Competition between phase separation and crystallization in a PCL/PEG polymer blend captured by synchronized SAXS, WAXS, and DSC

Chuang, Wei‐Tsung; Jeng, U‐Ser; Sheu, Hwo‐Shuenn; Hong, Po‐Da

doi:10.1007/bf03219067

Cited by 50 publications

(38 citation statements)

References 35 publications

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“…The well-rounded spherulitic form of these PEO zones indicates that upon cooling, the PEO crystals are first to nucleate and grow into the large spherulites, after which the PCL crystallites fill in the remaining space. Similar structures have previously been recorded for polyoxymethylene [18] and PCL-based [19] blends incorporating PEO. To assess the distribution of the PEO throughout the PCL matrix, PCM is used.…”

Section: Blend Compositionssupporting

confidence: 84%

Bulk Compounding of PCL-PEO Blends for 3D Plotting of Scaffolds for Cardiovascular Tissue Engineering

G¹

2013

J Material Sci Eng

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Abstract3D plotting of micro-extruded filaments is a promising method for the additive manufacturing of porous scaffolds (for tissue engineering) in thermoplastic polymers. A much investigated polymer for degradable scaffolds is poly-ε-caprolactone (PCL). One of the remaining issues with the material is its inherent hydrophilicity, which leads to nonspecific protein adsorption. Specifically for cardiovascular applications, it has also been found that PCL is insufficiently flexible to mimic the mechanic-elastic behavior of the natural tissue. Earlier research has shown that blending with low molecular weight poly-ethylene-oxide (PEO) may offer an improvement in terms of both hydrophilicity and flexibility. Until now, solution-based blending has been used as a manufacturing method for these blends, since PCL and PEO are largely immiscible in the melt. This, however, is tedious work which yields only a few grams of material at a time. Therefore, in the current research, a method has been developed for the bulk compounding of PCL-PEO blends, using a twin-screw extruder. The manufactured blends were evaluated for composition, dispersion of the PEO and crystalline morphology. It was found that by re-compounding the blends after the first extrusion step, a good dispersion of the PEO within the PCL matrix was achieved.

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Section: Blend Compositionssupporting

confidence: 84%

Bulk Compounding of PCL-PEO Blends for 3D Plotting of Scaffolds for Cardiovascular Tissue Engineering

G¹

2013

J Material Sci Eng

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“…Storage temperature did not significantly affect the mechanical integrity, including specimens stored at 55 C which did exhibit a slight degradation in the modulus after 2 months. Group avoid the uncontrolled release that often plagues local delivery systems, differences in the Hildebrand constants and phase separation between the polymer components based on their relative rates of polymer crystallization [39][40][41] justified the use of PEG to induce domains within the cast blended polymer BVF composite to provide porosity via aqueous permeation, PEG dissolution, and extraction from the polymer matrix. 14 This intended polymer matrix skeletonization and porosity impacts the tobramycin release kinetics by transitioning device release mechanisms from aqueous permeation/dissolution-limited to drug diffusion-limited kinetics.…”

Section: Discussionmentioning

confidence: 99%

Molded polymer‐coated composite bone void filler improves tobramycin controlled release kinetics

Brooks

Sinclair²,

Davidoff

et al. 2013

J Biomed Mater Res

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Infection remains a significant problem associated with biomedical implants and orthopedic surgeries, especially in revision total joint replacements. Recent advances in antibiotic-releasing bone void fillers (BVF) provide new opportunities to address these types of device-related orthopedic infections that often lead to substantial economic burdens and reduced quality of life. We report improvements made in fabrication and scalability of an antibiotic-releasing polycaprolactone-calcium carbonate/phosphate ceramic composite BVF using a new solvent-free, molten-cast fabrication process. This strategy provides the ability to tailor drug release kinetics from the BVF composite based on modifications of the inorganic substrate and/or the polymeric component, allowing extended tobramycin release at bactericidal concentrations. The mechanical properties of the new BVF composite are comparable to many reported BVFs and validate the relative homogeneity of fabrication. Most importantly, fabrication quality controls are correlated with favorable drug release kinetics, providing bactericidal activity to 10 weeks in vitro when the polycaprolactone component exceeds 98% w/w of the total polymer fraction. Furthermore, in a time kill study, tobramycin-releasing composite fragments inhibited S. aureus growth over 48 h at inoculums as high as 10(9) CFU/mL. This customizable antibiotic-releasing BVF polymer-inorganic biomaterial should provide osseointegrative and osteoconductive properties while contributing antimicrobial protection to orthopedic sites requiring the use of bone void fillers.

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“…Competition between these two processes determines the final morphology. [17] In the case of crystalline/amorphous copolymers, weakly segregated microphase separation structure can be destroyed by crystallization, while strongly segregated microphase separation structure is maintained. In contrast, block copolymers containing only crystalline components are subjected to a competition in crystallization between different blocks.…”

Section: Introductionmentioning

confidence: 99%

Morphology and Melt Crystallization of PCL‐PEG Diblock Copolymers

Xu¹,

He²,

Wei³

et al. 2008

Macro Chemistry & Physics

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ROP of PCL was realized in the presence of mPEG with $\overline M _{\rm n}$ = 5 000, using Zn(La)2 as a catalyst. The resulting diblock copolymers with molar ratios of the CL/EO repeat units from 0.2–5.0 were characterized by DSC, WAXD, SEC, and 1H NMR. Melt crystallization was studied and analyzed with the Avrami equation. The spherulite growth rate G was determined at different crystallization temperatures. The G values were found to range between those of mPEG and PCL homopolymers. The morphology of an isothermally crystallized sample with CL/EO = 0.5 was examined. Spherulites with PCL embedded in PEG were observed, in contrast to concentric spherulites reported in the literature.

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Competition between phase separation and crystallization in a PCL/PEG polymer blend captured by synchronized SAXS, WAXS, and DSC

Cited by 50 publications

References 35 publications

Bulk Compounding of PCL-PEO Blends for 3D Plotting of Scaffolds for Cardiovascular Tissue Engineering

Bulk Compounding of PCL-PEO Blends for 3D Plotting of Scaffolds for Cardiovascular Tissue Engineering

Molded polymer‐coated composite bone void filler improves tobramycin controlled release kinetics

Morphology and Melt Crystallization of PCL‐PEG Diblock Copolymers

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