研究目的
To develop a method for simultaneously controlling the pore diameters and heights of periodic porous polymer films by adjusting the flow behaviors of polymer colloids and curing resin precursors, without using differently sized colloids or varying precursor amounts.
研究成果
The study successfully demonstrates a novel method to simultaneously control pore diameters and heights of periodic porous polymer films by adjusting the flow behaviors of colloids and curing resins through temperature variation or solvent addition. This leads to significant changes in surface wettability and photonic properties, such as water contact angles and light reflectance/transmittance. The method is straightforward, does not require additional steps or materials, and can be applied to various resins, offering potential for tunable film characteristics in applications like sensors and membranes.
研究不足
The method may be limited by the specific properties of the resins and colloids used; for instance, PDMS precursors did not show temperature dependence due to high viscosity and fast gelation. The deformation and gelation times must be carefully balanced, and reproducibility could be affected by factors like precursor viscosity and curing conditions. The approach may not be universally applicable to all polymer systems without optimization.
1：Experimental Design and Method Selection:
The study uses replication methods to prepare periodic porous films by embedding phenolic resin or PDMS precursors into polystyrene colloidal crystal monolayers. Flow behaviors are controlled by varying curing temperatures (≥ Tg of PS) or adding tetrahydrofuran (THF) to precursors to alter viscosity and colloid deformation.
2：Sample Selection and Data Sources:
Monodisperse polystyrene colloids of diameters
3：9, 3, 2, and 1 μm are synthesized and used to form colloidal crystal monolayers on silicon wafers. Phenolic resin and PDMS precursors are embedded into these monolayers. List of Experimental Equipment and Materials:
Materials include ethanol, dioctyl sulfosuccinate sodium salt, polyvinylpyrrolidone, styrene, 1-butanol, sodium 4-vinylbenzenesulfonate, 2-methoxyethanol, hydroxypropyl cellulose, benzoyl peroxide, polydimethylsiloxane precursor (Sylgard? 184), α,α′-azobis(isobutyronitrile), tetrahydrofuran, acetone, phenolic resin precursor (CB-8057), silicon wafers, and cover glass. Equipment includes optical microscope (BX 51, Olympus), scanning electron microscope (SEM, S-4800, HITACHI), UV-Vis spectrophotometer (V-670, JASCO) with integrating sphere, and goniometer (PHOENIX-150, Surface Electro Optics).
4：Experimental Procedures and Operational Workflow:
PS colloids are synthesized via dispersion polymerization, purified, and used to form colloidal crystal monolayers by dropping butanol-PS dispersions on water and transferring to substrates. For phenolic resin films, precursor solutions in ethanol are dropped on monolayers, dried, cured at 100–160°C for 6h under vacuum, and PS is removed with THF. For PDMS films, precursor-THF mixtures are poured onto monolayers, cured at 25°C for 24h, and PS is removed with acetone.
5：Data Analysis Methods:
Morphologies are analyzed using SEM and optical microscopy. Pore diameters and heights are measured from SEM images. Water contact angles are measured with a goniometer. Reflectance and transmittance spectra are obtained using UV-Vis spectrophotometry. Areal fractions are estimated from SEM images, and contact angles are modeled using the Cassie-Baxter equation.
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