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- MALDI-TOF MS (4)
- MALDI (3)
- Polylactides (3)
- Ring-opening polymerization (3)
- Conductive carbon tape (2)
- Pollen (2)
- Sample pretreatment (2)
- Transesterification (2)
- Blockcopolymer (1)
- Catalysts (1)
- Cationization (1)
- Controlled radical polymerization (1)
- Cyclopolymerization (1)
- Dispersity (1)
- Equilibration (1)
- Hybrid nanoparticles (1)
- Iron oxide nanoparticles (1)
- Irreversible polycondensation (1)
- Lactides (1)
- Laser-induced redox reactions (1)
- MALDI TOF MS (1)
- Mass spectrometry (1)
- Morphology (1)
- Nanoparticles separation asymetrical flow field flow fractionation (1)
- Oligospiroketals (1)
- PCA (1)
- Polycaprolactone (1)
- Polyester (1)
- Polylactide (1)
- Polymer MALDI (1)
- Polymerization (1)
- Polystyrene (1)
- Principal component analysis (1)
- Ring-expansion polymerization (1)
- Sn catalysts (1)
- Sulfobetaines (1)
- Target plate material (1)
- Tin catalysts (1)
Five new catalysts are prepared from dibutyltin oxide and catechol (HCa),
2,3-dihydroxynaphthalene (NaCa), 4-tert-butyl catechol (BuCa), 4-cyano
catechol (CyCa), and 4-benzoyl catechol (BzCa), but only BuCa gives useful
results. When benzyl alcohol is used as an initiator, linear chains having
benzyl ester end groups are formed in a slow polymerization process. In
contrast to cyclic or noncyclic dibutyltin bisalkoxides, neat BuCa yields
cyclic poly(l-lactide)s via a fast ring-expansion polymerization. Under certain
conditions, a high-melting crystalline phase (Tm = 191 °C) is obtained.
At 160 °C and short reaction times even-numbered cycles are slightly
prevailing, but, surprisingly, at 120 °C, odd-numbered cycles are predominantly
formed. These results definitely prove that a ring-expansion mechanism
is operating.
The performance of a miniaturized channel for the separation of polymer and metal nanoparticles (NP) using Asymmetrical Flow Field-Flow Fractionation (AF4) was investigated and compared with a conventional AF4 system. To develop standard separation methods, experimental parameters like cross flow, gradient profile and injection time were varied and optimized.
Corresponding chromatographic parameters were calculated and compared. Our results indicate that the chromatographic resolution in the miniaturized channel is lower, whereas significantly shorter analyses time and less solvent consumption were obtained. Moreover, the limit of detection (LOD) and limit of quantification (LOQ) obtained from hyphenation with a UV-detector are obviously lower than in a conventional channel, which makes the miniaturized channel interesting for trace analysis.