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Diabetic foot ulcers (DFU) remain a very considerable health care burden, and their treatment is difficult. Hydrogel-based wound dressings are appealing to provide an optimal environment for wound repair. However, the currently available hydrogel dressings still need surgical or mechanical debridement from the wound, causing reinjury of the newly formed tissues, wound infection, delayed healing time, and personal suffering. Additionally, to meet people's increasing demand, hydrogel wound dressings with improved performance and multifunctionality are urgently required. Here, a new multifunctional supramolecular hydrogel for on-demand dissolvable diabetic foot wound dressings is designed and constructed. Based on multihydrogen bonds between hydrophilic polymers, the resultant supramolecular hydrogels present controlled and excellent properties, such as good transparency, antibacterial ability, conductive, and self-healing properties. Thus, the supramolecular hydrogels improve the new tissue formation and provide a significant therapeutic effect on DFU by inducing angiogenesis, enhancing collagen deposition, preventing bacterial infection, and controlling wound infection. Remarkably, the resultant hydrogels also exhibit stimuli-responsive ability, which renders its capability to be dissolved on-demand, allowing for a facile DFU dressing removal. This multifunctional supramolecular hydrogel may provide a novel concept in the design of on-demand dissolvable wound dressings.

Self-assembly of asymmetric block copolymers (BCPs) around active pore edges has emerged as an important strategy to produce smart membranes with tunable pathways for solute transport. However, thus far, it is still challenging to manipulate pore shape and functionality for directional transformation under external stimuli. Here, a versatile strategy by mesoscale simulations to design stimuli-responsive pores with various edge decorations in hybrid membranes is reported. Dopant BCPs are used as decorators to stabilize pore edges and extend their function in reconfiguring pores in response to repeated membrane stretching/shrinking caused by external stimuli. The decoration morphologies are predictable since the assemblies of dopant BCPs around pore edges are closely related to their self-assemblies in solution. The coassembly between different BCPs in the hybrid membrane for the control of pore morphology is featured, and the parameter settings, including block incompatibility and molecular architecture for the construction of a specific pore, are determined. Results show that harnessed dopant BCPs in the hybrid membrane can enhance pore formation and induce directional pore shape and functionality transformation. Diversified pore decorations exhibit potential that can be further explored in selective solute transport and the design of stimuli-responsive smart nanodevices.

Surfaces coated with polyzwitterions are most well-known for their ability to resist protein adsorption. In this article, a surface-attached hydrophobically modified poly(carboxybetaine) is presented. When protonated by changes of the pH of the surrounding medium, this protein-repellent polyzwitterion switches to a polycationic state in which it is antimicrobially active and protein-adhesive. The pH range in which these two states exist are recorded by zeta potential measurements. Adsorption studies at different pH values (monitored by surface plasmon resonance spectroscopy) confirm that the adhesion of protein is pH dependent and reversible, that is, protein can be released upon a pH change from pH 3 to pH 7.4. At physiological pH, the poly(carboxyzwitterion) is antimicrobially active, presumably because it becomes protonated by bacterial metabolites during the antimicrobial activity assay. Stability studies confirm that the here presented material is storage-stable, yet hydrolyses after longer incubation in aqueous media.

Known for their adaptability to surroundings, capability of transport control of molecules, or the ability of converting one type of energy to another as a result of external or internal stimuli, responsive polymers play a significant role in advancing scientific discoveries that may lead to an array of diverge applications. This review outlines recent advances in the developments of selected commodity polymers equipped with stimuli-responsiveness to temperature, pH, ionic strength, enzyme or glucose levels, carbon dioxide, water, redox agents, electromagnetic radiation, or electric and magnetic fields. Utilized diverse applications ranging from drug delivery to biosensing, dynamic structural components to color-changing coatings, this review focuses on commodity acrylics, epoxies, esters, carbonates, urethanes, and siloxane-based polymers containing responsive elements built into their architecture. In the context of stimuli-responsive chemistries, current technological advances as well as a critical outline of future opportunities and applications are also tackled.

Stimuli-responsive polymers undergo changes under different environmental conditions. Among them, phenylboronic acid (PBA) containing polymers (PBA-polymers) are unique, because they can selectively react with diols to generate borates that are sensitive to pH, sugars, and H2 O2 , and can be effectively used to synthesize smart drug carriers and self-healing hydrogels. Recently, multifunctional PBA-polymers (MF-PBA-polymers) have been developed using multicomponent reactions (MCRs) to introduce PBA groups into polymer structures. These MF-PBA-polymers have features similar to those of traditional PBA-polymers; moreover, they exhibit additional properties, such as fluorescence, antimicrobial activity, and antioxidant capability, when different MCRs are used. In this mini review, the preparation of these MF-PBA-polymers are summarized and the new properties/functions that have been introduced into these polymers using different MCRs are discussed. The uses of these MF-PBA-polymers as fluorescent cell anticoagulants, drug carriers, and gelators of functional self-healing hydrogels have been discussed. Additionally, the challenges encountered during their preparation are discussed and also the future developments in this field are touched upon.

Ruthenium-containing polymers (RCPs) are a type of functional metallopolymer. Stimuli-responsive RCPs in which the responsive behaviors derive from the structure variation of Ru complexes are reviewed in this Feature Article, with particular focus on redox responsive RCPs and photoresponsive RCPs. On the basis of the recent progress, the response principle, syntheses, structures, properties, applications, and remaining challenges of such stimuli-responsive RCPs are discussed.

Different from the conventional irreversible covalent conjugations, a simple and efficient dynamic Schiff base covalent assembly is developed to construct the stable and smart dipeptide-protein hydrogels under mild conditions. Diphenylalanine-hemoglobin hydrogel is chosen to investigate the gelation formation process and mechanism. It is found that such assembled dipeptide-protein hydrogels are sensitive to pH variation, and simultaneously the proteins can be released without changing the native secondary structures from the gels. Furthermore, these adaptive hydrogels can encapsulate a series of small molecules, multicomponent proteins, and functional nanoparticles. These versatile hydrogels may find a great potential in bioapplications.

For most stimuli-responsive polymer materials (SRPMs), such as polymer gels, micelles, and brushes, the responsive mechanism is based on the solubility or compatibility with liquid media. That basis always results in distorting or collapsing the material's appearance and relies on external liquids. Here, a novel kind of SRPMs is proposed. Unlike most SRPMs, liquid is stored within special domains rather than expelled, so it is deforming-free and relying on no external liquid, which is referred to as self-storage SRPMs (SS-SRPMs). The facile and universal route to fabricate SS-SRPMs allows for another novel family of SRPMs. Furthermore, it is validated that SS-SRPMs can drastically respond to outside temperature like switchers, especially for optical and electrochemical responses. Those features hold prospects for applications in functional devices, such as smart optical lenses or anti-self-discharge electrolytes for energy devices.

Stimuli-responsive poly(N-isopropylacrylamide) nanogel with covalently labeled rhodamine B urea derivatives (P(NIPAM-co-RhBUA)) is utilized as a sensitive fluorescent probe for Cr(3+) in aqueous solution, and its thermo-induced tunable detection capacity is investigated. At 20 °C, non-fluorescent nanogel can selectively bind with Cr(3+) over some other metal ions, leading to prominent fluorescence OFF-ON switching due to the recognition of RhBUA with Cr(3+) . Upon heating above the phase transition temperature, enhanced fluorescence intensity is observed (≈61-fold increase at 45 °C) for the nanogel in the presence of Cr(3+) , accompanied with an improved detection sensitivity, which suggest that hydrophobic microenvironment generated in the collapsed nanogel plays an active role for their detection performance.

Multistimuli-responsive shape-memory polymers are highly desirable in various applications, and numerous modes have been developed in recent years. However, most of them need to reprogram before they are ready to respond to another stimulus while one is triggered. Here, a new strategy is developed to achieve dual-stimuli-responsive triple-shape memory with non-overlapping effect in one programming cycle. Here, a series of poly(l-lactide)-poly(tetramethylene oxide) glycol copolymers (PLA-PTMEG-A) is prepared by selected dangling photoresponsive anthracene moieties on the crystalline PTMEG backbone. The architectures of the copolymers are well-controlled in order to keep a good balance between the crystallinity of the soft segment and the mobility of the anthracene moieties. Thus, PLA-PTMEG-A's can respond to heat and light with non-overlapping effect. The thermally-induced shape-memory effect (TSME) is realized by the crystallization–melting transition of PTMEG soft segments, while the light-induced shape-memory effect (LSME) is achieved by the reversible photodimerization of anthracene groups. In view of the non-overlapping effect of TSME and LSME in the copolymers, a triple-shape-memory effect triggered by dual-stimuli is realized in one programming and recovery cycle.

This review documents the advances in stimuli-responsive water-soluble fullerene (C(60)) polymeric systems. Stimuli-responsive polymers, when grafted onto C(60) impart "smart" and "responsive" characteristics, and these novel materials adopt various morphologies when subjected to external stimuli, such as pH, temperature, and salt. Various synthetic approaches for producing C(60)-polymers are outlined and discussed. The responsive behavior, water solubility, and self-assembly characteristics of these C(60)-polymers make them attractive for applications such as drug delivery, temperature sensors, and personal care.

A novel functionalised poly(l-vinylpyrrolidin-2-one) (PVP) derivative, carrying a pre-detennined amount of 2-(2-pyridinyldithio)thylamine moieties as side substituents, P(VP-co-VP-SS-Py), has been prepared from carboxylated VP copolymers, in turn obtained by copolyinerising 1-vinyl-pyrrolidin-2-one with 3,3-di-(ethoxycart>onyl)-l-vinylpytrolidin-2-one in the presence of radical initiators. Using reaction solvents acting in the mean time as chain transfer agents could control its molecular weight. P(VP-co-VP-SS-Py) proved to be extremely reactive towards exchange reactions with molecules containing mercapto functions, including bioactive peptides. The exchange derivative with reduced glutathione, chosen as a model compound, was easily prepared.

Progress in the development of a redox-driven macromolecular motor and the characterization of its redox-mechanical cycle using electrochemical AFM-based single-molecule force spectroscopy (SMFS) is described. The elasticities of individual neutral and oxidized poly(ferrocenyldimethylsilane) (PFS) macromolecules were reversibly controlled in situ by adjusting the potential in electrochemical SMFS experiments. For the operating cycle of one individual PFS-based molecular motor, an output of 3.4 × 10-19 J and an efficiency of 5% have been estimated.

A highly asymmetric P2VP 58 -PAA 924 -PBMA 48 double hydrophilic block terpolymer exhibits a rich phase behavior as a function of pH. In acidic media (pH 1) three compartment micelles with a positively charged outer coronas are formed. At high pH, the above structure is transformed into a three-dimensional transient network constituted of hydrophobic domains interconnected with negatively charged bridging chains (PAA chains). At even higher pH (14) the network is disrupted and finally exhibits a closed loop sol-gel-sol behavior.

Aggregation-induced emission luminogens (AIEgens) have become an emerging field since the concept of AIE was proposed in 2001. Recently, AIEgens have attracted considerable attention due to their abnormal non-emissive fluorescent behavior in solution but strongly emissive behavior in the aggregate state. By utilizing the inherent hydrophobicity, AIEgens can be used to monitor the crystal formation and dewetting behavior in the self-assembly process. More importantly, some stimuli-responsive AIE-active surfaces have been successfully fabricated. In this perspective review, we outline the advances of surface wettability of AIEgens and its applications.

The combination of dendritic and linear polymeric structures in the same macromolecule opens up new possibilities for the design of block copolymers and for applications of functional polymers that have self-assembly properties. There are three main strategies for the synthesis of linear-dendritic block copolymers (LDBCs) and, in particular, the emergence of click chemistry has made the coupling of preformed blocks one of the most efficient ways of obtaining libraries of LDBCs. In these materials, the periphery of the dendron can be precisely functionalised to obtain functional LDBCs with self-assembly properties of interest in different technological areas. The incorporation of stimuli-responsive moieties gives rise to smart materials that are generally processed as self-assemblies of amphiphilic LDBCs with a morphology that can be controlled by an external stimulus. Particular emphasis is placed on light-responsive LDBCs. Furthermore, a brief review of the biomedical or materials science applications of LDBCs is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim., Financial support from the Spanish (MINECO) project MAT2011–27978-C02–01, Fondo Europeo de Desarrollo Regional (FEDER), Gobierno de Aragón, and Fondo Social Europeo is gratefully acknowledged.

The use of the molecular imprinting technique to produce polymers with high specificity for a given "molecular template" has undergone a rapid and expansive evolution since the inception of the idea over half a century ago. It was only a matter of time before the seemingly inevitable "marriage" of this concept with another modern research obsession, the generation of "smart" polymers, capable of reacting quickly, accurately and reproducibly to changes in their environment. Many advances have since been made, concerning the quality and diversity of these systems and polymers responsive to temperature, pH and a host of other environmental cues now exist. This article provides a succinct overview of the process and outcomes of "smart" molecular imprinting, followed by a detailed assessment of recent developments and applications in such field.