low temperatures (≤102 °C). In contrast, extremely limited transesterification reaction in PLLA/PDLA melt led to the phase separation and the resultant separate domains of PLLA or PDLA restricted the occurrence of the CH 3 ⋯ OC hydrogen bonding interactions in the PLLA/PDLA blend fibers drawn at low temperatures (≤120 °C). Only when the PLLA/PDLA blend fibers were drawn at a high temperature (198 °C), the strong CH 3 ⋯ OC hydrogen bonding interactions could be formed, along with the formation of the exclusive SC-PLA crystallites with high L c . These findings provide a facile and effective strategy to develop industrial-scale PLA fibers containing the exclusive SC-PLA crystallites with improved heat-resistance. Graphical abstract: All SC-PLA fibers with improved heat-resistance were prepared via in-situ reactive melt-spinning and hot-drawing (≤102 °C) of linear high-MW PLLA/PDLA blend with a transesterification catalyst. Image 1 Highlights: All SC-PLA fibers with improved heat-resistance were prepared by in-situ reactive melt-spinning process. Sb-PLA copolymers were in-situ generated in PLLA/PDLA/MB melt through transesterification reaction. The sb-PLA copolymers restricted phase separation, promoting CH 3 ⋯ OC interactions in drawn fibers (≤102 °C). The CH 3 ⋯ OC interactions facilitated the formation of exclusive SC-PLA crystallites in drawn fibers (≤102 °C).