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The network structure and reactivity of suitable restoration agent consisting of silane coupling agents (SCAs) of the brittle walls of a cultural heritage site located underground in a desert area in Egypt were investigated using 1H pulsed nuclear magnetic resonance (pulse NMR). It should possess both high coagulation strength and ductility to ensure that it can withstand an earthquake; it should also contain ethoxy rather than methoxy groups, which generate toxic methanol. The solidification rate for the SCA or oligomer with ethoxy groups was lower than those with methoxy groups; however, the final polycondensates showed the same relaxation time (hardness). The difference spectrum was developed newly to analyze the network structure combined higher strength and ductility. The distribution of crosslinking degree of such polycondensates was narrow, and the amount of lower crosslinking degree was small. On the other hand, the distribution was wide in the polycondensates with ductility but lower strength. From the compression tests of model sand solidified with the restoration agent for both methoxy and ethoxy types showed the superior properties combined higher strength and ductility. The pulse NMR experiment was useful for estimating the solidification rate and the network structure. [ABSTRACT FROM AUTHOR]

Responsiveness to stimuli is important in daily life: natural biological activity is governed by continuous stimulus responsiveness. The design of stimuli-responsive materials is required for the development of advanced sensing systems. Although fully controlled stimuli-responsive systems have been constructed in nature, artificial systems remain a challenge. Conventional stimuli-responsive materials show direct responsiveness to an applied stimulus (Stimulus 1), with structural changes in their molecules and organized states. This feature article focuses on cascading responses as a new concept for integrating stimuli-responsive material design. In cascading responses, an original stimulus (Stimulus 1) is converted into other stimuli (Stimulus 2, 3, ..., N) through successive conversions. Stimulus N provides the eventual output response. Integration of multiple stimuli-responsive materials is required to achieve cascading responses. Although cascade, domino, and tandem chemical reactions have been reported at the molecular level, they are not used for materials with higher organized structures. In this article, we introduce functional carriers and sensors based on cascading responses as model cases. The concept of cascading responses enables the achievement of transscale responsivity and sensitivity, which are not directly induced by the original stimulus or its responsive material, for the development of advanced dynamic functional materials. [ABSTRACT FROM AUTHOR]

Gas marbles are a new family of particle‐stabilized soft dispersed system with a soap bubble‐like air‐in‐water‐in‐air structure. Herein, stimulus‐responsive character is successfully introduced to a gas marble system for the first time using polymer particles carrying a poly(tertiary amine methacrylate) (pKa ≈7) steric stabilizer on their surfaces as a particulate stabilizer. The gas marbles exhibited long‐term stability when transferred onto the planar surface of liquid water, provided that the solution pH of the subphase is basic and neutral. In contrast, the use of acidic solutions led to immediate disintegration of the gas marbles, resulting in release of the inner gas. The critical minimum solution pH required for long‐term gas marble stability correlates closely with the known pKa value for the poly(tertiary amine methacrylate) stabilizer. It also demonstrates amphibious motions of the gas marbles. [ABSTRACT FROM AUTHOR]

To clarify the formation mechanism of front frame‐type morphology, the stringiness of crosslinked random copolymers of poly(n‐butyl acrylate‐acrylic acid) during a 180° peel test with a constant tensile rate was examined for various crosslinker contents and rates using a quartz adherend. Cohesive failure occurred for lower crosslinker content and rate, whereas interfacial failure with sawtooth‐type stringiness without a frame was observed for higher crosslinker content and rate. Front frame‐type stringiness was formed at the boundary of cohesive and interfacial failures. To clarify the formation mechanism, observation was conducted from the start of peel test until the equilibrium state. The sawtooth‐type stringiness with branches first formed at the tip. The adjoining branches were connected and the 2D frame was formed only on the adherend surface. The formed 2D frame developed toward the 3D walls and the front frame‐type was then completed. This is caused by the surface tension that acts to restrain the increase in the surface area. However, the surface area of the front frame‐type morphology was larger than the no frame‐type. The larger absorption of peeling stress by the formation of this morphology is expected to contribute to peel strength improvement. [ABSTRACT FROM AUTHOR]

Bubbles with polyhedral morphologies were fabricated using polymer plates as a stabilizer. Precise control of the shape and size of the bubbles could be performed by tuning the size ratio of the air bubble and plate, controlling the number of plates adsorbed to the bubble, and coalescence of multiple bubbles. [ABSTRACT FROM AUTHOR]