Guannan Ju

Bell‐Shaped Superhydrophilic–Superhydrophobic–Superhydrophilic Double Transformation on a pH‐Responsive Smart Surface

Superhydrophobic to neutral water droplets, superhydrophilic to acidic or basic. This double transition of surface wettability in response to a single stimulus - pH - is demonstrated for the first time. The smart surface is composed of a rough gold surface modified with a self-assembled monolayer (SAM) containing three thiols, HS(CH2 )11 CH3 , HS(CH2 )10 COOH, and HS(CH2 )11 NH2 . A ternary diagram is generated that describes wettability as a function of the SAM composition and the pH of the surrounding solution.

pH‐Responsive On‐Off Motion of a Superhydrophobic Boat: Towards the Design of a Minirobot

Combining chemical reactions and stimuli-responsive surfaces as clutch system, a functional cooperating minirobot with on-off locomotion that is responsive to pH changes is fabricated. Its locomotion can be switched on by changing pH value of the solution from 1 to 13, turned off by adjusting the pH back to acidic, and restarted by transforming the solution to basic.

Converting Chemical Energy Into Electricity through a Functionally Cooperating Device with Diving–Surfacing Cycles

A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity.

Magnetically directed clean-up of underwater oil spills through a functionally integrated device

To handle serious underwater oil spills, we have designed a functionally integrated device which can continuously clean up spilled oil underwater or on the waters surface in a directional manner, guided by a magnetic field, collecting the oil into the interior of the device and recycling it. The collecting efficiency is higher than 90%.

Supramolecular Assembly of Macroscopic Building Blocks Through Self-Propelled Locomotion by Dissipating Chemical Energy

Chemical energy supplied by the catalytic decomposition of H2O2 is introduced into macroscopic building blocks, which self-propel, interact with each other, and finally assemble into ordered and advanced structures. The geometry is highly dependent on the way that the catalyst is loaded. The integration of catalyst and building block provides assembling component as well as its energy of motion.

A facile method to immobilize cucurbituril on surfaces through photocrosslinking with azido groups

We develop a facile method to immobilize cucurbituril on silicon substrates through photochemical reaction with azido groups. Combining photolithography and the competitive molecular recognition between CB[7] and acridine orange base or 1-adamantanecarboxylic acid, a patterned surface with reversible fluorescence emission can be obtained.

Biomimicking of a Swim Bladder and Its Application as a Mini-Generator

A model fish with a man-made swim bladder achieves fast vertical motions based on density adjustments in a pressure-responsive way. When exposed to a magnetic field, a mini-generator is achieved by harvesting energy from the environment, working with pressure differences in the blood-pressure range and at the frequency of a beating heart.

Self-Correction Strategy for Precise, Massive, and Parallel Macroscopic Supramolecular Assembly

Macroscopic supramolecular assembly (MSA) represents a new advancement in supramolecular chemistry involving building blocks with sizes beyond tens of micrometers associating through noncovalent interactions. MSA is established as a unique method to fabricate supramolecularly assembled materials by shortening the length scale between bulk materials and building blocks. However, improving the precise alignment during assembly to form orderly assembled structures remains a challenge. Although the pretreatment of building blocks can ameliorate order to a certain degree, defects or mismatching still exists, which limits the practical applications of MSA. Therefore, an iterative poststrategy is proposed, where self-correction based on dynamic assembly/disassembly is applied to achieve precise, massive, and parallel assembly. The self-correction process consists of two key steps: the identification of poorly ordered structures and the selective correction of these structures. This study develops a diffusion-kinetics-dependent disassembly to well identify the poorly aligned structures and correct these structures through iterations of disassembly/reassembly in a programmed fashion. Finally, a massive and parallel assembly of 100 precise dimers over eight iteration cycles is achieved, thus providing a powerful solution to the problem of processing insensitivity to errors in self-assembly-related methods.

Chemical and Equipment-Free Strategy To Fabricate Water/Oil Separating Materials for Emergent Oil Spill Accidents

Oil spill accidents normally have two important features when considering practical cleanup strategies: (1) unexpected occurrence in any situations possibly without specific equipment and chemicals; (2) emergency to be cleaned to minimize the influences on ecosystems. To address these two practical problems regarding removal of spilt oil, we have proposed an in situ, rapid, and facile candle-soot strategy to fabricate water/oil separating materials based on superhydrophobicity/superoleophilicity. The one-step fabrication method is independent of any chemicals or equipment and can be ready for use through short smoking processes within 5 min by using raw materials available in daily life such as textiles. The as-prepared materials perform good durability for repeated separation test and high recovery rate of various oils from water/oil mixtures. This strategy provides possibility of rapid response to sudden oil spill accidents, especially in cases without any equipment or chemicals and in poor countries/areas those could hardly afford transportation and storage of expensive separating materials.

Elasticity‐Dependent Fast Underwater Adhesion Demonstrated by Macroscopic Supramolecular Assembly

Macroscopic supramolecular assembly (MSA) is a recent development in supramolecular chemistry to associate visible building blocks through non-covalent interactions in a multivalent manner. Although various substrates (e.g. hydrogels, rigid materials) have been used, a general design rule of building blocks in MSA systems and interpretation of the assembly mechanism are lacking and are required. Herein we design three model systems with varied elastic modulus and correlated the MSA probability with the elasticity. Based on the effects of substrate deformability on multivalency, we have proposed an elastic-modulus-dependent rule that building blocks below a critical modulus of 2.5 MPa can achieve MSA for the used host/guest system. Moreover, this MSA rule applies well to the design of materials for fast underwater adhesion: Soft substrates (0.5 MPa) can achieve underwater adhesion within 10 s with one order of magnitude higher strength than that of rigid substrates (2.5 MPa).