Anionic Polymerization of Ethylene Oxide in the Presence of the Phosphazene Base Bu^tP₄ – Kinetic Investigations Using In‐Situ FT‐NIR Spectroscopy and MALDI‐ToF MS

Abstract

Fourier‐transform near‐infrared (FT‐NIR) fiber‐optic spectroscopy was successfully used to monitor the anionic polymerization of ethylene oxide (EO). Kinetic data are provided for the polymerization of EO with the sec‐BuLi/ButP4 initiating system under different reaction conditions. In addition, the influence of different initiators and reaction conditions on the polymerization of EO is investigated. Online monitoring using NIR spectroscopy reveals an unexpected induction period present in EO homopolymerizations as well as in the synthesis of PEO containing block copolymers with [Li/ButP4]+ counterions. The resulting polymers are characterized by size exclusion chromatography (SEC). A low‐molecular‐weight polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) diblock copolymer was synthesized to gain more insight into the observed induction period by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS) on samples taken during EO polymerization. The induction period is believed to be a result of different factors involved in the formation of active centers, for example, the break up of lithium alkoxide aggregates by the phosphazene base ButP4, and chain length effects. It depends on reaction temperature, concentration of the phosphazene base ButP4, as well as the structure of the initiator.SEC traces for EO homopolymerizations using different initiating systems at 50 °C.magnified imageSEC traces for EO homopolymerizations using different initiating systems at 50 °C.

Electrostatic hierarchical co-assembly in aqueous solutions of two oppositely charged double hydrophilic diblock copolymers

“…Three different samples of poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP 38 -b-PEO 211 , P2MVP 42 -b-PEO 446 , and P2MVP 71 -b-PEO 454 have been synthesised by sequential anionic polymerisation (polydispersity index, PDI < 1.05) by H. Schmalz (Bayreuth University) [12,27], followed by quaternisation with methyl iodide. [The subscripts correspond to the degree of polymerisation.]…”

Organophosphate-catalyzed bulk ring-opening polymerization as an environmentally benign route leading to block copolyesters, end-functionalized polyesters, and polyester-based polyurethane

“…In order to avoid metal contamination without any special purification steps, the organocatalytic approach has emerged as a powerful metal-free polymerization process in recent years. 7 Considerable effort has been directed toward the evaluation of various types of both organic acids/bases for the ROP of cyclic esters, 7-37 cyclic carbonates, [38][39][40][41][42][43] epoxides, [44][45][46][47] lactams, 48 cyclic (carbo)siloxanes, 49 cyclic phosphates, [50][51][52][53][54] etc. Regarding the ROP of cyclic esters, organic Brønsted acids, e.g., methane sulfonic acid (MSA) and triflimide, were found to be suited for the polymerization of lactones, [8][9][10][11][12][13][14][15][16][17][18][19] whereas organic bases, e.g., 1,8-diazadicyclo [5.4.0]undec-7-ene (DBU) and 4-dimethylaminopyridine (DMAP), were effective for the ROP of the lactide (LA).…”

Double‐Faced Micelles from Water‐Soluble Polymers

“…Poly(2-methylvinylpyridinium iodide)-block-poly(ethylene oxide), P2MVP 42 -b-PEO 446 , and poly(acrylic acid)-block-poly(acryl amide), PAA 42 -b-PAAm 417 , were synthesized by sequential anionic polymerization [26] (followed by quaternization with methyl iodide) and the MADIX process, [27] respectively (for details see the Supporting Information). Aqueous solutions of micelles were prepared by mixing diblock copolymer stock solutions.…”