Synthesis of polyethene–graft–polystyrene copolymers from linear polyethene-containing cyclopropane rings

Abstract

An efficient procedure to produce polyethene-graft-polystyrene (E-C3-graft-PS) copolymers by simple thermal treatment at 200 1C of polyethene (PE)-containing cyclopropane ring units (E-C3) in the presence of a high excess of styrene is reported. The high treatment temperature likely induces the breaking of the constrained cyclopropane rings, leading to the formation of radicals on the PE chains. The presence of styrene during the thermal treatment allows the formation of side polymer chains on the starting materials and, consequently, of graft copolymers. The graft copolymers that were obtained are efficient compatibilizers for polymer blends as was determined from scanning electron micrographs, which were used to examine the bulk morphologies of two blends: one composed of 50/50 PE and polystyrene (PS), and the other of 49/49/2 PE, PS and E-C3-graft-PS. Polymer Journal ( Keywords: blends; compatibilizers; cyclopropane rings; graft copolymers INTRODUCTIONThe incorporation of functional monomers into polyethene (PE) chains is one of the main academic and industrial goals of polymer chemistry because it allows the synthesis of new materials with many attractive properties. 1 Several polymerization methods have been developed to incorporate different monomers, such as styrene and methylmethacrylate, into PE chains. Nevertheless, because of the general inability of a single initiator to polymerize both ethene and functional monomers, graft and block copolymers usually have been synthesized by postpolymerization processes, including free-radical initiator, living anionic and transition metal-catalyzed polymerizations. [2][3][4][5][6][7] As it has been reported in the literature, PEs containing controlled amounts of methylene-1,2-cyclopropane and methylene-1,2-cyclopentane units (hereafter called E-C3) can be obtained by the polymerization of ethene with 1,3-butadiene using rac-[CH 2 (3-tert-butyl-1-indenyl) 2 ]ZrCl 2 activated by methylalluminoxane as a catalyst. [8][9][10][11][12] These PEs are technologically relevant because the presence of reactive cyclopropane rings in the chains discloses the possibility to obtain polymers with different properties. 13,14 For example, in a recent study by our group, we showed that it is possible to produce crosslinked PE by simple thermal treatments of E-C3 copolymers in the temperature range of 160-200 1C. 13 The process takes place in a feasible time (1 h) without using any initiator and without loss of polymer crystallinity; it produces crosslinked PE in conditions that can be compatible with industrial fabrication processes. The formation of crosslinking is generated by the breaking of the highly tensioned cyclopropane rings with the subsequent generation of radicals.The thermal treatment of E-C3 copolymers up to 160 1C in the presence of functional monomers able to give radical polymerization

Optoeletronic properties of poly(N‐alkenyl‐carbazole)s driven by polymer stereoregularity

“…Isotactic poly( N ‐butenyl‐carbazole) ( i ‐PBK), isotactic and syndiotactic poly( N ‐pentenyl‐carbazole) ( i ‐PPK and s ‐PPK), and poly( N ‐hexenyl‐carbazole) ( i ‐PHK and s ‐PHK) were synthesized by using homogeneous Ziegler‐Natta (Z‐N) polymerization …”

“…Isotactic poly(N-butenyl-carbazole) (i-PBK), isotactic and syndiotactic poly(N-pentenyl-carbazole) (i-PPK and s-PPK), and poly(N-hexenyl-carbazole) (i-PHK and s-PHK) were synthesized by using homogeneous Ziegler-Natta (Z-N) polymerization. [12][13][14][45][46][47][48][49][50] Rac-dimethylsilylbis(1-indenyl)zirconium dichloride (1)/MAO and diphenylmethylidene(cyclopentadienyl)-(9-fluorenyl)zirconium dichloride (2)/MAO (Scheme 2) were used as isospecific and syndiospecific catalytic systems, respectively.…”

Ethylene/1,3-butadiene cyclocopolymerization catalyzed by zirconocene systems

“…As an example, it was shown that it is possible to produce crosslinked polyethylene by simple thermal treatments of such copolymers [35,36]. Moreover, by using a similar procedure, polyethylene-graft-polystyrene copolymers were prepared by thermal treatment at 200°C of polyethylene samples containing cyclopropane rings in the presence of a high excess of styrene [37]. Both processes were generated by radicals formed at high temperature from the breaking of the constrained cyclopropane rings.…”

Cyclopropane Hydrocarbons from the SpringtailVertagopus sarekensis─A New Class of Cuticular Lipids from Arthropods

“…The residue was purified by argentation flash chromatography (SiO cis,cis-3,4,13,14-Bismethylene-24-methyldotriacontane (4). Cyclopropanation was performed according to a modified procedure of Pragliola et al 52 A solution of AlEt 3 (1 M in hexane) was added to a stirred solution of diene 21 (25 mg, 0.054 mmol, 1.0 equiv) and CH 2 I 2 (13 μL, 0.163 mmol, 3.0 equiv) in CH 2 Cl 2 (1 mL). After stirring for 17 h at rt, NaF (42 mg, 0.540 mmol, 1.0 equiv) and H 2 O (1 mL) were added to the reaction mixture.…”