Electrospun Poly(ε‐caprolactone)/Polyhedral Oligomeric Silsesquioxane‐Based Copolymer Blends: Evolution of Fiber Internal Structures

Abstract

This study reports the structural transition of electrospun poly(ε-caprolactone) (PCL)/poly[(propylmethacryl-heptaisobutyl-polyhedral oligomeric silsesquioxane)-co-(methyl meth-acrylate)] (POSS-MMA) blends, from PCL-rich fibers, to bicontinuous PCL core/POSS-MMA shell fibers, to POSS-MMA-rich fibers with a discontinuous PCL inner phase. A ternary phase diagram depicting the electrospinnability of PCL/POSS-MMA solutions is constructed by evaluating the morphological features of fibers electrospun from solutions with various concentrations and PCL/POSS-MMA blend ratios. X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry are further used to characterize the electrospun PCL/POSS-MMA hybrid fibers. These physicochemical characterization results are thoroughly discussed to understand the internal structures of the hybrid fibers, which are directly correlated to the phase separation behavior of the electrospun solutions. The current study provides further insight into the complex phase behavior of POSS-copolymer-based systems, which hold great potential for a broad spectrum of biomedical applications.

Molecular Architecture and Enhanced Thermal Stability of Electrospun Poly(ε‐caprolactone)/Aminopropyl Isobutyl Polyhedral Oligomeric Silsesquioxane Hybrid Fibers

“…The PCL‐core/AMPOSS‐shell structure can therefore be produced, in particular, when the AMPOSS content is sufficiently large (e.g., 30 wt%) to form a structurally intact outer layer. The formation of such a core/shell structure is again due to the radial phase separation along the cross section of the spinning liquid jet during electrospinning, which is comparable to that reported for electrospun PCL/m‐iBuPOSS and PCL/POSS‐MMA systems . The rapid accumulation of the POSS‐based phase on or near the outer surface of the electrospinning liquid jet is the result of the low surface energy of POSS.…”

“…Figure shows the diffraction patterns for electrospun PCL/AMPOSS fibers at various mass ratios of PCL/AMPOSS. For the neat PCL fiber sample, two peaks typical of PCL crystals at 2θ = 21.4° and 23.8° appear, as shown in Figure A, which can be attributed to the [110] and [200] lattice planes, respectively . For all PCL/AMPOSS fibers, as shown in Figure B–E, the diffractograms exhibit Bragg angles almost identical to those observed for neat PCL, suggesting that the PCL crystal structure is not significantly altered by adding AMPOSS.…”

“…The formation of a structurally protective m‐iBuPOSS‐rich crust was further confirmed by an X‐ray photoelectron spectroscopy studies, suggesting that the radial phase separation of PCL/m‐iBuPOSS does occur in the electrospinning liquid jet . Radial phase separation in a spinning jet composed of PCL/POSS‐based copolymers has also been found in the electrospinning of PCL/poly[(propylmethacryl‐heptaisobutyl‐polyhedral oligomeric silsesquioxane)‐co‐(methyl methacrylate)] (POSS‐MMA) blends . By increasing the POSS‐MMA content above 40 wt%, electrospun bicontinuous PCL core/POSS‐MMA shell fibers have been produced even through single spinneret electrospinning.…”

“…By increasing the POSS‐MMA content above 40 wt%, electrospun bicontinuous PCL core/POSS‐MMA shell fibers have been produced even through single spinneret electrospinning. Here, the two components (i.e., PCL and POSS‐MMA) are radially phase separated along the long axis of the spinning liquid jet, which allows the formation of core/shell fibers using a single spinneret electrospinning method …”

New Generation of Tunable Bioactive Shape Memory Mats Integrated with Genetically Engineered Proteins

“…However, further increase of the weight ratio will result in discontinuous phase. [23,24] Moreover, phase separation of polymers depends on the environmental conditions during spinning. At higher relative humidity, the rate of solidification is faster due to water molecules which will act as a non-solvent to polymers.…”