Istituto di Fisica Applicata N. Carrara, IFAC-CNR, 50019 Sesto Fiorentino, Firenze, Italy.
Nat Commun. 2013;4:1557. doi: 10.1038/ncomms2564.
Meso/micro-porous solids, such as zeolites, are complex materials used in an impressive range of applications. Here we photo-polymerized ethylene using non-catalytic high-pressure techniques at 0.5-1.5 GPa under ultraviolet (351-364 nm) irradiation on a sub-nanometre scale in the channels of a pure SiO2 zeolite, silicalite, to obtain a unique nano-composite material with drastically modified mechanical properties. The structure obtained contains single polyethylene chains, which adapt very well to the confining channels as shown by optical spectroscopy and X-ray diffraction. The formation of this nano-composite results in significant increases in bulk modulus and density, and the thermal expansion coefficient changes sign from negative to positive with respect to silicalite. Mechanical properties may thus be tuned by varying the amount of polymerized ethylene. Our findings could allow the high-pressure, catalyst-free synthesis of a unique generation of technological, functional materials based on simple hydrocarbons polymerized in confining meso/micro-porous solids.
中孔/微孔固体，如沸石，是在广泛的应用中使用的复杂材料。在这里，我们在纯二氧化硅沸石硅沸石的通道中，在亚纳米尺度上使用非催化高压技术在 0.5-1.5 GPa 下和紫外线（351-364nm）照射下光聚合乙烯，以获得具有显着改性机械性能的独特纳米复合材料。通过光学光谱和 X 射线衍射显示，获得的结构包含单聚乙烯链，其非常适应约束通道。这种纳米复合材料的形成导致体弹性模量和密度的显著增加，并且热膨胀系数相对于硅沸石从负变为正。通过改变聚合的乙烯的量，可以调节机械性能。我们的发现可以允许在高压、无催化剂的条件下，在限制中孔/微孔固体中聚合的简单碳氢化合物的基础上，合成独特的新一代技术功能材料。
