Synthesis of star-shapee poly(epsilon-caprolactone)-b-poly(DL-lactic acid-alt-glycolic acid) with multifunctional initiator and stannous octoate catalyst

Citation
Cm. Dong et al., Synthesis of star-shapee poly(epsilon-caprolactone)-b-poly(DL-lactic acid-alt-glycolic acid) with multifunctional initiator and stannous octoate catalyst, MACROMOLEC, 34(14), 2001, pp. 4691-4696
Citations number
45
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
MACROMOLECULES
ISSN journal
00249297 → ACNP
Volume
34
Issue
14
Year of publication
2001
Pages
4691 - 4696
Database
ISI
SICI code
0024-9297(20010703)34:14<4691:SOSPA>2.0.ZU;2-L
Abstract
Two types of three-arm or four-arm star-shaped hydroxy-terminated poly(epsi lon -caprolactone) (PCL) were successfully synthesized via the ring-opening polymerization of epsilon -caprolactone (CL) with multifunctional initiato r, such as trimethylolpropane (TMP) or pentaerythritol (PTOL), and stannous octoate (SnOct(2)) catalyst in bulk at 110 degreesC. The number-average mo lecular weight of PCL is proportional to the molar ratio of monomer to init iator. H-1 NMR spectroscopy of the resulting PCL indicates that it contains a primary hydroxy end group in each arm. The star-shaped PCL with hydroxy end groups can be used as a macroinitiator for block copolymerization with DL-3-methylglycolide (MG) using SnOct(2) catalyst in bulk at 115 degreesC. H-1 NMR spectra of the resulting block copolymers show that the molecular w eights and the unit compositions of the block copolymers were controlled by the molar ratios of MC monomer to hydroxy groups of PCL and MG to CL in fe ed, respectively. Moreover, the molecular weights of the resulting block co polymers linearly increased with the increase of the molar ratios of MG to CL in feed. The molecular weight distributions of the block copolymers were rather narrow (M-w/M-n = 1.09-1.26). C-13 NMR spectra of the resulting blo ck copolymers clearly show their diblock structures, that is, PCL as the fi rst block and poly(DL-lactic acid-ail-glycolic acid) (DL-PLGA50) with alter nating structures of lactyl and glycolyl units as the second block. Therefo re, two types of three-arm or four-arm star-shaped diblock copolyesters com prising the first block PCL and the second block DL-PLGA50 were successfull y synthesized via the sequential ring-opening polymerization of CL with mul tifunctional initiator and SnOct(2) catalyst and then followed by copolymer ization with MG.