Synthesis and characterisation of highly branched polyisoprene: exploiting the “Strathclyde route” in anionic polymerisation

Habibu, Shehu and Sarih, Norazilawati Muhamad and Mainal, Azizah (2018) Synthesis and characterisation of highly branched polyisoprene: exploiting the “Strathclyde route” in anionic polymerisation. RSC Advances, 8 (21). pp. 11684-11692. ISSN 2046-2069, DOI

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This work aimed at developing a synthetic route towards highly branched poly(isoprene) from commercially available raw materials, in good yield and devoid of microgelation, i.e., to prepare a completely soluble polymer via the versatile technique anionic polymerisation. The polymerisations were conducted under high vacuum conditions using sec-butyllithium as initiator at 50 °C in toluene. Toluene served both as a solvent and as a chain-Transfer agent. The polar modifier used was tetramethylethylenediamine (TMEDA), and a commercial mixture of divinylbenzene (DVB) was employed as the branching agent for the "living" poly(isoprenyl)lithium anions. The nature of the reaction was studied on the TMEDA/Li ratio as well as the DVB/Li ratio. The obtained branched polymers were characterised by triple detection size exclusion chromatography (SEC), proton nuclear magnetic resonance spectroscopy (1H NMR), differential scanning calorimetry (DSC) and melt rheology. Broad molecular weight distributions have been obtained for the highly branched polymer products. 1H NMR spectroscopy reveals the dominance of 3,4-polyisoprene microstructure. It was found that the complex viscosities and dynamic moduli of the branched samples were much lower compared to their linear counterparts. The results conform with earlier findings by the "Strathclyde team" for radical polymerisation systems. This methodology has the potential of providing soluble branched vinyl polymers at low cost using the readily available raw materials.

Item Type: Article
Funders: University of Malaya (UM): Fundamental Research Grant Scheme, FRGS (FP031-2014B) and Postgraduate Research Fund, PPP (PG193-2015B)
Uncontrolled Keywords: 1H NMR spectroscopy; Broad molecular weight distribution; Chain transfer agents; Commercial mixtures; High-vacuum conditions; Highly branched polymers; Proton nuclear magnetic resonance spectroscopy; Tetramethylethylenediamine
Subjects: Q Science > Q Science (General)
Q Science > QD Chemistry
Divisions: Faculty of Science > Department of Chemistry
Depositing User: Ms. Juhaida Abd Rahim
Date Deposited: 20 Aug 2019 07:05
Last Modified: 20 Aug 2019 07:05

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