Search results for "Comonomer"
showing 10 items of 74 documents
Water-soluble and redox-responsive hyperbranched polyether copolymers based on ferrocenyl glycidyl ether
2015
Water-soluble copolymers of ferrocenyl glycidyl ether (fcGE) and glycidol were prepared via anionic ring-opening multibranching polymerization (ROMBP). The resulting hyperbranched materials with molecular weights (Mn) of 3500 to 12 300 g mol−1 and relatively narrow molecular weight distributions (Mw/Mn = 1.40–1.69) exhibit both temperature- as well as redox-responsive behavior, which was studied via turbidity measurements. The cloud point temperatures (Tc) were adjusted between 45 and 60 °C through variation of the fcGE comonomer content. Additionally, these Tcs can be increased by the addition of an oxidizing agent. The extent of oxidation of the materials was quantified by Mosbauer spectr…
Effect of the Substituent Position on the Anionic Copolymerization of Styrene Derivatives: Experimental Results and Density Functional Theory Calcula…
2019
In a combined synthetic, kinetic and theoretical study, the living anionic copolymerization of styrene and its ring-methylated derivatives ortho-, meta-, and para-methylstyrene (MS) was examined by real-time 1H NMR spectroscopy in the nonpolar solvents toluene-d8 and cyclohexane-d12 as well as by density functional theory calculations. Based on the NMR kinetics data, reactivity ratios for each comonomer pair were determined by the Kelen–Tudős method and numerical integration of the copolymerization equation (Contour software). The reaction pathway was modeled and followed by density functional theory (DFT) calculations to validate and predict the experimentally derived reactivity ratios. Un…
Towards bio-based tapered block copolymers: the behaviour of myrcene in the statistical anionic copolymerisation
2019
To explore the potential of myrcene (Myr) as a bio-based monoterpene comonomer for styrenic copolymers and to establish its general applicability for the carbanionic copolymerisation, several statistical copolymerisations of myrcene and common monomers like isoprene (I), styrene (S) and 4-methylstyrene (4MS) were carried out in cyclohexane and monitored by in situ1H NMR spectroscopy. Real-time NMR kinetic studies permitted the determination of the reactivity ratios and the composition profile for each monomer combination. While the copolymerisation of Myr/I yielded a gradient copolymer and reactivity ratios of moderate disparity (rMyr = 4.4; rI = 0.23), the statistical copolymerisation of M…
Conventional Oxyanionic versus Monomer-Activated Anionic Copolymerization of Ethylene Oxide with Glycidyl Ethers: Striking Differences in Reactivity …
2022
Detailed understanding of the monomer distribution in copolymers is essential to tailor their properties. For the first time, we have been able to utilize in situ 1H NMR spectroscopy to monitor the monomer-activated anionic ring opening copolymerization (AROP) of ethylene oxide (EO) with a glycidyl ether comonomer, namely, ethoxy ethyl glycidyl ether (EEGE). We determine reactivity ratios and draw a direct comparison to conventional oxyanionic ROP. Surprisingly, the respective monomer reactivities differ strongly between the different types of AROP. Under conventional oxyanionic conditions similar monomer reactivities of EO and EEGE are observed, leading to random structures (rEO = 1.05 ± 0…
A Challenging Comonomer Pair: Copolymerization of Ethylene Oxide and Glycidyl Methyl Ether to Thermoresponsive Polyethers
2014
Motivated by the oxygen-rich and fully amorphous structure of poly(glycidyl methyl ether) (PGME), a series of thermoresponsive poly(glycidyl methyl ether-co-ethylene oxide) copolymers P(GME-co-EO) with molecular weights in the range of 3000–20 000 g mol–1 were synthesized by the activated monomer polymerization technique. Tetraoctylammonium bromide (NOct4Br) was employed as an initiator in combination with triisobutylaluminum (i-Bu3Al) as a catalyst under mild conditions. Polyethers with varying GME content between 31 and 100 mol % were obtained. Triad sequence analysis using 13C NMR spectroscopy proved that no pronounced block structure was obtained. Differential scanning calorimetry (DSC)…
Vinyl ferrocenyl glycidyl ether: an unprotected orthogonal ferrocene monomer for anionic and radical polymerization
2015
The first orthogonal ferrocene monomer, vinyl ferrocenyl glycidyl ether (VfcGE), for both anionic and radical polymerization – without the need of a protection group – is presented. Anionic ring-opening copolymerization of VfcGE and ethylene oxide (EO) generates stimuli-responsive, multifunctional poly[(vinyl ferrocenyl glycidyl ether)-co-(ethylene oxide)] (P[VfcGE-co-EO]) copolymers (molecular weights of ca. 7500 g mol−1 and low molecular weight dispersities (Đ ≤ 1.14)). The amount of the equimolar ferrocenyl and vinyl groups are controlled by the comonomer ratio up to 15.4 mol% VfcGE. The pendant vinyl groups of P[VfcGE-co-EO] were post-modified with 3-mercaptopropionic acid via thiol–ene…
Cationic Copolymerization of 3,3-Bis(hydroxymethyl)oxetane and Glycidol: Biocompatible Hyperbranched Polyether Polyols with High Content of Primary H…
2015
The cationic ring-opening copolymerization of 3,3-bis(hydroxymethyl)oxetane (BHMO) with glycidol using different comonomer ratios (BHMO content from 25 to 90%) and BF3OEt2 as an initiator has been studied. Apparent molecular weights of the resulting hyperbranched polyether copolymers ranged from 1400 to 3300 g mol(-1) (PDI: 1.21-1.48; method: SEC, linear PEG standards). Incorporation of both comonomers is evidenced by MALDI-TOF mass spectroscopy. All hyperbranched polyether polyols with high content of primary hydroxyl groups portray good solubility in water, which correlates with an increasing content of glycerol units. Detailed NMR characterization was employed to elucidate the copolymer …
Stimuli-Responsive Tertiary Amine Functional PEGs Based on N,N-Dialkylglycidylamines
2014
Amine-functional poly(ethylene glycol) (PEG) copolymers have been prepared that exhibit thermo- and pH- responsive behavior in aqueous solution. Three novel tertiary di(n-alkyl)glycidylamine monomers have been introduced for anionic ring-opening copolymerization (AROcP) with ethylene oxide (EO): N,N-di(n-butyl)glycidylamine (DButGA), N,N-di(n-hexyl)glycidylamine (DHexGA), and N,N-di(n-octyl)glycidylamine (DOctGA). Via controlled AROcP we synthesized well-defined (Mw/Mn = 1.05–1.14), water-soluble block- and gradient-type PEG copolymers, containing up to 25 mol % of the respective dialkylglycidylamine comonomer. Molecular weights ranged from 4900 to 12 000 g mol–1. Detailed in-situ 1H NMR ki…
Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization
2014
Oxovanadium(IV) complexes with (ONNO)-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H2salen = N,N'-ethylenebis(salicylideneimine), H2aceten = N,N'-ethylenebis(2-hydroxyacetophenoneimine), H2acacen = N,N'-ethylenebis(acetylacetonimine), H 2 acetph = N ,N ' -phenylene-1,2-b is (2-hydroxyacetophenoneimine)), were the first time investi- gated in ethylene polymerization and ethylene/1-octene copo- lymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization up- on activation with EtAlCl2 and they give high molecular weight linear polyethylenes. Their activity in copolymeriza- tion was found relatively low. However,…
Ethylene homo- and copolymerization catalyzed by vanadium, zirconium, and titanium complexes having potentially tridentate Schiff base ligands
2021
Abstract New potentially tridentate Schiff base ligands, 2-[({4-[(3-N,N-dimethylamino)propyl] phenyl}imino)methyl]-4,6-di-tert-butylphenol (L1H) and 2-[{2-(N-phenyl-N-methylaminomethyl)-phenylimino}-methyl]-4,6-di-tert-butylophenol (L2H) were prepared and after deprotonation they were reacted with VOCl3 or MCl4 (where M = Zr or Ti) to produce corresponding complexes (L1-V, L2-V, L1-Zr, L2-Ti) with good yields. All new compounds were characterized by the 1H and 13C NMR as well as FTIR spectroscopic methods. Upon activation with Et2AlCl or EtAlCl2, both the vanadium complexes exhibited exceptionally high catalytic activities in the ethylene polymerization (up to 69,000 kg/(molV⋅h) for L1-V an…