Double-Crystalline Polyethylene-b-poly(ethylene oxide) with a Linear Polyethylene Block: Synthesis and Confined Crystallization in Self-Assembled Structure Formed from Aqueous Solution

Abstract

Narrowly distributed polyethylene-b-poly(ethylene oxide) diblock copolymers (PE-b-PEO) with a linear PE block were successfully synthesized by combination of click coupling reaction of azido-terminated polyethylene (PE−N3) and alkynyl-terminated poly(ethylene oxide) (PEO−CONHCH2CCH). PE−N3 derived from tosylation and subsequent substitution by sodium azide of hydroxyl-terminated PE (PE−OH) which was prepared by means of chain shuttling ethylene polymerization with 2,6-bis[1-(2,6- dimethylphenyl)imino ethyl] pyridine iron (II) dichloride (complex 1)/methylaluminoxane (MAO)/diethyl zinc (ZnEt2) and subsequent in situ oxidation with oxygen. PEO−CONHCH2CCH was synthesized through esterification the hydroxyl end-group on hydroxyl-terminated PEO (PEO−OH) with phosgene and subsequent amidation by propargyl amine. The self-assembly of three double-crystalline PE-b-PEO samples with different block length in water were investigated by laser light scattering (LLS) and transmission electron microscopy (TEM). It was found that, in water, a solvent selectively good for the PEO block, PE-b-PEO chains with proper PE block length could form spherical multicores micelles with the insoluble and crystallized PE blocks as the multicores and the soluble and swollen PEO blocks as the shell. These multicores in one micelle could reaggregate to a single-core as temperature increased. Differential scanning calorimetry (DSC) experiments showed that the crystallization of both PE and PEO blocks was intensely confined by the previously self-assembled structure of PE-b-PEO in aqueous solution.

Semi-crystalline polymethylene-b-poly(acrylic acid) diblock copolymers: aggregation behavior, confined crystallization and controlled growth of semicrystalline micelles from dilute DMF solution

“…Furthermore, in order to explore the inuence of solution pH value on the aggregation of PM-b-PAA, PM-b-PAA aqueous solution with desired pH value (2,5,7,9,12) was prepared by adding dropwise a small amount of HCl or NaOH aqueous solution (2 mol L À1 and 0.2 mol L À1 ) into the as-prepared 0.2 mg mL À1 aqueous solution without causing a distinct change in the solution volume. The nal micellar solutions were used for further characterization.…”

Synthesis and self‐assembly of amphiphilic star‐block copolymers consisting of polyethylene and poly(ethylene glycol) segments

“…As shown in Scheme , chain shuttling ethylene polymerization was conducted with 2,6‐bis[1‐(2,6‐dimethylphenyl) imino ethyl] pyridine iron (II) dichloride/MAO as catalyst and ZnEt 2 as chain shuttling agent to produce linear PE ‐ OH according to our previous report 21. In this case, at a ratio of Fe : Al : Zn = 1 : 750 : 500, a white product was obtained.…”

Facile functionalization of isotactic polypropylene by azide and alkyne groups for click chemistry application

“…The combination of NaH and propargyl bromide is also used to introduce alkyne functionality at room temperature,21 which is not correct for i ‐PP owing to the heterogeneous medium. Esterification of ‐OH with phosgene and the subsequent amidation by propargyl amine is another procedure to introduce aklyne group into a polymer chain, which can be operated at room temperature with high efficiency;5, 22 hence we decided to adopt this route for the synthesis of i ‐PP‐ g ‐≡. However, phosgene is an extremely toxic, irritating and corrosive gas.…”

“…Zhu and co‐workers synthesized hydroxyl (OH)‐terminated PE and obtained azide‐terminated PE (PE‐t‐N 3 ) after several steps. PE‐ b ‐PEO diblock copolymers were finally prepared by the coupling reaction of PE‐t‐N 3 with alkyne end‐functionalized poly(ethylene oxide) (PEO) 5…”