Synthesis and characterization of novel ABA triblock copolymers from L-lactide, glycolide, and PEG

Mohammadi-Rovshandeh, Jamshid; Farnia, S. Morteza F.; Sarbolouki, M. N.

doi:10.1002/(sici)1097-4628(19991121)74:8<2004::aid-app15>3.3.co;2-v

Cited by 4 publications

(6 citation statements)

References 12 publications

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“…Triblock copolymers with the general structure LA m EO n LA m were obtained by ring-opening polymerization of dl -lactide with PEG as initiator and stannous octoate as catalyst. The use of PEG diol results in an ABA-type triblock copolymer . The degree of polymerization of the LA is dependent on the feed ratio of lactide over PEG and was characterized by 1 H NMR.…”

Section: Resultsmentioning

confidence: 99%

“…Synthesis of the LA m EO n LA m Surfactants. The synthetic scheme for the triblock copolymers of poly(lactide)−poly(ethylene oxide)−poly(lactide) (LA m EO n LA m ) is illustrated in Figure , and it is similar to a previously published procedure . An appropriate amount of PEG, dl -lactide, and stannous octoate were charged into a 25 mL round-bottomed flask under the protection of nitrogen.…”

Section: Methodsmentioning

confidence: 99%

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Biocompatible and Biodegradable Copolymer Stabilizers for Hydrofluoroalkane Dispersions: A Colloidal Probe Microscopy Investigation

and

Rocha

2007

Langmuir

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In this work we investigate the ability of biodegradable and biocompatible lactide-based nonionic amphiphiles to stabilize a model drug (salbutamol base) dispersion in hydrofluoroalkane (HFA) propellant. A series of triblock copolymers of the type poly(lactide)-poly(ethylene glycol)-poly(lactide) (LA(m)EO(n)LA(m)) with varying molecular weight (MW) and % EO were synthesized. The cohesive forces between drug particles in liquid HFA in the presence of the amphiphiles were quantitatively determined by colloidal probe microscopy (CPM). The effect of cosolvent, oleic acid, and a nonionic triblock copolymer with the propylene oxide moiety as the HFA-phile was also investigated. CPM results show that the overall concentration, MW, surfactant tail (LA) length, and the ratio between the stabilizing LA moiety and the anchor EO group have a great impact on the drug cohesive forces. The CPM results in liquid HFA were correlated to the bulk physical stability of the drug suspensions in the propellant 1,1,1,2,3,3,3-heptafluoropropane (HFA227). The dispersions in HFA227 were significantly improved in the presence of LA(m)EO(n)LA(m), correlating well with the low cohesive forces determined by CPM. The applicability of LA-based amphiphiles might be extended to other suspension-based formulations provided a suitable headgroup is found. This study is relevant for the development of HFA-based dispersion pressurized metered-dose inhaler formulations.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Biocompatible and Biodegradable Copolymer Stabilizers for Hydrofluoroalkane Dispersions: A Colloidal Probe Microscopy Investigation

and

Rocha

2007

Langmuir

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“…The 1 H‐NMR peaks at δ H = 1.5, 3.6, 4.8, and 5.2 ppm are assigned to the methyl hydrogen of the LA, methylene hydrogen of the PEG1000, methylene hydrogen of the glycolide units, and methine hydrogen of the LA units. This demonstrates that the terminal hydroxy polyester PLGA‐PEG‐PLGA was synthesized through a hydroxyl‐bearing species initiating the lactone polymerization . The number average molecule weight (Mn) of PLGA‐PEG‐PLGA triblock copolymer determined by the peaks of δ H = 1.5, 3.6, and 4.8 ppm is 1900.…”

Section: Resultsmentioning

confidence: 99%

Fluorescently labeled degradable thermoplastic polyurethane elastomers: Visual evaluation for the degradation behavior

Liu

Shi

et al. 2015

J of Applied Polymer Sci

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Thermoplastic polyurethane elastomers (TPU) were synthesized with isophorone diisocyanate (IPDI) as the rigid segment, poly(lactic-co-glycolic acid) (PLGA-PEG-PLGA) diol as soft segment, and 1,4-butanediol (BDO) as the chain extender. During the chain extension process, three kinds of fluorescent monomers 4-(2-hydroxyethylamino)21,8-naphthoyl-(2-hydroxyethyl)imide (HNHI), 1,5-dihydroxy naphthalene (DHN), and dicoumarin (DIC) were introduced to get the fluorescently labeled degradable TPUs. The structure and degradation properties of the TPUs were characterized in detail. The results showed that there was no significant effect found on average molecular weight, mechanical properties, and glass transition temperature of polyurethane by introducing 0.001% (wt) weight percent of fluorescence monomers. The degradation behavior of fluorescent-tagged thermoplastic elastomer has been characterized with fluorescence microscopy. Results showed that polyurethane elastomers, in which fluorescence monomers especially HNHI were introduced by chemical reaction, had more homogeneous and stable fluorescence intensity than that with fluorescence monomers introduced by post blending. This work also provides a promising visual characterization approach to monitor degradation behavior of degradable TPUs for tissue engineering applications or drug delivery system.

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“…Much effort has been taken to improve the thermal and mechanical properties of PLLA, such as polymer blending or compounding with inorganic fillers. [4][5][6] Ikada et al 7 reported an interesting approach to improve the thermal properties of PLLA by blending PLLA with poly(D-lactic acid) (PDLA). After that, this phenomenon was verified by other researchers and the reason was attributed to the formation of PLA stereocomplex crystallites (PLA SC).…”

Section: Introductionmentioning

confidence: 99%

Improved expansion ratio and heat resistance of microcellular poly(L-lactide) foam via in-situ formation of stereocomplex crystallites

Xue

Jia

Ren

et al. 2016

Journal of Cellular Plastics

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It is critical to broaden the applications of poly(L-lactic acid) foams by improving heat resistance properties. The stereocomplex crystallites that are formed by melt blending of poly(L-lactic acid)/polylactide possess high melting point of about 220 C and thus exhibit high heat resistance; therefore, the introduction of stereocomplex crystallites tends to improve the thermal stability of poly(lactic acid) foam. Unfortunately, using the solid-state foaming method, it was found that the expansion ratio of the obtained poly(lactic acid) foams was compromised with the value of 1.7 times once the stereocomplex crystallites were formed during the sample saturation stage. In this study, by applying a high compression molding temperature of 230 C, the as-prepared poly(L-lactic acid) and poly(L-lactic acid)/polylactide blends were amorphous. After being CO 2 saturated at a mild condition, the specimens were foamed at 90-160 C. The wide-angle X-ray diffraction profiles presented that the stereocomplex crystallites and PLA homocrystals were in-situ generated during the foaming process. It is observed that the in-situ formed stereocomplex crystallites could act as the physical cross-linking agent to stabilize the nucleated bubbles and suppress cell coalescence, resulting in the

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Synthesis and characterization of novel ABA triblock copolymers from L-lactide, glycolide, and PEG

Cited by 4 publications

References 12 publications

Biocompatible and Biodegradable Copolymer Stabilizers for Hydrofluoroalkane Dispersions: A Colloidal Probe Microscopy Investigation

Biocompatible and Biodegradable Copolymer Stabilizers for Hydrofluoroalkane Dispersions: A Colloidal Probe Microscopy Investigation

Fluorescently labeled degradable thermoplastic polyurethane elastomers: Visual evaluation for the degradation behavior

Improved expansion ratio and heat resistance of microcellular poly(L-lactide) foam via in-situ formation of stereocomplex crystallites

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