Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010
Electronic Supplementary Information
Coaxial Electrospinning with Organic Solvent for Controlling
the Self-assembled Nanoparticle Size
Deng-Guang Yu, a* Li-Min Zhu, a* S-W Annie Bligh, b Christopher Branford-White, b
Kenneth White, b
a College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
b Institute for Health Research and Policy, London Metropolitan University, London, N7 8DB, UK
* To whom correspondence should be addressed, email: [email protected]; [email protected]
S1 Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010
1. Experimental
1.1. Materials
Polyvinylpyrrolidone K60 (PVP K60, Mw =360,000) was purchased from BASF
Corp. (Shanghai, China); Naproxen (NAP) was obtained from Shanghai Greentech
Industries Co., Ltd. (Shanghai, China); Tristearin (GTS) was purchased from Tokyo
Chemical Industry Co., Ltd. (Tokyo, Japan); Anhydrous ethanol and chloroform were provided by Shanghai Shiyi Chemicals Reagent Co., Ltd. (Shanghai, China). All other chemicals used were analytical grade.
1.2. Electrospinning processes
A co-dissolving solution of PVP K60, GTS and NAP in chloroform with a ratio of 12 %: 2%: 0.5 % (w/v) was prepared as the core electrospinnable liquid, and anhydrous ethanol was used as the sheath fluid.
The flow rate of the core solutions was controlled by a single syringe infusion pump (Cole–Parmer®, USA) and was fixed at 2.0 cm3/h. The high voltage was supplied by a high voltage power generator (Shanghai Sute Electrical Co., Ltd) and was fixed at 15 kV. The fibers accepted on a metal collector wrapped with aluminum foil kept a fixed distance of 20 cm away from the needle tip of coaxial electrospinning head (self-made). The flow rates of the sheath ethanol were manipulated by another syringe infusion pump and 0, 0.5, 1.0 and 2.0 mol/h were conducted. The coaxial electrospinning processes with sheath ethanol were recorded using a digital video recorder (PowerShot A640, Canon, Japan) under different magnifications.
S2 Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010
1.3. Characterization
Field emission scanning electron microscope (FESEM)
The morphology of the surface and the cross-sections of the nanofiber mats were assessed using a S-4800 field emission scanning electron microscope (Hitachi, Japan).
The average fiber diameter was determined by measuring diameters of composite nanofibers over 100 points from FESEM images using Image J software (National
Institutes of Health, USA). Before carbon coating, the cross-sections of the nanofiber mats were prepared by placing them into liquid nitrogen for over 15 minutes, and then they were broken manually.
Scanning Probe Microscope (SPM)
A slide glass fixed on a grounded electrode of aluminum foil was used to collect
the electrospun composite fibers for about 10 s. A drop of water from a micro-injector was placed on the collected fibers. After drying, the self-assembly scene was observed using a DI-NSIV scanning force microscope (Digital Instruments).
Transmission electron microscopy (TEM)
TEM images of the samples were taken on a JEM 2100F field-emission transmission electron microscope (JEOL, Japan). Composite nanofiber mats (0.1g) were placed in 100 cm3 water for self-assembly. One drop of the self-assembled systems was spread onto a carbon coated thin film on 200 mesh copper grids.
Static and dynamic laser scanning (SDLC)
Average hydrodynamic diameter and size distribution of the self-assembled particles were determined using BI-200SM static and dynamic light scattering (SDLC)
S3 Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010 instruments (Brookhaven Instruments Corporation, Austin, Texas USA)
The samples were prepared by putting 0.1 g of the composite fiber mats in 100 cm3 water to self-assemble.
Polarization microscope
The samples were prepared according to methods mentioned in SPM section.
The self-assembly scenes were observed under polarized light using an XP-700 polarized optical microscope (Shanghai Changfang Optical Instrument Co., Ltd). The microscope was connected to a digital video recorder (PowerShot A640, Canon,
Japan). The magnification was 25 × 14.
S4 Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010
Figures
Figure S1. Schematic diagram of coaxial electrospinning process with sheath solvent.
Figure S2. Thermograms from differential scanning calorimetry.
S5 Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010
Figure S3. Attenuated total reflectance Fourier transform infrared spectra.
Figure S4. Typical static and dynamic laser scanning (SDLC) results of self-assembled nanoparticles from (A) F1, (B) F2, (C) F3 and (D) F4.
S6 Supplementary Material (ESI) for Chemical Communications This journal is (c) The Royal Society of Chemistry 2010
Figure S5. Photographs of the self-assembly process of composite nanofibers F2. The self-assembly process is shown in sequence from 1 to 6.
Figure S6. Coaxial electrospinning process with superfluous sheath solvent (A) and the resulted composite nanofibers (B). The ratio of sheath to core flow rate was 1.5, under which spindle-on-a-string morphology occurred and the diameter distributions of nanofibers became poorer although there were even smaller.
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