Smart shape-memory polymers can memorize and recover their permanent shape in response to an external stimulus (for example, heat). They have been extensively exploited for a wide spectrum of applications ranging from biomedical devices to aerospace morphing structures. However, most of the existing shape-memory polymers are thermoresponsive and their performance is hindered by heat-demanding programming and recovery steps. Although pressure is an easily adjustable process variable such as temperature, pressure-responsive shape-memory polymers are largely unexplored. Here we report a series of shape-memory polymers that enable unusual ‘cold' programming and instantaneous shape recovery triggered by applying a contact pressure at ambient conditions. Moreover, the interdisciplinary integration of scientific principles drawn from two disparate fields—the fast-growing photonic crystal and shape-memory polymer technologies—enables fabrication of reconfigurable photonic crystals and simultaneously provides a simple and sensitive optical technique for investigating the intriguing shape-memory effects at nanoscale.

A new type of shape-memory polymer (SMP) is developed by integrating scientific principles drawn from two disparate fields: the fast-growing photonic crystal and SMP technologies. This new SMP enables room-temperature operation for the entire shape-memory cycle and instantaneous shape recovery triggered by exposure to a variety of organic vapors.

The Taguchi method, a statistical design with an L8 orthogonal array, was adopted to optimize the synthetic conditions of mesoporous silica nanoparticles (MSNs) with respect to particle size and structural properties. The amount of the silica source (i.e., tetraethoxysilane), pH value, and reaction time were selected as significant parameters affecting the size and structural properties of the synthesized MSNs. Particle sizes ranging from 17 to 247 nm were successfully controlled by the Taguchi method, and the statistical data based on experimental results indicated that the pH value of the silica/surfactant precursor solution had a greater influence (57%) on particle size than did reaction time and the TEOS amount (29% and 13%, respectively). The effects of individual parameters on particle size and structural properties, such as surface area and structural ordering, were also investigated by changing one parameter at a time. We concluded that the pH value strongly affected mesostructural ordering and particle size. Longer reaction times in basic conditions had little effect on structural ordering but caused erosion of the MSN silica framework, resulting in smaller particle sizes. The minimum amount of TEOS for ordered MSNs was 5 mL, and more TEOS slightly increased the particle size of the synthesized MSNs. The rational design and systematic investigation of synthetic conditions for MSNs with controllable particle sizes and structural properties presented in this study show great potential for MSN-based catalytic and biomedical applications.

Here we report the synthesis of mesoporous metal oxide materials with various compositions by assembly of spherical polymeric micelles consisting of triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-PVP-b-PEO) with three chemically distinct units. The PVP block interacts strongly with the inorganic precursors for the target compositions. The hydrophobic PS block is kinetically frozen in the precursor solutions, enabling the spherical micelles to remain in a stable form. The frozen PS cores serve as templates for preparing robust mesoporous materials. The PEO corona helps the micelles to stay well dispersed in the precursor solutions, which plays a key role in the orderly arrangement of the micelles during solvent evaporation. This approach is based on assembly of the stable micelles using a simple, highly reproducible method and is widely applicable toward numerous compositions that are difficult for the formation of mesoporous structures.