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Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced Phase Separation in nanoconfinement

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ABSTRACT

Phase separation of a polymer solution exhibits a peculiar behavior when induced in a nanoconfinement. The energetic constraints introduce additional interactions between the polymer segments that reduce the number of available configurations. In our work, this effect is exploited in a one-step strategy called nanoconfined-Thermally Induced Phase Separation (nc-TIPS) to promote the crystallization of polymer chains into nanocapsular structures of controlled size and shell thickness. This is accomplished by performing a quench step of a low-concentrated PLLA-dioxane-water solution included in emulsions of mean droplet size <500 nm acting as nanodomains. The control of nanoconfinement conditions enables not only the production of nanocapsules with a minimum mean particle diameter of 70 nm but also the tunability of shell thickness and its crystallinity degree. The specific properties of the developed nanocapsular architectures have important implications on release mechanism and loading capability of hydrophilic and lipophilic payload compounds.

No MeSH data available.


Crystallinity grade analysis by DSC and XRD.(a) DSC heating curves of PLLA nanocapsules at different polymer concentrations, from the top: 0.1- 0.5- 1- 1.5% wt/v–PLLA Raw; (b) Table reports DSC data in detail and the crystallinity grade, showing how the polymer concentration can influence crystallization phenomena (DSC heating rate: 5 °C/min); (c) XRD patterns at different PLLA concentrations from 0.1% wt/v to 1.5% wt/v; (d) Degree of crystallinity versus PLLA concentration.
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f3: Crystallinity grade analysis by DSC and XRD.(a) DSC heating curves of PLLA nanocapsules at different polymer concentrations, from the top: 0.1- 0.5- 1- 1.5% wt/v–PLLA Raw; (b) Table reports DSC data in detail and the crystallinity grade, showing how the polymer concentration can influence crystallization phenomena (DSC heating rate: 5 °C/min); (c) XRD patterns at different PLLA concentrations from 0.1% wt/v to 1.5% wt/v; (d) Degree of crystallinity versus PLLA concentration.

Mentions: In our approach, a semicrystalline morphology is obtained at very high cooling rates, more than 40 °C/min, contrary to the general observations above reported proving that a different phenomenon is interfering with the thermodynamic involved in the nanocapsule formation. In these perspectives a calorimetric study was performed and DSC curves at a cooling/heating rate of 5 °C/min obtained for the produced NCs are showed in Fig. 3a, whereas the thermal results are listed in Fig. 3b.


Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced Phase Separation in nanoconfinement
Crystallinity grade analysis by DSC and XRD.(a) DSC heating curves of PLLA nanocapsules at different polymer concentrations, from the top: 0.1- 0.5- 1- 1.5% wt/v–PLLA Raw; (b) Table reports DSC data in detail and the crystallinity grade, showing how the polymer concentration can influence crystallization phenomena (DSC heating rate: 5 °C/min); (c) XRD patterns at different PLLA concentrations from 0.1% wt/v to 1.5% wt/v; (d) Degree of crystallinity versus PLLA concentration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015022&req=5

f3: Crystallinity grade analysis by DSC and XRD.(a) DSC heating curves of PLLA nanocapsules at different polymer concentrations, from the top: 0.1- 0.5- 1- 1.5% wt/v–PLLA Raw; (b) Table reports DSC data in detail and the crystallinity grade, showing how the polymer concentration can influence crystallization phenomena (DSC heating rate: 5 °C/min); (c) XRD patterns at different PLLA concentrations from 0.1% wt/v to 1.5% wt/v; (d) Degree of crystallinity versus PLLA concentration.
Mentions: In our approach, a semicrystalline morphology is obtained at very high cooling rates, more than 40 °C/min, contrary to the general observations above reported proving that a different phenomenon is interfering with the thermodynamic involved in the nanocapsule formation. In these perspectives a calorimetric study was performed and DSC curves at a cooling/heating rate of 5 °C/min obtained for the produced NCs are showed in Fig. 3a, whereas the thermal results are listed in Fig. 3b.

View Article: PubMed Central - PubMed

ABSTRACT

Phase separation of a polymer solution exhibits a peculiar behavior when induced in a nanoconfinement. The energetic constraints introduce additional interactions between the polymer segments that reduce the number of available configurations. In our work, this effect is exploited in a one-step strategy called nanoconfined-Thermally Induced Phase Separation (nc-TIPS) to promote the crystallization of polymer chains into nanocapsular structures of controlled size and shell thickness. This is accomplished by performing a quench step of a low-concentrated PLLA-dioxane-water solution included in emulsions of mean droplet size <500 nm acting as nanodomains. The control of nanoconfinement conditions enables not only the production of nanocapsules with a minimum mean particle diameter of 70 nm but also the tunability of shell thickness and its crystallinity degree. The specific properties of the developed nanocapsular architectures have important implications on release mechanism and loading capability of hydrophilic and lipophilic payload compounds.

No MeSH data available.