Search results for "Copolymer"
showing 10 items of 1003 documents
Polymer supported synthesis of mixed ligand complexes
2003
A series of novel polymer-supported mixed ligand complexes were synthesized and studied. Two percent divinyl benzene (DVB)-crosslinked polystyrene supports were synthesized by the suspension copolymerization technique. An ethylene diamine group was anchored onto the support and the corresponding copper complexes were prepared. The ligating functions like phthalate, acetate, and oxalate groups were introduced, and mixed ligands complexes were synthesized. The resultant polymer supported mixed ligand complexes were characterized by UV-Vis, IR, and EPR methods. The stability constants dictate the formation of these complexes on polymer support. Spectral results gave information about the struc…
Hairy Aramide Rod−Coil Copolymers
2010
We have synthesized monodisperse “hairy rod oligomers” based on oligo(p-benzamide)s carrying alkyl side chains and conjugated them with polydisperse poly(ethylene glycol) (PEG) chains. The well-defined oligomers were synthesized from 4-amino-2-hexyloxybenzoic acid using a commercial peptide synthesizer. The PEG conjugated hairy rod−coil block copolymers self-assemble in polar and nonpolar organic solvents. The self-organization in solution was investigated by dynamic light scattering (DSL) and transmission electron microscopy (TEM) as a function of solvent, equilibration time, and polarity of the substrate. Individual fibers and fiberlike bundles of aggregates could be observed. As all hydr…
Microstructure analysis of biocompatible phosphoester copolymers
2013
Copolymers with varying compositions of 2-ethoxy-2-oxo-1,3,2-dioxaphospholane (EEP) and 2-ethoxy-4-methyl-2-oxo-1,3,2-dioxaphospholane (EMEP) have been synthesized via 1,5,7-triazabicyclo[4.4.0]dec-5-ene-catalyzed anionic ring-opening polymerization. The molecular weights and comonomer ratios were well controlled and polymers with reasonable molecular weight distributions (<1.5) were obtained in all cases. The copolymers were investigated by 1H and 31P NMR spectroscopies to determine the underlying microstructure via detailed dyad analysis. The copolymers were found to be nontoxic to HeLa cells. Furthermore, the obtained copolymers of EEP and EMEP show thermoresponsive properties, i.e., exh…
Poly(phosphonate)-mediated Horner–Wadsworth–Emmons reactions
2015
A novel, general protocol for a polymer-mediated Horner–Wadsworth–Emmons (HWE) reaction is reported. The polyvalent polymeric reagent was prepared via acyclic diene metathesis (ADMET) polymerization. Homo- and copolymers of reactive poly(phosphonate)s with molecular weights up to 40 000 g·mol−1 and molecular weight dispersities Đ < 2 were successfully synthesized. Subsequent application of these polymers in the HWE reaction to prepare a library of aromatic α,β-unsaturated ketones (chalcons) has proven to be an efficient synthetic pathway to minimize purification efforts, as the polymeric side-product can be removed by simple precipitation. In this paper we also demonstrate for the first tim…
RAFT-polymerized poly(hexafluoroisopropyl methacrylate)s as precursors for functional water-soluble polymers
2014
Post-polymerization modification of well-defined precursor polymers is a versatile tool to obtain multifunctional water-soluble polymers that cannot be synthesized by common polymerization techniques. For the first time, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIPMA) based homo and block copolymers were synthesized via RAFT polymerization to provide precise precursors for the post-polymerization modification of the 1,1,1,3,3,3-hexafluoroisopropyl ester side chains with water-soluble amines (methoxy tri(ethylene glycol) amine, 2-hydroxypropyl amine and 3-(dimethylamino)-1-propylamine). Sequential aminolysis using Oregon Green cadaverine first followed by 2-hydroxypropyl amine enables …
Cationic copolymers of ?,?-poly-(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and ?,?-polyasparthylhydrazide (PAHy): synthesis and characterization
2000
In the present study the derivatization of two water-soluble synthetic polymers, α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and α,β-polyasparthylhydrazide (PAHy), with glycidyltrimethylammonium chloride (GTA) is described. This reaction permits the introduction of positive charges in the macromolecular chains of PHEA and PAHy in order to make easier the electrostatic interaction with DNA. Different parameters affect the reaction of derivatization, such as GTA concentration and reaction time. PHEA reacts partially and slowly with GTA; on the contrary the reaction of PAHy with GTA is more rapid and extensive. The derivatization of PHEA and PAHy with GTA is a convenient method to introdu…
Polymerization of long chain alkyl glycidyl ethers: a platform for micellar gels with tailor-made melting points
2018
Controlled polymerization of long-chain alkyl glycidyl ethers (AlkGE) under anionic ring opening polymerization conditions is enabled by the addition of a crown ether (18-crown-6, K+). Homopolymers with molecular weights in the range of 4000 to 9000 g mol−1 and side chain melting temperatures of 14 °C (C12-AlkGE) and 43 °C (C16-AlkGE), respectively were synthesized. Furthermore, a series of amphiphilic ABA polyether triblock copolymers with polyethylene glycol (PEG) as the hydrophilic central block (Mn = 6k, 10k, and 20k g mol−1) with total molecular weights in the range of 7000 to 28 000 g mol−1 and narrow dispersity (1.12 to 1.34) were prepared. Separate melting endotherms of the triblock…
One-step synthesis of multi-alkyne functional hyperbranched polyglycerols by copolymerization of glycidyl propargyl ether and glycidol
2013
By copolymerization of glycidol with the alkyne-containing oxirane monomer glycidyl propargyl ether (GPE), hyperbranched polyglycerol (hbPG) with a defined number of alkyne functionalities (up to 38%) can be obtained in a one-step procedure. The number of alkynes can be adjusted by the glycidol/GPE ratio to provide multi-alkyne functional hbPGs, maintaining the highly branched polyether structure. Interestingly, the acidic proton of the alkyne moiety does not interfere with the proton exchange mechanism during the polymerization of glycidol. By specific modification of the synthesis procedure, crosslinking reactions can be suppressed. The polymers exhibit molecular weights ranging from 1800…
Linear-Hyperbranched Graft-Copolymers via Grafting-to Strategy Based on Hyperbranched Dendron Analogues and Reactive Ester Polymers
2012
The synthesis of hyperbranched polyglycerol dendron analogues with precisely one focal amino functionality (H2N-hbPG) and their use for the synthesis of linear-hyperbranched graft-copolymers in a grafting-to approach is reported. By use of N,N-dibenzyl tris(hydroxylmethyl) aminomethane as a novel initiator for the ring-opening multibranching polymerization of glycidol, dendron analogues with one focal amino functionality of molecular weights ranging from 500 to 15000 g mol–1 and narrow to moderate polydispersities (Mw/Mn = 1.2–1.9) were synthesized, as confirmed by NMR and SEC. After removal of the benzyl protective groups, the accessibility and selective transformation of the focal amino g…
Molecular parameters of hyperbranched polymers made by self-condensing vinyl polymerization of macroinimers
2000
The molecular weight averages and the degree of branching, DB, of a hyperbranched polymer obtained by self-condensing vinyl polymerization (SCVP) of a macroinimer A-(m)γ-B* is calculated by modifying the existing equations for SCVP. The polydispersity is lowered by a factor (γ + 1), where γ is the degree of polymerization of the macroinimer. DB decreases with γ, however, at full conversion the DB of the polymacroinimer is approximately 60% higher than expected from the “dilution” of an AB* inimer with linear m units. This is the result of the existence of a new kind of branched units. The structure of polymacroinimers is similar to the pattern of a highly branched copolymer obtained by self…