Ti-iminocarboxylate catalyzed polymerization of ethylene to highly crystalline, disentangled, ultrahigh molecular weight polyethylene

TitleTi-iminocarboxylate catalyzed polymerization of ethylene to highly crystalline, disentangled, ultrahigh molecular weight polyethylene
Publication TypeJournal Article
Year of Publication2023
AuthorsBodkhe, DV, Chikkali, SH
JournalEuropean Polymer Journal
Volume182
Pagination111725
Date PublishedJAN
Type of ArticleArticle
ISSN0014-3057
Abstract

Disentangled ultrahigh molecular weight polyethylene (d-UHMWPE) is a niche, highly sought-after, and an emerging class of polyethylene. However, the synthesis of d-UHMWPE is uncommon and is equally challenging. Here, we report a Ti-iminocarboxylate complex that produces d-UHMWPE under ambient polymerization conditions. Treatment of tetrakis(dimethylamido-titanium) [Ti(NMe2)4] with 2-((4-methoxybenylidene)amino)benzoic acid produced a novel titanium complex Cat.1 [bis-dimethylamido-Ti-(bis-iminocarboxylate)]. The identity of Cat.1 was unambiguously ascertained using a combination of 1-2D NMR spectroscopy and mass analysis. Cat.1 was activated using various cocatalysts, and MMAO (modified methylaluminoxane) outperformed the others. Screening of polymerization parameters suggested an Al/Ti ratio of 1000, 4 bar ethylene pressure, 35 degrees C temperature, and a polymerization time of 30 min as the optimal condition. Under the optimized polymerization conditions, Cat.1 polymerizes ethylene to ultrahigh molecular weight polyethylene with a weight average molecular weight (Mw) of 2.5 x 106 g/mol. The thermal behavior of the thus prepared material disclosed a highly crystalline [crystallinity chi (DSC) 96 %], strictly linear polyethylene. Detailed thermal analysis of the nascent polyethylene using a specifically designed DSC method revealed the existence of a high melting peak at 139-140 degrees C, which is a hallmark of disen-tangled UHMWPE. Thus, a homogeneous, single-site ethylene polymerization catalyst has been developed, which upon activation with MMAO produced highly crystalline d-UHMWPE.

DOI10.1016/j.eurpolymj.2022.111725
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)

5.546

Divison category: 
Polymer Science & Engineering
Database: 
Web of Science (WoS)

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