An elegant and precise method to fabricate asymmetrical structures and/or gradient structures was developed based on a vapor-phase sublimation and deposition process. The fabricated materials exhibited versatility and had advantages such as well-controlled pore structures and functional properties ranging from an asymmetrical distribution to a gradient hierarchy; precisely addressed interface chemistries and properties for the constructed materials; and flexibility to produce the materials at multiple scales. By using a time-dependent customization parameter to control the bulk size and/or the dispersion of molecules, fabrication of the materials was demonstrated, producing particles with hierarchical pore structures and with bulk sizes ranging from >500 μm to submicrons, as well as gradients with both continuously varied porosity and chemical functionality that were demonstrated to be in a controlled direction and varied across multiple scales (centimeter, millimeter, and micrometer). By exploiting chemical vapor deposition to enable multicomponent copolymerization during the fabrication process, multifunctional poly-p-xylylenes formed building blocks for these hierarchical materials and provided the defined surface chemistries. The proposed functional hierarchical materials were constructed and assembled in the vapor phase and in one step, and prospective materials produced by this method are expected to have novel properties and unlimited applications.

中文翻译：

---

基于汽相升华和沉积工艺的多尺度条件下聚对二甲苯的不对称和梯度层次结构的制备

基于气相升华和沉积工艺，开发了一种优雅而精确的方法来制造不对称结构和/或梯度结构。制成的材料具有通用性，并具有良好的优势，例如，孔结构得到良好控制，功能特性从不对称分布到梯度层次不等。精确解决了所构造材料的界面化学性质和特性；灵活地生产多种规模的材料。通过使用随时间变化的自定义参数来控制分子的体积和/或分散，展示了材料的制造过程，生产出具有分层孔结构且体积范围从> 500μm到亚微米的颗粒，以及具有连续变化的孔隙率和化学功能的梯度，这些梯度被证明是在受控的方向上并在多个比例（厘米，毫米和微米）之间变化。通过利用化学气相沉积技术在制造过程中实现多组分共聚，多功能多对二甲苯形成了这些分层材料的结构单元，并提供了定义的表面化学性质。所提出的功能性分级材料在气相中一步一步地构建和组装，通过这种方法生产的预期材料有望具有新颖的性能和无限的应用范围。