Search results for "Copolymer"
showing 10 items of 1003 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…
PEG-based Multifunctional Polyethers with Highly Reactive Vinyl-Ether Side Chains for Click-Type Functionalization
2011
Introduction of highly reactive vinyl ether moieties along a poly(ethylene-glycol) (PEG) backbone has been realized by copolymerization of the novel epoxide monomer ethoxy vinyl glycidyl ether (EVGE) with ethylene oxide (EO). A series of copolymers with varying structure (block and random) as well as EVGE comonomer content (5-100%) with molecular weights in the range of 3,900-13,200 g/mol and narrow molecular weight distributions (M-w/M-n = 1.06-1.20) has been synthesized and characterized with respect to their microstructure and thermal properties. The facile transformation of the vinyl ether side chains in click type reactions was verified by two different post polymerization modification…
Myrcenol-Based Monomer for Carbanionic Polymerization: Functional Copolymers with Myrcene and Bio-Based Graft Copolymers
2020
A bio-based hydroxyl group-containing diene monomer, silyl-protected β-myrcenol (MyrOSi), is introduced to the field of carbanionic polymerization. Polymerization in cyclohexane, using sec-butyllit...
Aminal Protection of Epoxide Monomer Permits the Introduction of Multiple Secondary Amine Moieties at Poly(ethylene glycol).
2019
In contrast to acetal groups, aminal moieties are almost unknown in polymer chemistry. The aminal-protected isopropyl-hexahydro-pyrimidine glycidyl amine (PyGA) for the anionic ring-opening polymerization (AROP) is introduced. The monomer is prepared in a two-step synthesis and can be polymerized in a well-controlled manner under AROP conditions. Several poly(ethylene glycol) block and triblock copolymers are synthesized in a molecular weight range from 2 700 to 11 400 g mol-1 with up to 11 mol% PyGA. The molecular weight distributions are monomodal with low dispersity (Đ = Mw /Mn ) below 1.2. After the polymerization, the acid-labile hexahydro-pyrimidine rings can be conveniently cleaved i…
Polyvinylferrocene-Based Amphiphilic Block Copolymers Featuring Functional Junction Points for Cross-Linked Micelles
2016
The synthesis of high-molecular-weight, well-defined poly(vinylferrocene)-block-poly(ethylene glycol) (PVFc-b-PEG) diblock copolymers (Mn = 13 000–44 000 g mol–1; Đ = 1.29–1.34) with precisely one allyl group at the junction point is introduced. Allyl glycidyl ether (AGE) was used to end-functionalize PVFc, resulting in hydroxyl functional macroinitiators for the oxyanionic polymerization of ethylene oxide. The self-assembly behavior of the amphiphilic PVFc-b-PEG copolymers in water has been investigated in a detailed manner, using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The redox activity of the PVFc block was confirmed by UV/vis spectroscopy, while cyclo…
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…