TY  - JOUR
A1  - Kricheldorf, Hans R.
A1  - Weidner, Steffen
A1  - Scheliga, Felix
T1  - Polycondensation of L-lactic acid: a deeper look into solid state polycondensation
JF  - Polymer Chemistry
N2  - L-Lactic acid (LA) was condensed in the presence of SnCl2 or 4-toluenesulfonic acid (TSA) at 140 °C, and chain growth without cyclization was observed. In addition, poly(L-lactic acid)s (PLAs) with a degree of polymerization (DP) of 25, 50 or 100 were prepared by water-initiated ring-opening polymerization (ROP). These PLAs were annealed in the solid state at 140 °C and 160 °C in the presence of tin(II) 2-ethylhexanoate (SnOct2, SnCl2 or TSA). The changes in the molar mass distribution and in the topology were characterized by means of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and size exclusion chromatography (SEC). With increasing time, fewer side reactions caused higher molar masses and increasing fractions of cyclic polylactides (cPLA) were obtained. Their “saw tooth” pattern in the MALDI-TOF mass spectra indicated the formation of extended ring crystallites in the solid state. TSA was the most active catalyst and caused fewer side reactions than SnCl2, which was the least reactive catalyst. Acetylation of the CH-OH end groups hindered polycondensation and prevented the formation of cPLAs. Reaction mechanisms will be discussed.
KW  - MALDI-TOF MS
KW  - Polycondensation
KW  - Polylaktide
KW  - Solid state
PY  - 2025
UR  - https://nbn-resolving.org/urn:nbn:de:kobv:b43-625271
DO  - https://doi.org/10.1039/d4py01191k
SN  - 1759-9962
SP  - 1
EP  - 9
PB  - Royal Society of Chemistry (RSC)
AN  - OPUS4-62527
LA  - eng
AD  - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany
ER  -