Polylactones, 22 ABA triblock copolymers of <scp>L</scp>‐lactide and poly(ethylene glycol)

Kricheldorf, Hans R.; Meier‐Haack, Jochen

doi:10.1002/macp.1993.021940229

Cited by 165 publications

(100 citation statements)

References 7 publications

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“…It was found that all CH 2 OH end groups of PEO are esterified with IBMD units using the trifluoroacetic anhydride (TFAA) method 21) . TFAA causes rapid esterification of OH end-groups, and the neighbouring CH 2 protons experience a downfield shift of about 0.6 0.1 ppm.…”

Section: Synthesis and Characterization Of Pibmd-b-peo-b-pibmdmentioning

confidence: 99%

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

Feng

Klee

Höcker³

1999

Macromol. Chem. Phys.

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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.

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Section: Synthesis and Characterization Of Pibmd-b-peo-b-pibmdmentioning

confidence: 99%

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

Feng

Klee

Höcker³

1999

Macromol. Chem. Phys.

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“…The syntheobtain poly ( 1-caprolactone ) -poly ( ethylene glysis of polyester-polyether type block copolymer col ) -poly ( 1-caprolactone ) triblock copolymer has attracted much attention. [1][2][3][4] Recently, it was ( PECL ) . reported that the synthesis of ABA type block copolymers comprising poly(L-lactide) (A) and poly-(ethylene glycol) (B) segments obtained via an-…”

Section: Introductionmentioning

confidence: 97%

Synthesis and characterization of poly(?-caprolactone)-poly(ethylene glycol) block copolymer

Zhu

Xiong

Zhang

et al. 1997

J. Polym. Sci. A Polym. Chem.

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Poly(ϵ‐caprolactone)–poly(ethylene glycol)–poly(ϵ‐caprolactone) triblock copolymers (PECL) covering a wide range of poly(ethylene glycol) (PEG) lengths were synthesized with alkali metal alkoxide derivatives of poly(ethylene glycol). The effects of various factors, such as amount of the initiator, reaction time and temperature, polarity of solvent, length of PEG segment, and counterion on the polymerization were investigated. The copolymers were characterized by 1H‐NMR, IR, GPC, and DSC. It was found that THF system is superior to toluene system. The conversion of the monomer increased with increase of the initiator concentration. High molecular weight of the copolymer and high conversion of the monomer was obtained at below 30°C within 5 min. The polymerization process was studied by GPC and the coexistence of propagation and transesterification reaction was found, which leaded to relatively broad molecular weight distribution of the copolymers. © 1997 John Wiley & Sons, Inc.

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“…Besides environmental conditions, such as temperature, the degradation rate is strongly dependent on the film thickness, 1 additives such as monomer, 2 basic compounds, 3 acid drugs 4 or superoxide ion, 5 and catalyst such as SnOct 2 or zinc metal, [6][7][8][9] etc. The molecular architecture, [10][11][12][13] hydrophilicity, [14][15][16] reasonable crosslink, 17,18 and surface modification 19,20 have vital influence on the degradation properties, too.…”

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confidence: 99%

Synthesis, Characterization, and Degradation Behaviors of End-Group-Functionalized Poly(trimethylene carbonate)s

Zhuo

2003

Polym J

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KEY WORDSPolycarbonate / Biodegradable Material / End-Group Effect / Biodegradable polymers are under investigation for biomedical, pharmaceutical applications, etc. Degradability is one of their important characters. Many factors affect the degradation rate. Besides environmental conditions, such as temperature, the degradation rate is strongly dependent on the film thickness, 1 additives such as monomer, 2 basic compounds, 3 acid drugs 4 or superoxide ion, 5 and catalyst such as SnOct 2 or zinc metal, 6-9 etc. The molecular architecture, 10-13 hydrophilicity, 14-16 reasonable crosslink, 17,18 and surface modification 19,20 have vital influence on the degradation properties, too.End-group effect is demonstrable on the degradation rate. 21 It was shown that poly(lactide-co-glicolide) (PLGA) with a free carboxyl group at the polymer terminus (uncapped PLGA) degrades faster than PLGA with a hydrophobic alkyl ester linkage at the polymer terminus (capped PLGA). 22 Lee 21 synthesized various end-group-functionalized, such as OH-, NH 2 -, Cl-, or COOH-terminated polylactides (PLAs) and found that the COOH end group plays a crucial role in the hydrolysis degradation in both alkaline and acidic medium. Protection of OH end group results in a substantial retarded degradation. 23 Polyanhydrides capped with fatty terminals also show a significantly slow degradation and drug release rate. 24 Linear aliphatic polycarbonates, such as poly(1,3-trimethylene carbonate) (PTMC), have been shown to be potential for use as medical implants and for drugdelivery applications. 25 But they degrade unexpectedly slow. 10 Many efforts have been made to enhance their degradation rate. Copolymers of PTMC were synthesized for adapting to applications requiring different degradation rates and mechanical properties. 10,[26][27][28][29] Pendant hydroxyl groups have been introduced to improve the hydrophilicity and hence the degradability. 30 Since end groups have special effect on degradation rate, end-group functionalized polycarbonates will have different degradation rate. Because the polymers of multiarm architecture have a higher end-group concentration than linear polymers of the same molecular weights, the multiarm structure can strengthen the end group effect. Some researchers have synthesized the OH-terminated PTMC by ring-opening polymerization (ROP), but the degradability has not been involved up to now. 31 In the present study, we synthesize PTMC with different number of arms terminated by hydroxyl group or carboxylic group and study the degradability of such end-group-functionalized PTMCs preliminarily. EXPERIMENTAL 1,3-Trimethylene carbonate (TMC) was synthesized according to the reported method. 32 All other regents were treated just before use. Synthesis of OH-Terminated PTMC (OH-PTMC)The ring-opening polymerizations (ROP) of TMC initiated by alcohols are illustrated in Scheme 1. These polymerization reactions were carried out in the melt bulk. All reaction reagents were used just after treated. A known amount of TMC was charged ...

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Polylactones, 22 ABA triblock copolymers of L‐lactide and poly(ethylene glycol)

Cited by 165 publications

References 7 publications

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

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

Synthesis and characterization of poly(?-caprolactone)-poly(ethylene glycol) block copolymer

Synthesis, Characterization, and Degradation Behaviors of End-Group-Functionalized Poly(trimethylene carbonate)s

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