Search results for "ether"

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)…

Amphiphilic Linear-Hyperbranched Block Copolymers with Linear Poly(ethylene oxide) and Hyperbranched Poly(carbosilane) Block

2008

The synthesis of amphiphilic linear-hyperbranched block copolymers with a linear poly(ethylene oxide) (PEO) segment and a hyperbranched poly(carbosilane)s (PCS) block in a rapid three-step strategy is described, combining oxyanionic polymerization with carbosilane chemistry. A linear precursor block copolymer was synthesized via anionic polymerization of allyl glycidyl ether onto a commercial hydroxyl-terminated PEO, using its cesium alkoxide as macro-initiator. The resulting linear AB or ABA-type di- or triblock copolymers serve as polymer cores for the subsequent hydrosilylation polyaddition of an AB2-type carbosilane monomer. Di(allyl)methylsilane or methyldi(undec-10-enylsilane) were em…

Maleimide Glycidyl Ether: A Bifunctional Monomer for Orthogonal Cationic and Radical Polymerizations.

2015

A novel bifunctional monomer, namely maleimide glycidyl ether (MalGE), prepared in a four-step reaction sequence is introduced. This monomer allows for selective (co)polymerization of the epoxide group via cationic ring-opening polymerization, preserving the maleimide functionality. On the other hand, the maleimide functionality can be copolymerized via radical techniques, preserving the epoxide moiety. Cationic ring-opening multibranching copolymerization of MalGE with glycidol was performed, and a MalGE content of up to 24 mol% could be incorporated into the hyperbranched polymer backbone (Mn = 1000-3000 g mol(-1)). Preservation of the maleimide functionality during cationic copolymerizat…

Evaluation of Charge‐Regulated Supramolecular Copolymerization to Tune the Time Scale for Oxidative Disassembly of β‐Sheet Comonomers

2019

A multistimuli-responsive supramolecular copolymerization is reported. The copolymerization is driven by hydrogen bond encoded β-sheet-based charge co-assembly into 1D nanorods in water, using glutamic acid or lysine residues in either of the peptide comonomers. The incorporation of methionine as hydrophobic amino acid supports β-sheet formation, but oxidation of the thioether side-chain to a sulfoxide functional group destabilizes the β-sheet ordered domains and induces disassembly of the supramolecular polymers. Using H2 O2 as reactive oxygen species, the time scale and kinetics of the oxidative disassembly are probed. Compared to the charge neutral homopolymers, it is found that the oxid…

Size-dependent knockdown potential of siRNA-loaded cationic nanohydrogel particles.

2014

To overcome the poor pharmacokinetic conditions of short double-stranded RNA molecules in RNA interference therapies, cationic nanohydrogel particles can be considered as alternative safe and stable carriers for oligonucleotide delivery. For understanding key parameters during this process, two different types of well-defined cationic nanohydrogel particles were synthesized, which provided nearly identical physicochemical properties with regards to their material composition and resulting siRNA loading characteristics. Yet, according to the manufacturing process using amphiphilic reactive ester block copolymers of pentafluorophenyl methacrylate (PFPMA) and tri(ethylene glycol)methyl ether m…

Systematic Variation of the Degree of Branching (DB) of Polyglycerol via Oxyanionic Copolymerization of Glycidol with a Protected Glycidyl Ether and …

2017

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 …

Tuning the life-time of supramolecular hydrogels using ROS-responsive telechelic peptide-polymer conjugates

2019

Abstract The synthesis of multi-stimuli responsive peptide-poly(ethylene glycol) ABA-type conjugates is reported. The β-sheet encoded intramolecular folding and intermolecular self-assembly into 1D nanorods is based on a phenylalanine(F)-methionine(M)-histidine(H) FMHMHF hexapeptide sequence, and the supramolecular nanorods are stabilised by a shielding corona of hydrophilic PEG polymers. Interstrand crosslinking leads to the formation of physical networks and hydrogels at physiological pH and at room temperature. The thioether functional groups integrate oxidation responsive properties in the supramolecular polymer assemblies. We show that the glucose fuelled and glucose oxidase catalysed …

pH-Responsive protein nanoparticlesviaconjugation of degradable PEG to the surface of cytochromec

2020

Proteins represent a versatile biopolymer material for the preparation of nanoparticles. For drug delivery applications an acid-triggered disassembly and payload release is preferred. Herein, we present a protein nanoparticle system based on cytochrome c, which is surface-modified with acid-degradable polyethylene glycol (PEGylation). pH-Sensitivity was obtained through vinyl ether moieties distributed in the polyether backbone. When PEGylated, cytochrome c shows a different solubility behaviour in organic solvents, which allows for particle preparation using an emulsion-based solvent evaporation method. The resulting particles are stable under physiological conditions but degrade at acidic…

Synthesis and characterization of redox-sensitive polyurethanes based on L-glutathione oxidized and poly(ether ester) triblock copolymers

2021

Abstract Segmented polyurethanes, based on PCL-PEG-PCL copolymers, 1,4-diisocyanatobutane and l -glutathione oxidized, used as chain extender, were synthetized. Three different reactions conditions were investigated using three different copolymers having ɛ-CL/polyethylene glycol molar ratios equal to 12, 24 and 36 and three different reaction conditions. As investigated by size exclusion chromatography analyses and quantification of l -glutathione, the polymerization and the extension phase's efficiency depended on the ɛ-CL/PEG ratio and the extension phase's operating temperature. Three selected polyurethanes were characterized by spectroscopic, differential scanning calorimetry (DSC) and…