Smart Materials

摘要

Smart Materials are able to respond to changes in their environment in a predetermined way, and research in the field of functional materials is often motivated by potential applications. Smart polymers are especially of technological significance in view of the grand global challenges including energy generation and storage, sustainability, and healthcare. Being smart also involves the individual tailoring of properties and functions to specific purposes. Therefore, smart materials’ design requires an immensely broad approach. In this special issue, emphasis is given to responsive polymers, shape-memory polymers, nano-/micro-sized polymeric objectives, and application-driven materials. In addition, fabrication schemes of smart materials are considered. Among all the intelligent materials, polymers may be most readily responsive to environmental stimulation, as their functional groups can be tailored to accommodate to a fascinating range of stimulation modes. Song and co-workers (DOI: 10.1002/cphc.201701367) found that the spontaneous emission of a perovskite embedded in polymer opal structures exhibits clear amplified signatures. Wang's team (DOI: 10.1002/cphc.201800095) showed how to obtain a low background for early diagnosis of diseases through electrochemically responsive superhydrophilic surfaces exhibiting specific cell capture and release with high yields and extremely low nonspecific adhesion. While some polymers modify their behavior in reaction to a given trigger, most processes in daily life are reliant on responsiveness to multiple stimuli. Gianneschi, Abbott, and co-workers (DOI: 10.1002/cphc.201800106) taught how to manipulate multi-scale responses of liquid crystals by interfacial assemblies of cleavable homopolymers with mesogenic side chains that can be split upon exposure to either H2O2 or UV light. Wang's group (DOI: 10.1002/cphc.201701145) constructed photo- and thermal dually responsive smart surfaces by grafting silicon nanowire arrays onto a copolymer of spiropyran and N-isopropylacrylamide to overcome the low efficiency of cancer-cell capture and release by single-responsive smart surfaces. Deng, Zhong, and co-workers (DOI: 10.1002/cphc.201701367) developed integrated multifunctional micelles through co-self-assembly of poly(ethylene glycol)-b-poly(l-lysine) derivatives with natural ferulic acid or lipoic acid. Apart from the potential applications in biomedicine, the petroleum industry is undoubtedly another promising arena to embrace the use of responsive polymers, so as to satisfy the variation of temperature and salinity when going deep into the underground formation. Su and Feng (DOI: 10.1002/cphc.201800190) reviewed the cutting-edge development of unique thermo-viscosifying polymers and up-to-date laboratory trials at various stages of oil and gas production. A method that allows controlled manipulation and shape-memory effect (SME) quantification of individual micro- and nano-objects in analogy to macroscopic thermomechanical test procedures is introduced by Lendlein et al. (DOI: 10.1002/cphc.201701362). An atomic force microscope is applied to address individual electro-spun poly(ether urethane) (PEU) micro- or nanowires freely suspended between two micropillars on a micro-structured silicon wafer substrate. An excellent shape-memory performance of the PEU microwires (diameter of 1.0±0.2 μm) becomes apparent (high strain fixity and recovery ratios) with this technique and the switching temperature could be adjusted by variation of the deformation temperature. A single PEU nanowire with a diameter of (98±27) nm exhibited an impressive maximum recovery stress of σmax=(33.3±0.1) MPa. Efficient indirect heating of thermally triggered shape-memory polymers could be realized by incorporation of polydopamine particles (PDAP) in polyurethanes. The PDAPs, which exhibit strong NIR absorption, high photothermal conversion efficiency, and photostability, can form hydrogen bonds with the polyurethane matrix