A Novel Consecutive Chain Transfer Reaction to p-Methylstyrene and Hydrogen during Metallocene-Mediated Olefin Polymerization

Abstract

This paper describes the first example of consecutive chain transfer reaction, first to p-methylstyrene (or styrene) and then to hydrogen, during metallocene-catalyzed propylene polymerization by rac-Me(2)Si[2-Me-4-Ph(Ind)](2)ZrCl(2)/MAO complex. The PP molecular weight is inversely proportional to the molar ratio of [p-methylstyrene]/[propylene] and [styrene]/[propylene] with the chain transfer constants of k(tr)/k(p) = 1/6.36 and 1/7.5, respectively. Although hydrogen does not influence the polymer molecular weight, it greatly affects the catalyst activity. Each PP chain formed contains a terminal p-methylstyrene (or styrene) unit. The terminal p-MS unit can be metalated to form a stable polymeric anion for living anionic polymerization to prepare new PP diblock copolymers, such as PP-b-PS, which are very difficult to prepare by other methods. The overall process resembles a transformation reaction from metallocene to living anionic polymerization.

Facile Creation of a Bionic Super‐Hydrophobic Block Copolymer Surface

“…Methylaluminoxane (MAO), dimethylsilyl-bis(2-methyl-4-(1-naphthyl)indenyl) zirconium dichloride, N-bromosuccinimide, copper bromide, and N,N,N¢,N¢,N¢-pentamethyldiethylenetriamine (PMDTA) were purchased and used as received. The first step was synthesis of styrene-terminated polypropylene (PP-t-St) using styrene as a chaintransfer agent during propylene polymerization with a highly isospecific ansa-metallocene catalyst [23]. In a typical reaction, a 500 mL stainless steel autoclave equipped with a mechanical stirrer was filled with toluene (100 mL), MAO (5.4 mL; 1.4 M in toluene), and styrene (2 mL).…”

A Greener Approach for Synthesis of Functionalized Polyolefins by Introducing Reactive Functionality into Ethylene Copolymers

“…The unsaturated ethylene/styrene/DVBP polymer was subsequently polymerized via anionic polymerization using n BuLi (Scheme 8). The resultant polymer showed increases in both the M n value and yield compared to the starting polymer and possessed unimodal molecular weight distribution [42]. An increase in the styrene content in the whole polymer (35.9 mol% → 50.6 mol%) as well as the intensity of the resonances ascribed to carbon of (more than) three styrene repeat units (T ββ ) in the 13 C NMR spectrum was clearly observed [41].…”

“…Introduction of p-methylstyrene (p-MS) should be effective for the subsequent post-modifications (to introduce additional functionality), because it has been known that the methyl group in p-MS can be used as the initiating fragment for anionic polymerization after treatment with s-BuLi [42] [43]. The terpolymerization of ethylene and p-MS with α-olefins could be achieved using 1 and 5, affording high molecular weight polymers with unimodal molecular weight distribution (Scheme 9) [44].…”

Polystyrene Chain Growth from Di-End-Functional Polyolefins for Polystyrene-Polyolefin-Polystyrene Block Copolymers

“…In the previous attempt (Scheme 1b), a typical ansa-metallocene rac-[Me 2 Si(2-methylindenyl) 2 ]ZrCl 2 was used as the catalyst in the CCTP process. In that case, the styrene moieties took part in the CCTP either as chain transfer agents or as comonomers [9,45], and so a dialkylzinc compound bearing the less reactive α-methylstyrene moiety was required. Although the α-methylstyrene moiety remained intact during the CCTP performed using rac-[Me 2 Si(2-methylindenyl) 2 ]ZrCl 2 , it was sluggishly involved in the subsequent anionic styrene polymerization.…”

“…Following the commercialization of OBCs by the Dow Chemical Company [6][7][8], Coates et al recently reported the preparation of PE/iPP (iPP = isotactic polypropylene) multiblock copolymers to enhance capabilities of plastic recycling [1]. In addition, connection of PO chains with other polymers such as polystyrene (PS) or polar monomer-based polymers to prepare diverse PO-based block copolymers has also been reported [9][10][11][12][13][14][15][16][17], with a typical example being PO-PS block copolymers, e.g., PS-block-poly(ethylene-co-1-butene)-block-PS (SEBS), which are commercially thermoplastic elastomer properties, SEBS is commonly employed in commodities such as rubbers and plastics [18][19][20][21][22], and its use in new specialized areas is also receiving growing interest [23][24][25][26][27][28][29]. In industry, SEBS is not produced directly from olefin and styrene monomers, but instead by a two-step process that involves the costly hydrogenation of the PS-block-polybutadiene-block-PS (SBS) copolymer produced by the living anionic polymerization of styrene and butadiene [30,31].…”