geotextiles, airbags, safety belts, reinforcements for composites, many types of medical implants, etc.). A paradigm has for long been that among technical artefacts [4] textiles are passive (no need for power to perform its function), which could be compared with items from other technical spheres such as computers, radios, or cars, that are regarded as active, i.e., needing power, electrical, or otherwise, to perform their function. The dichotomy passiveactive is often used in electronics [5,6] and control theory to classify components. Passive components [7] (conductors, chassis, resistors, etc.) are those that are not intended to impact any signal or energy transferred through it, whereas active ones (batteries, fans, storage device, transistors, diodes, integrated circuits, etc.) are there exactly for doing this. The smart textile community is at a meeting point between textiles and electronics and the distinction of active and passive as used in electronics is mixed with a general common-language one, where active means "doing something." Any mechanical impact on the surrounding, such as moving a mass spatially, is deemed to exert work, i.e., utilize energy. In this text we stipulate as active such artefacts that are able to move any masses, either of the artefact itself or outside of it. As more and more instances accumulate showing that also textile artefacts could be given this property, also textiles are entering into the domain of being regarded as active. In retrospect, there are some early examples of what today could be defined as active textiles. One such example is the Ventile fabric [8] from the 1940s that was used as a waterproof protecting layer. This fabric operated by the swelling ability of cotton yarn hindering water to penetrate beyond the amount used for the very swelling. However, it was not until the 1980s that textiles-especially garments-were "discovered" as a potential arena for enrichment by other kinds of technologies such as sensorics for measuring the wearer as well as monitoring the surrounding. These have interchangeably been denoted as smart textiles, [9] intelligent textiles, [10] or electronic textiles. [11] This "(re)discovery" of textiles as an interesting field for new technical developments is in parallel with the "(re)discovery" of paper, which, although started later moved at a faster pace and printed electronics, [12] paper electronics, [13] or smart papers [14] now have emerged as branches on their own. Both textiles and papers are polymeric, fiber-based, cheap, pliable, flexible, large area (semi) 2D materials that take part in everyday activities of humans and by this being ubiquitous ever present. Textiles and papers have their respective benefits; textiles for Smart textiles have been around for some decades. Even if interactivity is central to most definitions, the emphasis so far has been on the stimuli/ input side, comparatively little has been reported on the responsive/output part. This study discusses the actuating, mechanical, output side in what could be ...
Both the nonisothermal and isothermal crystallization kinetics under the influences of different shear conditions for poly(lactic acid) (PLA) were investigated by rheometry. The nucleation and growth of PLA spherulites during isothermal crystallization with different shear conditions were observed by polarized optical microscopy (POM). Shear-induced nucleation rate enhancements of PLA were studied on the basis of the prerequisite determination of the critical shear rates, for which the stretch of the longest chains (high molecular mass tails) of PLA would be expected. The transitions between different shear flow regimes for shear-induced crystallization of PLA at the temperature of 135 °C were determined by two characteristic Weissenberg numbers on the basis of reptation time and Rouse time for the high molecular mass tails, which were determined through combination of the discrete Maxwell relaxation time spectra of PLA at the reference temperature of 190 °C and the Arrhenius type of temperature dependence for the horizontal shift factor, aT . It was then found that the crystallization process of PLA was greatly enhanced by shear compared to the quiescent condition, and the crystallization kinetics could be accelerated by the increased shear rate and/or shear time. It was more interesting to find that there existed a critical shear time under a certain shear rate, and a further increase in the shear time did not lead to further acceleration of the crystallization kinetics. POM observation indicated that the acceleration of crystallization kinetics was obviously brought about by the enhanced nucleus density under the application of shear and the subsequent spherulitic growth rates kept about constant. Thus, a kinetic model based on directly relating the extra number of activated nuclei promoted by shear to the shear rate was further applied to well predict the effects of shear time on the shear-induced isothermal crystallization kinetics of PLA.
An ionic conducting membrane is an essential part in various electrochemical devices including ionic actuators. To miniaturize these devices, micropatterns of ionic conducting membrane are desired. Here, we present a novel type of ionogel that can be patterned using standard photolithography and soft imprinting lithography. The ionogel is prepared in situ by UV-initiated free-radical polymerization of thiol acrylate precursors in the presence of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The resultant ionogel is very flexible with a low Young's modulus (as low as 0.23 MPa) and shows a very high ionic conductivity (up to 2.4 × 10 S/cm with 75 wt % ionic liquid incorporated) and has a reactive surface due to the excess thiol groups. Micropatterns of ionogel are obtained by using the thiol acrylate ionogel solution as an ionic conducting photoresist with standard photolithography. Water, a solvent immiscible with ionic liquid, is used as the photoresist developer to avoid complete removal of ionic liquid from thin micropatterns of the ionogel. By taking advantage of the reactive surface of ionogels and the photopatternability, ionogels with complex three-dimensional microstructure are developed. The surface of the ionogels can also be easily patterned using UV-assisted soft imprinting lithography. This new type of ionogels may open up for building high-performance flexible electrochemical microdevices.
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