Search results for "Radical polymerization"
showing 10 items of 184 documents
Cyclodextrins in polymer synthesis: Free radical polymerization of methylated β-cyclodextrin complexes of methyl methacrylate and styrene, controlled…
2000
Methylated β-cyclodextrin (me-β-CD) was used to complex the hydrophobic monomers methyl methacrylate (1) or styrene (2) yielding the water-soluble 1 : 1-host/guest complexes methyl methacrylate/me-β-CD (1 a) and styrene/me-β-CD (2 a), respectively. In addition, the hydrophobic chain-transfer agent dodecanethiol (3) was complexed by two equivalents of me-β-CD yielding the water-soluble dodecanethiol/me-β-CD (3 a). The included monomers were polymerized in water by a free-radical mechanism in the presence of 3 a as the chain-transfer agent. The chain-transfer constants were determined. In order to evaluate these results, the chain-transfer constants of 3 were also determined in the case of th…
Cyclodextrins in Polymer Synthesis: Synthesis and Influence of Methylatedβ-Cyclodextrin on the Radical Polymerization Behavior of 1,1-Disubstituted 2…
2001
The chemical and enzymatic hydrolyses of 1,1-diethoxycarbonyl-2-vinylcyclopropane (1) were investigated. The product of the pig liver esterase (PLE)-catalyzed hydrolysis of 1 is a chiral trans monoester of 2-vinylcyclopropane dicarboxylic acid. New 1,1-disubstituted 2-vinylcyclopropane monomers (2a, b) were synthesized by the esterification of this ester. Methylated β-cyclodextrin was used to complex monomers 2a, b, yielding water-soluble 1 : 1 host/guest complexes. These complexes were polymerized in aqueous media by a free-radical ring-opening mechanism.
New Perspectives of HPMA-based Copolymers Derived by Post-Polymerization Modification
2014
Poly[N-(2-hydroxypropyl) methacrylamide] (HPMA) was one of the first polymers applied as polymer drug conjugate in the clinics. Since then many attempts have been made to expand the functionality of HPMA-based copolymers from advanced synthetic pathways to multiple biomedical applications. This Feature Article highlights multifunctional HPMA based copolymers prepared by controlled radical polymerization and subsequent post-polymerization modification of activated ester precursor polymers via aminolysis. This approach combines precise control of the polymer's microstructure (molecular weight, dispersity, block copolymer formation, end group functionalization) with an easy introduction of var…
Comparison of living polymerization systems
1994
Recent developments in the field of living polymerization are surveyed. Comparison of the available mechanistic and kinetic information is made for living anionic, cationic, free radical, group transfer, ring-opening metathesis, Ziegler-Natta and immortal polymerizations. This evaluation indicates that the majority of living polymerizations involve quasiliving equilibrium between active (propagating) and dormant (nonpropagating) polymer chains. On the basis of the kinetics of a general model for quasiliving and ideal living polymerizations it is concluded that ideal living polymerization is a special subclass of quasiliving polymerizations. Classification of living polymerization systems is…
Combining oxyanionic polymerization and click-chemistry: a general strategy for the synthesis of polyether polyol macromonomers
2014
We describe a synthetic pathway to tailor-made amphiphilic macromonomers by a combination of anionic ring-opening polymerization and copper-catalyzed azide–alkyne cycloaddition (CuAAC). Linear polyglycerol and poly(glyceryl glycerol) were synthesized in a controlled manner by anionic ring-opening polymerization of ethoxyethyl glycidyl ether or isopropylidene glyceryl glycidyl ether, respectively, with narrow and monomodal molecular weight distributions (Mw/Mn < 1.20) and molecular weights ranging from 850 g mol−1 to 2500 g mol−1. After end-capping with propargyl bromide and removal of the protecting groups, the hydrophilic precursors were quantitatively clicked to a series of hydrophobic az…
RAFT polymerization of activated 4-vinylbenzoates
2009
The reversible addition fragmentation chain transfer (RAFT) polymerization of five active ester monomers based on 4-vinylbenzoic acid had been investigated. Pentafluorophenyl 4-vinylbenzoate could be polymerized under RAFT conditions yielding polymers with very good control over molecular weight and narrow molecular weight distributions. Following the synthesis of diblock copolymers consisting of polystyrene, polypentafluorostyrene, poly(4-octylstyrene), or poly(4-acetoxystyrene) as an inert block and poly(pentafluorophenyl 4-vinylbenzoate) as a reactive block was successfully performed. The diblock copolymer poly(pentafluoro styrene)-block-poly(pentafluorophenyl 4-vinylbenzoate) had been a…
Polymeric nitrones, 1. Synthesis and modification of polymeric nitrones derived from polymerizable aldehydes
1999
The model compound N,C-diphenylnitrone[N-(benzylidene)aniline-N-oxide] (3) was prepared by condensation of benzaldehyde with phenylhydroxylamine to study its thermal stability. X-ray diffraction analysis of a single crystal established the conformation of the nitrone group. A new monomer 4-(methacryloyloxy)benzaldehyde-phenylnitrone (8) was also prepared and could not be polymerized with 2,2′-azobisisobutyronitrile (AIBN) as initiator at 70°C. Under these conditions the nitrone reacted exclusively in an intermolecular 1,3-dipolar cycloaddition to give oligomeric tetrahydro-1,2-oxazoline derivates. The kinetics of the cycloaddition was investigated. Additionally, different (meth)acryl- and s…
Synthesis and polymerization of active ester monomers based on 4-vinylbenzoic acid
2007
Abstract Nine active ester monomers based on 4-vinylbenzoic acid have been synthesized. Under free radical polymerization conditions these monomers could successfully be polymerized yielding reactive polymers with molecular weights of around M n = 20.000–50.000 g/mol and molecular weight distributions M w / M n of around or below 2 in good yields. Polymer analogous reactions with amines have been investigated by time-resolved FT-IR spectroscopy and it was found that especially poly(pentafluorophenyl 4-vinylbenzoate) featured a significant reactivity, such that polymer analogous reactions proceeded quantitatively with amines within less than 5 min at 0 °C.
Molecular Parameters of Hyperbranched Copolymers Obtained by Self-Condensing Vinyl Copolymerization, 2. Non-Equal Rate Constants
2001
The kinetics, molecular weight averages, and the average degree of branching, DB, are calculated for the self-condensing vinyl copolymerization (SCVCP) of a vinyl monomer M with an "inimer" AB* in the case of different reactivities of active species. Emphasis is given to two limiting cases: formation of "macroinimers" occurs if the monomer M is more reactive than the vinyl groups of inimers or polymer, and "hyperstars" are formed in the opposite case. It is shown that the kinetics, the molecular weight averages, and the average degree of branching strongly depend on the relative reactivities of monomer and inimer. Comparison with experimental data shows that consistent fits of the reactivit…
Poly(4-vinylbenzoyl azide): A New Isocyanato Group Generating Polymer
2007
4-Vinylbenzoyl azide was synthesized from p-vinylbenzoic acid and polymerized by free radical polymerization. The obtained polymer contained acyl azide groups which were thermally transformed to the corresponding isocyanato groups. Reactions on these polymers with ethanol, hydroxyethyl methacrylate and 1-pyrene-butanol proceeded quantitatively. Time-resolved FT-IR studies of the reactions with ethanol were carried out by varying the concentration and temperature. The effect of the solvent polarity on the Curtius rearrangement was investigated.