Wang Luling, Asher Sanford A
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
Chem Mater. 2009 Oct 13;21(19):4608-4613. doi: 10.1021/cm901666b.
We attached very small silica particles onto flexible monodisperse poly (N-isopropylacrylamide, PNIPAm) core particles synthesized by dispersion polymerization. These silica particles were attached to the partially swollen PNIPAm particles by the hydrolysis and condensation of tetraethoxysilane at 24 °C. The resulting silica particle-functionalized PNIPAm core particles show reversible swelling and shrinking as the temperature is cycled. These particles form close-packed-array photonic crystals as the solvent evaporates; the cores shrink to form a silica shell around the pure PNIPAm dry core particles as they close pack. The PNIPAm cores were removed by calcination, leaving a PC composed of essentially pure continuous silica shells. These silica shell photonic crystals Bragg diffract UV light at ~310 nm. The close packed particle interstices are continuous and are easily filled by water. In contrast, the silica shells are impervious to water because the process of making them results in a continuous shell of silica without holes.
我们将非常小的二氧化硅颗粒附着在通过分散聚合合成的柔性单分散聚（N-异丙基丙烯酰胺，PNIPAm）核颗粒上。这些二氧化硅颗粒在24℃下通过四乙氧基硅烷的水解和缩合附着在部分溶胀的PNIPAm颗粒上。随着温度循环，所得的二氧化硅颗粒功能化的PNIPAm核颗粒表现出可逆的溶胀和收缩。当溶剂蒸发时，这些颗粒形成密排阵列光子晶体；当它们密排时，核收缩形成围绕纯PNIPAm干核颗粒的二氧化硅壳。通过煅烧去除PNIPAm核，留下由基本上纯的连续二氧化硅壳组成的光子晶体。这些二氧化硅壳光子晶体在约310nm处对紫外光进行布拉格衍射。紧密堆积的颗粒间隙是连续的，并且很容易被水填充。相比之下，二氧化硅壳对水是不可渗透的，因为制造它们的过程会产生没有孔的连续二氧化硅壳。
