Synthesis and characterization of new ABA triblock copolymers with poly[3(S)-isobutylmorpholine-2,5-dione] and poly(ethylene oxide) blocks

Abstract

SUMMARY: ABA type block copolymers with poly[3(S)-isobutylmorpholine-2,5-dione] (PIBMD, A) and poly(ethylene oxide) (M -n = 6 000, PEO, B) blocks, PIBMD-b-PEO-b-PIBMD, were synthesized via ringopening polymerization of 3(S)-isobutylmorpholine-2,5-dione in the presence of hydroxytelechelic poly-(ethylene oxide) with stannous octoate as a catalyst. M -n of the resulting copolymers increases with increasing 3(S)-isobutylmorpholine-2,5-dione content in the feed at constant mole ratio of monomer (M) to catalyst (C) (M/C = 125). No racemization of the leucine residue takes place during both homopolymerization of IBMD and polymerization of IBMD in the presence of PEO and Sn(Oct) 2 . The melting temperature of the PIBMD segments in the block copolymers depends on the length of the PIBMD blocks. The melting temperature of the PEO blocks is lower than that of the homopolymer, and the crystallinity of the PEO block decreases with increasing length of the PIBMD blocks. The PIBMD block crystallizes first upon cooling from the melt. This leads to only imperfect crystallization or no crystallization of the PEO blocks.

Calcium Alcoholates of Hydroxytelechelic Poly(ethylene oxide)s as Initiators for the Ring-Opening Polymerization of 3-(S)-Isopropylmorpholine-2,5-dione

“…[25] In the polymerization of 3-(S)-isobutylmorpholine-2,5-dione in the presence of PEO and Sn(oct) 2 , racemization of the l-leucine residue does not occur either. [19,20] The intensity of the resonance at d = 4.62 ppm observed in the 1 H NMR spectrum of 4 is stronger than of that in the spectrum of 3, which indicates that racemization is more pronounced in 4 than in 3. The racemization of the l-valine residue during copolymerization of IPMD with PEO in the presence of CaH 2 was determined from 1 H NMR spectra and is listed in Table 1.…”

“…[19,28] The 19 F NMR spectrum of the block copolymer treated with TFAA shows only one peak at d = -75.78 ppm. It is noted that a resonance at -75.35 ppm, which would be due to PEO treated with TFAA, is absent.…”

Expected and unexpected reactions in ring-opening (co)polymerization

“…[46] Using hydroxytelechelic ethylene oxide as the macroinitiator in combination with tin octoate as the catalyst an A-B-A triblock copolymer 88 with polydepsipeptide side blocks and a polyethylene oxide middle block was obtained. [47,48] The goal of our further investigation was to prepare poly(ester-amide)s based an b-hydroxy-acids and a-or eaminoacids. For the preparation of cyclic ester amide monomers 91 an alternative route was applied based on the ring-expansion reaction of N-(hydroxy-acyl)-amides 89 [49] (Eq.…”

Synthesis of Functional Polydepsipeptides via Direct Ring‐Opening Polymerization and Post‐Polymerization Modification

“…[1] The most convenient synthetic route for the preparation of polydepsipeptides is the ring-opening polymerization of the corresponding morpholine-2,5-diones. [2][3][4][5][6][7][8][9][10][11][12][13][14] The ringopening polymerization of morpholine-2,5-diones can be performed using both organometallic (typically tin(II)2-ethylhexanoate (Sn(Oct) 2 )) [2,4,6,15] as well as enzymatic catalysis. [9,10] Jörres et al, for example, have reported the preparation of polydepsipeptides based on (3S,6S)-3-isopropyl-6-methylmorpholine-2,5-dione with number-average molecular weights of up to 20 000 g Á mol À1 .…”