Synthesis and Characterization of Isotactic Poly(1-hexene)/Branched Polyethylene Multiblock Copolymer via Chain Shuttling Polymerization Technique

Abstract

Understanding from the underlying mechanism of chain shuttling polymerization (CSP) is limited due to scarceness of successful reports and incompetence of traditional characterization techniques to distinguish blocky structures. Here, a simple synthesis approach for production of an isotactic poly­(1-hexene)/branched polyethylene multiblock copolymer from a 1-hexene monomer is presented. Resulting copolymers can be easily characterized because of their solubility in most organic solvents. This novel blocky architecture is synthesized using ansa-ethylenebis­(1-η5-indenyl)zirconium dichloride and α-diimine nickel­(II) bromide catalysts. While the former participates in 1,2-enchainment of monomers and produces amorphous segments, the latter forms methylene sequences through chain walking reaction. A quasi-living polymerization is established by reversible transfer of growing chains between catalyst components, as manifested by narrowing molecular weight distribution. 13C NMR analysis confirms that the blocky structure can be tuned by adjusting polymerization conditions. Decrease of the crystallizable methylene sequence in the presence of CSA leads to a significant transparency of the product.

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

“…A branched polyethylene‐like polymer is obtained in Run 1, where the 1‐hexene monomer is polymerized alone in the presence of the catalytic system shown in Scheme . As we demonstrated in our earlier study, a regio‐irregular hyperbranched structure with backbone methylene sequences and side‐chains with various lengths is obtained. 1 H‐NMR spectra of the products after purification and extraction cycles are provided in the Supporting Information (Figures S1 and S2).…”

“…This proposition is approved by the presence of 39 distinct resonances in the 13 C‐NMR spectrum of 1‐hexene homo‐polymer. We have quantitatively identified and assigned all of these peaks as atom and triad sequences, by detailed investigation of the measured 13 C‐NMR, DEPT135, previously reported data and calculating chemical shifts in our previous publication . Accordingly, 1‐hexene homo‐polymer produced at this specific condition has about 137 branches per 1000 carbon atoms, mostly methyl and butyl type, and about 73 mol% of ethylene and propylene sequences as a consequence of the chain walking reaction.…”

“…DSC analysis results are listed in Table and Figure . The consecutive chain walking of the metallic center along the alkyl branch of the long olefinic monomers like 1‐hexene forms a short crystallizable methylene sequence . Therefore, a broad melting peak is associated with the DSC thermogram of poly(1‐hexene) made by the Brookhart‐type catalysts.…”

Performance of polyurea formulations against impact loads: A molecular dynamics and mechanical simulation approach

“…Although polyolefins dominate the world's polymer industry due to their very high production volume, the role of elastomers (specially polyurea and polyurethane) in the protective coatings industry is much more prominent. [1][2][3] Thermoplastic-elastomeric polyurea is formed by the reaction between two isocyanate and amine precursors during a condensation polymerization process. 4 The elastomer was synthesized, introduced, and commercialized in the late 1980s.…”

Stochastic Modeling of Poly(acrylate) Distributions Obtained by Radical Polymerization under High‐Temperature Semi‐Batch Starved‐Feed Conditions: Investigation of Model Predictions versus Experimental Data

“…Designing polymeric material for targeted applications requires an understanding of how operating conditions influence molecular structure. [3][4][5][6][7][8] Starved-feed freeradical solution semi-batch polymerization of acrylates at high temperatures is an industrially viable process for producing low molecular weight acrylic binder resins used in adhesives and automotive coatings due to the versatile functionality the acrylate family imparts for control of chemical and mechanical properties. [9,10] The polymerization rate and polymer properties are greatly influenced by a series of secondary reactions triggered by intramolecular chain transfer to polymer (known as backbiting) that forms reactive midchain radicals (MCRs), establishing branchpoints through monomer addition or reactive terminal double-bond chain ends via chain scission.…”