Search results for "End-group"
showing 10 items of 93 documents
New folate-functionalized biocompatible block copolymer micelles as potential anti-cancer drug delivery systems
2006
Abstract The main objective of this study was to synthesize novel folic acid-functionalized diblock copolymer micelles and evaluate their solubilization of two poorly water-soluble anti-tumor drugs, tamoxifen and paclitaxel, which suffer from low water solubility and/or poor hydrolytic stability. The diblock copolymer consisted of a permanently hydrophilic block comprising 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) residues and a pH-sensitive hydrophobic block comprising 2-(diisopropylamino)ethyl methacrylate (DPA) residues. Folic acid (FA) was conjugated to the end of the MPC block so that this group was located on the micelle periphery. Tamoxifen- and paclitaxel-loaded micelles were…
Darstellung einer homologen Reihe von oligoallylalkoholen mit 1-cyano-1-methylethyl-endgruppen. Beispiel einer mehrfachen matrizenreaktion und einer …
1984
Reduction and hydrolysis of the ladder oligomers 1, 2, 3, 4, and 5 prepared from the acrylates of oligo (hydroxyphenylene-methylene)s was found to lead to a homologous series of oligo (allylalcohol)s (6a, 7a, 8a, 9a and10a) with good yields. These alcohols were characterized by analytical and spectroscopic methods. The reaction sequences, starting with the esterification of the oligo[(hydroxyphenylene) methylene]s 11a – 11e with acryloyl chloride followed by the formation of the ladder oligomers and ending with their reduction and hydrolysis into the oligo(allyl alcohol)s and the starting compounds 11a – 11e, represent a simple matrix reaction. A mixture of multiple acrylates was also subje…
Rapid Access to Polyfunctional Lipids with Complex Architecture via Oxyanionic Ring-Opening Polymerization
2011
Polymer-coated liposomes, particularly poly(ethylene glycol) (PEG)-substituted liposomes, have emerged as long-circulating carrier systems for drug delivery and diagnostic purposes. A rapid synthesis of three different types of multifunctional lipids with structurally diverse hydrophilic, polyether-based architectures via one- or two-pot approaches is described. Architectural variation is achieved by the combination of different oxyanionic polymerization strategies and various glycidyl ether building units. Branched polyglycerol lipids have been prepared via cholesterol- or 1,2-bis-n-alkyl glyceryl ether-initiated, oxyanionic ring-opening polymerization (ROP) of protected glycidyl ethers an…
Novel Multifunctional Polymeric Photoinitiators and Photo-Coinitiators Derived from Hyperbranched Polyglycerol
2007
A new class of hyperbranched PPIs and PPCs have been prepared. The introduction of compatibilizing groups such as MEEA or trimethylacetate enhanced their solubility in radiation-curable formulations and led to an improved photoactivity compared with the corresponding MPI and MPC. Although the molecular weights of the subject PPIs and PPCs exceeded 800 g mol -1 , the viscosities of the radiation-curable formulations were still suitable for inkjet application. The combination of high photoactivity, low viscosity, and low extract-ability after curing rendered the resulting hyperbranched PPIs and PPCs attractive as components in the inkjet ink for inkjet printing, e.g., in food packaging.
Novel Alkylanthracenes Synthesis, Reductive Alkylation, and Reductive Polymerization
1988
A series of novel substituted anthracenes has been prepared which carry two or four n-alkyl groups at C-2 and C-3 (C-6 and C-7). The route taken includes the synthesis of novel 2,3-dialkylbutadienes, their Diels-Alder reaction with 1,4-benzo- or 1,4-naphthoquinone, the dehydrogenation of the adducts, and the reduction of the anthraquinones. The substituted anthracenes are submitted to reduction and reductive alkylation in ethereal solvents and in liquid ammonia to yield 9,10-dialkyl-substituted 9,10-dihydroanthracenes. A modification of the reductive alkylation, i.e. the introduction of 1,n-dihaloalkanes as electrophiles, provides polymeric chains, in which dihydroanthracene moieties are li…
Synthesis of Linear and Star-Shaped Block Copolymers of Isobutylene and Methacrylates by Combination of Living Cationic and Anionic Polymerizations
1998
A new synthetic route for the preparation of polyisobutylene (PIB)-based linear and star-shaped block copolymers was developed by combining living carbocationic and anionic polymerizations. Living PIB chains were quantitatively endcapped with 1,1-diphenylethylene, leading to 1,1-diphenyl-1-methoxy (DPOMe) or 2,2-diphenylvinyl (DPV) termini, or both. Both the DPOMe- and DPV-terminated PIBs, and the mixtures of both endgroups were quantitatively metalated with K/Na alloy, Cs metal, or Li dispersion in THF at room temperature. The resulting stable macrocarbanion obtained by metalation with K/Na alloy was used to initiate living anionic polymerization of tert-butyl methacrylate (tBMA) yielding …
Synthesis of linear and three-arm star tert-chlorine-telechelic polyisobutylenes by a two-step conventional laboratory process
1997
A two-step conventional laboratory process was developed for the synthesis of mono- and difunctional linear and three-arm star tert-chlorine-telechelic polyisobutylenes (PIB) with desired molecular weights (MW) and narrow molecular weight distribution (MWD) by living carbocationic polymerization (LCCP). This polymerization method applies easy to handle operations and chemicals. LCCP of isobutylene (IB), was carried out in CH2Cl2 as solvent and with BCl3 as coinitiator in the first step to obtain soluble low MW PIB prepolymer with narrow MWD. This was followed by addition of hexane, TiCl4 and additional monomer in the second step to prepare PIBs with desired MW and narrow MWD in practically …
Solid-state polymerization of oxetanes. II. Investigation of the growth of the polymer phase as related to the mechanism of polymerization
1973
The radiation-induced solid-state polymerization of 3,3-bischloromethyloxetane (BCMO) was investigated by direct observation of the development of the morphology of the growing polymer phase in single crystals of the monomer. Electron microscopy shows that the polymerization gives rise to amorphous polymer in the first step. The polymer forms irregular platelets which aggregate into larger units without reflecting the crystalline order of the monomer. Subsequent to polymerization, the amorphous polymer crystallizes to the β-modification of poly-BCMO. If the partially polymerized crystals are extracted by solvents of the monomer, crystallization of the polymer is enhanced, and morphological …
What Limits the Molecular Weight and Controlled Synthesis of Poly(3-alkyltellurophene)s?
2016
Polytellurophenes are an emerging class of conjugated polymers; however, their controlled polymerization leading to high molecular weight materials has been a major challenge. Here we present a systematic investigation of the synthesis of poly(3-alkyltellurophene)s using the catalyst transfer polycondensation methodology. Learning that previous syntheses were limited by both polymerization reaction kinetics and polymer solubility, we design new tellurophene monomers to overcome these limitations. Controlled polymerization behavior up to Mn = 25 kDa, chain extension, block copolymerization, external initiation, and well-defined end groups are demonstrated for poly(3-alkyltellurophene)s with …
Branched and Functionalized Polybutadienes by a Facile Two-Step Synthesis
2008
Anionic polymerization was used to prepare silane-endfunctionalized polybutadiene macromonomers with different molecular weights ranging from 9 000 to 34000 g .mol- 1 . These were polymerized by a hydrosilylation reaction in bulk to obtain branched polymers, using Karstedt's catalyst. Surprisingly, the addition of monofunctional silanes during the polymerization showed only a minimal effect concerning the degree of polymerization. Furthermore, it was possible to introduce a variety of functional silanes without increasing the overall number of reaction steps by a convenient AB 2 + A type "pseudocopolymerization" method. All branched polymers were analyzed by SEC, SEC-MALLS, SEC-viscosimetry…