Search results for "polymers"
showing 10 items of 3567 documents
Systematic Variation of the Degree of Branching (DB) of Polyglycerol via Oxyanionic Copolymerization of Glycidol with a Protected Glycidyl Ether and …
2017
Drug release from calcium and zinc pectinate beads: Impact of dissolution medium composition
2011
The aim of this study was to investigate drug release from calcium and zinc pectinate beads and to understand the impact of medium electrolytes during drug transfer. A potential drug carrier for colonic drug delivery (rutin) was prepared with calcium and zinc pectinate beads and was tested in three different simulated intestinal fluids (pH 7.3) with phosphates (Sorensen’s and Mc Ilvaine’s buffers) and without phosphates (Tris-buffer). According to swelling studies and zinc ions release, it was showed that zinc ions keep adhering to the bead surface. Drug release and swelling behaviour from the two dosage forms depend not only on pH and ionic strength but also on the electrolytes there were …
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-…