Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA, 19104, USA.
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Institute of Functional Materials, Donghua University, Shanghai, 201620, P. R. China.
Adv Mater. 2018 Oct;30(43):e1803847. doi: 10.1002/adma.201803847. Epub 2018 Sep 2.
Composite films consisting of wrinkles on top of the elastomeric poly(dimethylsiloxane) film and a thin layer of silica particles embedded at the bottom is prepared as on-demand mechanoresponsive smart windows. By carefully varying the wrinkle geometry, silica particle size, and stretching strain, different initial optical states and a large degree of optical transmittance change in the visible to near infrared range with a relatively small strain (as small as 10%) is achieved. The 10% pre-strain sample has shallow wrinkles with a low amplitude and shows moderate transmittance (60.5%) initially and the highest transmittance of 86.4% at 550 nm when stretched at the pre-strain level. Stretching beyond the pre-strain level leads to a drastic decrease of the transmittance at 550 nm, 39.7% and 70.8% with an additional 10% and 30% strain, respectively. The large drop of optical transmittance is the result of combined effects from the formation of secondary wrinkles and nanovoids generated around the particles. The 20% pre-strain sample has wrinkles with a moderate amplitude, showing 36.9% transmittance in the initial state, and the highest transmittance of 71.5% at 550 nm when stretched to the pre-strain level. Further stretching leads to increased opacity similar to that seen from the 10% pre-strain sample.
由顶部的弹性聚二甲基硅氧烷（PDMS）膜上的皱纹和底部嵌入的薄二氧化硅颗粒层组成的复合膜被制备成按需机械响应智能窗。通过仔细改变皱纹几何形状、二氧化硅颗粒尺寸和拉伸应变，可以在可见光到近红外范围内实现不同的初始光学状态和较大的透光率变化，应变相对较小（小至 10%）。10%预应变样品具有低振幅的浅皱纹，初始透光率适中（60.5%），在预应变水平拉伸时在 550nm 处具有最高透光率 86.4%。超过预应变水平的拉伸会导致在 550nm 处的透光率急剧下降，分别在额外的 10%和 30%应变下，透光率为 39.7%和 70.8%。光学透光率的大幅下降是由于二次皱纹的形成和颗粒周围纳米空隙的产生的综合影响。20%预应变样品具有中等振幅的皱纹，初始透光率为 36.9%，在拉伸至预应变水平时在 550nm 处具有最高透光率 71.5%。进一步拉伸会导致不透明度增加，类似于 10%预应变样品的情况。
