利用氣相沉積技術製備並調控顆粒之非對稱多孔結構

Abstract

非對稱結構之多孔材料因其機械、化學性質可透過製程操控，而被廣為研究，並廣泛應用於吸附劑、非勻相觸媒、膜過濾系統、表面疏水改質、藥物承載與傳遞等領域中。本篇研究提出一種創新的製備方法，基於氣相昇華與沉積機制由物質非對稱分布創造非對稱多孔結構，其展現多樣性與多項優點，包括可操控的孔洞結構及功能性；另外，透過調控時間相依製程參數，可控制材料本體尺寸或分子分布；本研究以製備> 500 µm至次微米微粒展示此項技術與其內部非對稱孔洞結構。製備過程中氣相聚對二甲苯（poly-p-xylylene）沉積於昇華球狀模板，同時固體模板昇華產生氣體逸散，擾動poly-p-xylylene沉積與聚合，因而留下孔洞，因此可藉由調控模板之昇華速度來控制多孔顆粒之孔隙度。同時根據液體昇華及界面特性，以快速冷凍複合物得穩定球狀模板，進行氣相昇華/沉積生成poly-p-xylylene顆粒，並由昇華氣體及非昇華液體產生非對稱孔洞。此外，以瞬間凝固法中斷質量傳遞將功能性物質限制在結構材料中，便功能化多孔顆粒，並透過螢光訊號觀察分子分布。本研究提供一套全新的方法製備功能性非對稱材料，在氣相中一步構建和組裝，並預期此材料有無限應用可能。

Asymmetrically structured porous materials with controlled mechanical or chemical properties have been extensively studied and applied to adsorbents, heterogeneous catalysts, membrane filtration systems, surface hydrophobic modification, drug loading and delivery. Here we reported an innovative method for the fabrication of asymmetrical porous structures based on a vapor-phased sublimation and deposition process. The fabricated materials exhibited versatility and advantages being well-controlled pores structures and functional properties from an asymmetrical distribution. By using a time dependent customization parameter to control the bulk size or the dispersion of molecules, the fabrication of materials were demonstrated to produce particles with asymmetrical pores structure and with bulk size ranging from >500 µm to submicron. The particles were constructed via vapor depositions of poly-p-xylylenes on sublimating solid template. Pore structure was formed by the releasing sublimated vapor of the solid template disrupted poly-p-xylylene deposition and polymerization, thus allowing the control of porosity by modulating the sublimation speed of the template. Also according to the sublimation and interface properties of liquids, we got the stable composite as the sublimation template by freezing, and the proposed poly-p-xylylene particles is prepared subsequently by vapor sublimation/deposition mechanism to yield asymmetrical porous structure caused by the sublimated vapors and the non-sublimable liquid during the fabrication process. And the functional substances were confined within the structural materials based on a timed solidification of mass transport in transient regime and were observed through the fluorescence signals. The proposed functional asymmetrical materials were constructed and assembled in vapor phase and in one step, and prospective materials produced by the method with novel properties are expected with unlimited applications.