Search results for "Copolymer"

Combining Ring-Opening Multibranching and RAFT Polymerization: Multifunctional Linear–Hyperbranched Block Copolymers via Hyperbranched Macro-Chain-Tr…

2013

The synthesis of a hyperbranched macro-chain-transfer agent for RAFT polymerization of functional methacrylate or methacrylamide monomers was achieved by selectively attaching one single CTA onto hyperbranched polyglycerol dendron analogues. The combination of ring-opening multibranching polymerization of glycidol and subsequent RAFT polymerization of the hyperbranched macro-chain-transfer agents created a new route to a variety of multifunctional linear–hyperbranched block topologies. All linear–hyperbranched block copolymers could be synthesized with controlled molecular weight (Mn = 3.2–43.7 kg/mol) and low polydispersity (PDI = 1.15–1.34). As first examples for this universal approach, …

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

2017

Synthesis and Sequential Deprotection of Triblock Copolypept(o)ides Using Orthogonal Protective Group Chemistry

2014

The synthesis of triblock copolymers based on polysarcosine, poly-N-ε-t-butyloxycarbonyl-l-lysine, and poly-N-ε-t-trifluoroacetyl-l-lysine by ring-opening polymerization of the corresponding α-amino acid N-carboxyanhydrides (NCAs) is described. For the synthesis of N-ε-t-butyloxycarbonyl-l-lysine (lysine(Boc)) NCAs, an acid-free method using trimethylsilylchloride/triethylamine as hydrochloric acid (HCl) scavengers is presented. This approach enables the synthesis of lysine(Boc) NCA of high purity (melting point 138.3 °C) in high yields. For triblock copolypept(o)ides, the degree of polymerization (Xn ) of the polysarcosine block is varied between 200 and 600; poly-N-ε-t-butyloxycarbonyl-l-…

Utilization of Poly(vinylchloride) and Poly(vinylidenefluoride) as Macroinitiators for ATRP Polymerization of Hydroxyethylmethacrylate. Electroanalyt…

2015

The utilization of poly(vinylchloride) (PVC) and poly(vinylidenefluoride) (PVDF) as macroinitiators for atom transfer radical polymerization (ATRP) of hydroxyethylmethacrylate (HEMA) was studied performing electroanalytical investigations and “grafting from” experiments in order to achieve information on the possibility of modifying such commercial polymers by this controlled free radical polymerization technique. This study was performed changing various operating parameters such as the nature of the copper salt, the ligand, the solvent, the temperature and the reaction time. Electroanalytical data suggest that PVC can be easily activated by both CuCl/ Tris(2-pyridylmethyl)amine (TPMA) and…

ABC triblock polyampholytes containing a neutral hydrophobic block, a polyacid and a polybase

1997

Well defined ABC triblock copolymers of polystyrene-block-poly(2-vinylpyridine)-block-poly(tert-butyl methacrylate) and polystyrene-block-poly(4-vinylpyridine)-block-poly(tert-butyl methacrylate) were synthesized by sequential living anionic polymerization in tetrahydrofuran. Triblock copolymers with narrow molecular weight distribution were obtained. Hydrolysis of the poly(tert-butyl methacrylate) block yields polystyrene-block-polyvinylpyridine-block-poly(methacrylic acid) which demonstrates pH-dependent solution properties. Interpolymer complexation of the polyvinylpyridine and poly(methacrylic acid) blocks in the micellar solution is studied in dependence of the pH in solution by potent…

Sequential conversion of orthogonally functionalized diblock copolymers based on pentafluorophenyl esters

2010

Statistic and block copolymers exhibiting activated ester side groups were synthesized by reversible addition-fragmentation chain transfer polymerization in the presence of cumyl dithiobenzoate, benzyl dithiobenzoate, and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid as chain transfer agents. Pentafluorophenyl methacrylate and pentafluorophenyl 4-vinylbenzoate were used to enable a sequential functionalization of the obtained copolymers by conversion of the activated esters with different amines. 1H NMR spectroscopy, 19F NMR spectroscopy, and FTIR spectroscopy showed the successful step-by-step conversion of the different activated esters by aniline followed by aliphatic amines, thereby r…

Size Tunable Core Crosslinked Micelles from HPMA-Based Amphiphilic Block Copolymers

2017

A variety of core crosslinkable hydroxypropylmethacrylamide-based block copolymers are synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, which are composed of hydroxypropyl-methacrylate as hydrophilic block combined with a statistical hydrophobic block from laurylmethacrylate and the photo crosslinkable monomer. It is discovered that the self-assembled micellar aggregates from these systems vary strongly in size depending not only on the velocity of the polarity switch (nanoprecipitation or slow dialysis) but also on the solvent from which they were dialyzed. In this way micellar aggregates with an Rh varying between 15 and 80 nm can be prepared from the…

Inimer-Promoted Synthesis of Branched and Hyperbranched Polylactide Copolymers

2009

A series of (hyper)branched poly(l-lactide)(PLLA) copolymers has been prepared by ring-opening multibranching copolymerization of l-lactide with a hydroxyl-functional (ABB′) lactone inimer, 5HDON (5-hydroxymethyl-1,4-dioxane-2-on). Polymerization was conducted in bulk and solution and catalyzed either by stanneous-2-ethyl hexanoate (Sn(Oct)2) or an organic base, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Precise structural characterization of the resulting branched copolyester structures was accomplished by a combination of 2D NMR techniques, relying on the comparison with model compounds. The 5HDON inimer was employed in 1% to 20% fractions and is incorporated either as a dendritic unit or…

in vitro biological evaluation of folate-functionalized block copolymer micelles for selective anti-cancer drug delivery.

2008

The main objective of this study was to evaluate the ability of folic acid-functionalized diblock copolymer micelles to improve the delivery and uptake of two poorly water-soluble anti-tumor drugs, tamoxifen and paclitaxel, to cancer cells through folate receptor targeting. The diblock copolymer used in this study comprised a hydrophilic poly[2-(methacryloyloxy)ethyl phosphorylcholine] (MPC) block, carrying at the chain end the folate targeting moiety, and a pH-sensitive hydrophobic poly[2-(diisopropylamino)ethyl methacrylate] (DPA) block (FA-MPC-DPA). The drug-loading capacities of tamoxifen- and paclitaxel-loaded micelles were determined by high performance liquid chromatography and the m…

BIOADHESIVE PROPERTIES OF A POLYAMINOACIDIC HYDROGEL: EVALUATION BY ATR FT-IR SPECTROSCOPY

2005

The bioadhesive properties of a novel chemical hydrogel based on a polymer of protein-like structure, have been investigated by using ATR FT-IR spectroscopy. In particular, the copolymer PHG obtained by partial derivatization of PHEA with GMA was chemically crosslinked by UV irradiation at 313 nm. Crosslinked PHG was treated with water to obtain a swelled sample, named PHG-UV gel, that was brought into contact with a phosphate buffer/citric acid solution at pH 7.0 in the absence or in the presence of mucin at various concentrations (0.01, 0.1 and 1 wt.-%). Preliminary dynamic swelling studies have evidenced the occurrence of an interaction between the PHG-UV gel and the glycoprotein. This r…