Nowadays, amphiphilic molecules play an important role in our life. In medical applications, amphiphilic block copolymers have attracted much attention as excipients in drug delivery systems. Here, the polymers are used as emulsifi ers, micelles, or polymersomes with a hydrophilic corona block and a hydrophobic core or membrane. The aggregation behavior in aqueous solutions of a series of different amphiphilic block copolypeptoids comprising polysarcosine as a hydrophilic part is here reported. The formation of aggregates is investigated with 1 H NMR spectroscopy and dynamic light scattering, and the determination of the critical micelle concentration (cmc) is performed using pyrene fl uorescence spectroscopy. For the different block copolypeptoids cmc values ranging from 0.6 × 10 −6 M to 0.1 × 10 −3 M are found. The tendency to form micelles increases with increasing hydrophobicity at the nitrogen side chain in the hydrophobic moiety. Furthermore, in the case of the same hydrophobic side chain, a decreasing hydrophilic/lipophilic balance leads to the formation of larger aggregates. The aggregates formed in the buffer are able to solubilize the hydrophobic model compounds Reichardt's dye and pyrene, and exhibit versatile microenvironments. Final investigations about the cytotoxicity reveal that the block copolypeptoids are well tolerated by mammalian cells up to high concentrations.
Molecular brushes of poly(2-oxazoline)s (POx) are an intriguing class of polymers as they combine a unique architecture with the properties of POx as a biomaterial. Here, the synthesis of several POx macromonomers with methacrylate end groups and consecutive grafting through polymerization by aqueous atom transfer radical polymerization (ATRP) at room temperature is reported. 1 H-NMR spectroscopy and size exclusion chromatography (SEC) confirmed the synthesis of POx molecular brushes with maximum side chain grafting densities, narrow molar mass distributions (Ð ≤ 1.16) and final molar masses corresponding to the initial macromonomer : initiator ratio. Chain extension experiments show high end group fidelity, formation of block copolymer molecular brushes and kinetic studies revealed a polymerization behavior of oligo(2methyl-2-oxazoline methacrylate) very similar to the frequently used oligo(ethylene glycol) methacrylate (OEGMA 475 ). Aqueous solutions of POx molecular brushes with poly(2-ethyl-and 2-isopropyl-2-oxazoline) side chains exhibit the typically defined thermoresponsive behavior with a tunable, very narrow and reversible phase transition. P(MeOx 7 -MA) 52 0.118 P(MeOx 7 -MA) 104 0.116 P(MeOx 7 -MA) 202 0.114 P(MeOx 21 -MA) 50 0.146 P(MeOx 21 -MA) 91 0.153 P(EtOx 21 -MA) 50 0.149 P(EtOx 21 -MA) 92 0.156 P(EtOx 21 -MA) 183 0.153 Macromonomer synthesis Macromonomer MeOx 7 -MA: In a glove box, 5.7774 g (35.2 mmol, 1 eq) methyltriflate was dissolved in 45 mL acetonitrile and 14.9237 g (175.4 mmol, 5.0 eq) 2-methyl-2-oxazoline were added slowly at r.t.. The solution was stirred at 90 °C for 20 min. Afterwards the solution was
The influence of ambient laboratory light from common fluorescent lamps on AGET, ARGET, and classical ATRP reactions was investigated and significant differences were found except for ARGET ATRP.
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