Unlocking features of locked-unlocked anionic polymerization. Issue 48 (20th November 2020)

• Record Type: Journal Article
• Authors: Li, Cun; Leng, Xuefei; Han, Li; Bai, Hongyuan; Yang, Lincan; Li, Chao; Zhang, Songbo; Liu, Pibo; Ma, Hongwei
• Is Part Of: Polymer chemistry. Volume 11:Issue 48(2020)
• Page Start: 7696
• Page End: 7703
• Publication Date: 2020-11-20
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/d0py01202e
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : Unlocking features of the locked-unlocked anionic polymerization were investigated and reported. Abstract : Due to unique characteristics of 1-(tri-isopropoxymethylsilylphenyl)-1phenylethylene (DPE-Si(O i Pr)3 ), quantitative locked (the living species became dormant for endcapping with DPE-Si(O i Pr)3 ) and unlocked (the dormant species regained the activity after adding the alkali metal alkoxides) anionic polymerization has been realized. In this work, the features of locked-unlocked anionic polymerization were carefully investigated with sequential feeding strategies. By combining the results from SEC, 1 H-NMR, MALDI-TOF-MS and DFT calculations, the main features of this mechanism were revealed as follows: (1) it is a kinetically controlled process ( k DS and k SS ) due to the inherent features of different living species. Comparable initiation and propagation rates are required to ensure the simultaneous chain growth from unlocked living species; (2) the transformation between locked and unlocked species depends on the alkalinity of the alkali metal alkoxides; the higher the alkalinity, the higher the unlocking efficiency. And promisingly, these findings may contribute to the modulation of molecular weight distribution and facilitate the preparation of position-defined functionalized polymers in the future.