Copolymers of<i>rac</i>-Lactide and ε -Caprolactone: Conventional Copolymerization vs. Macroinitiator Copolymerization

Moravek, Scott J.; Storey, Robson F.

doi:10.1080/10601320902720568

Cited by 8 publications

(7 citation statements)

References 10 publications

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“…LA is hydrophobic, biocompatible and susceptible to hydrolytic degradation, in addition to being amorphous when polymerized, and the low concentration of LA favors a random polymerization despite reactivity differences. 30,31 Two block copolymers incorporating 10 mol % LA within the PCL blocks were synthesized; poly(ethylene oxide)-b-poly(ε-caprolactone-r-D,L-lactide), is denoted OCLA (X, Y, Z), where X (2 kg/mol) is the size of PEO and Y and Z are the respective masses of polymerized caprolactone and lactide. Polydispersity indices and block ratios for all of the synthesized polymers were respectively assessed using GPC and NMR spectroscopy as listed in Table 1 (and detailed in the Supporting Information, part S1).…”

Section: Resultsmentioning

confidence: 99%

Curvature-Coupled Hydration of Semicrystalline Polymer Amphiphiles Yields flexible Worm Micelles but Favors Rigid Vesicles: Polycaprolactone-Based Block Copolymers

et al. 2010

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Crystallization processes are in general sensitive to detailed conditions, but our present understanding of underlying mechanisms is insufficient. A crystallizable chain within a diblock copolymer assembly is expected to couple curvature to crystallization and thereby impact rigidity as well as preferred morphology, but the effects on dispersed phases have remained unclear. The hydrophobic polymer polycaprolactone (PCL) is semi-crystalline in bulk (T m = 60°C) and is shown here to generate flexible worm micelles or rigid vesicles in water from several dozen polyethyleneoxide-based diblocks (PEO-PCL). Despite the fact that `worms' have a mean curvature between that of vesicles and spherical micelles, `worms' are seen only within a narrow, process-dependent wedge of morphological phase space that is deep within the vesicle phase. Fluorescence imaging shows worms are predominantly in one of two states -either entirely flexible with dynamic thermal undulations or fully rigid; only a few worms appear rigid at room temperature (T << T m ), indicating suppression of crystallization by both curvature and PCL hydration. Worm rigidification, which depends on molecular weight, is also prevented by copolymerization of caprolactone with just 10% racemic lactide that otherwise has little impact on bulk crystallinity. In contrast to worms, vesicles of PEO-PCL are always rigid and typically leaky. Defects between crystallite domains induce dislocation-roughening with focal leakiness although select PEO-PCL -which classical surfactant arguments would predict make worms -yield vesicles that retain encapsulant and appear smooth, suggesting a gel or glassy state. Hydration in dispersion thus tends to selectively soften high curvature microphases.Keywords block copolymer; worm micelle; polymersome; crystallinity Corresponding: discher@seas.upenn.edu. Supporting Information. Molecular details of all polymers synthesized, calculation of polymer distribution in assemblies, AFM and fluorescence microscopy images, DLS and dye encapsulation studies, movies of worm micelles, persistence length measurement of worm micelles, procedure for measurement of contour lengths, and phase contrast images of OCL (2, 13.5) can be found in Supporting Information. Supporting Information is available free of charge on the internet at

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Section: Resultsmentioning

confidence: 99%

Curvature-Coupled Hydration of Semicrystalline Polymer Amphiphiles Yields flexible Worm Micelles but Favors Rigid Vesicles: Polycaprolactone-Based Block Copolymers

et al. 2010

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“…Copolymerization seems to give the widest opportunity for tuning the properties of the final block, grafted or random copolymer. Cyclic esters as glycolide, ɛ‐caprolactone, dioxanone, trimethylene carbonate, etc. are very popular monomers for copolymerization with LA forming random copolymers.…”

Section: Introductionmentioning

confidence: 99%

Screening of metal catalysts influence on the synthesis, structure, properties, and biodegradation of PLA‐PBA triblock copolymers obtained in melt

Kundys

Plichta

Florjańczyk

et al. 2015

J. Polym. Sci. Part A: Polym. Chem.

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The synthesis of ABA type triblock copolymers comprising poly(1,4‐butylene adipate) macroinitiator and polylactide segments is described in this article. Acetylacetonates of various low‐toxic metals: Li, Mg, Ca, Zn, Fe, and Zr are used as catalysts. The course of polymerization, microstructure, thermal properties, and biodegradation of the copolymers obtained are analyzed based on the electronegativity of the metal used. The macroinitiator is completely incorporated into the major products, however, linear and cyclic lactide homopolymers and copolymers are present because of moisture presence and transesterification processes. The efficiency of side reactions depends on the catalyst used. The highest molar mass of copolymer is obtained with a Zr‐based catalyst. The efficacy of polylactide racemization is higher for catalysts comprising the metal of lower electronegativity. Under thermal degradation conditions the polylactide segment degrades before the macroinitiator one. The copolymers studied undergo faster biodegradation than polylactide and they can decompose in compost within 16 weeks. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1444–1456

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“…The final product has a distribution of chain lengths that can be characterized by an average number of CL units added. The cocatalyst plays a strong role, allowing the opening of the lactone ring, thus initiating the growth of the polymer chain, , since the ROP is a controlled process the MW is expected to be equal to the ratio between ε-caprolactone and alcohol moles. Usually 1-dodecanol or other high boiling point alcohols are used as cocatalysts in order to reach a good control of the final polymer MW .…”

Section: Introductionmentioning

confidence: 99%

ε-Caprolactone-Based Macromonomers Suitable for Biodegradable Nanoparticles Synthesis through Free Radical Polymerization

et al. 2011

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New ε-caprolactone (CL)-based materials were synthesized. Bulk ring-opening polymerization of ε-caprolactone with 2-hydroxyethyl methacrylate (HEMA) as cocatalyst was carried out to produce various macromonomers composed of HEMA functionalized with 1–10 CL units. All of the HEMA-CL macromonomers have been characterized by size exclusion chromatography (SEC) and 1H NMR. For SEC analysis universal calibration was applied, and Mark–Houwink parameters for poly(HEMA-g-CL3) were obtained. Macromonomers with different CL chain length were polymerized through free radical polymerization, in both batch and semibatch emulsion polymerization to produce CL-based nanoparticles (NPs) with narrow particle size distribution. Various reactions parameters were investigated, namely the type of the emulsifier, the feeding conditions, and the macromonomer chain length. Finally, a simple and qualitative degradation study of selected samples was carried out in order to verify the degradability of these CL-based NPs.

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Copolymers ofrac-Lactide and ε -Caprolactone: Conventional Copolymerization vs. Macroinitiator Copolymerization

Cited by 8 publications

References 10 publications

Curvature-Coupled Hydration of Semicrystalline Polymer Amphiphiles Yields flexible Worm Micelles but Favors Rigid Vesicles: Polycaprolactone-Based Block Copolymers

Curvature-Coupled Hydration of Semicrystalline Polymer Amphiphiles Yields flexible Worm Micelles but Favors Rigid Vesicles: Polycaprolactone-Based Block Copolymers

Screening of metal catalysts influence on the synthesis, structure, properties, and biodegradation of PLA‐PBA triblock copolymers obtained in melt

ε-Caprolactone-Based Macromonomers Suitable for Biodegradable Nanoparticles Synthesis through Free Radical Polymerization

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