Synthesis of temperature and pH/CO2 responsive homopolymer bearing oligo(ethylene glycol) unit and N,N-diethylamino ethyl group and its solution property

A Temperature and pH Dual-Sensitive Multifunctional Polyurethane with Bacteria-Triggered Antibacterial Activity

An effective and practical antibacterial strategy is to design multifunctional and stimuli-responsive materials that exhibit antibacterial activity in response to bacterial triggers. In this study, because the metabolism of Staphylococcus aureus (S. aureus) can acidify the surrounding environment and pH level can affect the lower critical solution temperature of temperature/pH dual-sensitive polymers, a monomer containing a temperature-sensitive N-isopropyl amide derivative and pH-sensitive tertiary amine groups is first synthesized. Then, the monomer is copolymerized with a polyurethane chain, and partial tertiary amine groups are quaternized to obtain bactericidal activity. The modified polyurethane exhibits temperature/pH sensitivity, antibacterial adhesion activity, bactericidal activity, and good cytocompatibility. An in situ investigation of bacterial behavior and pH changes in the bacterial suspension during the process confirms that the temperature/pH dual-sensitive polyurethane successfully achieves antibacterial activity though the metabolic activity of S. aureus without external intervention. This design concept provides a new perspective for antibacterial material design.

Evaluation of renewable pH-responsive starch-based flocculant on treating and recycling of highly saline textile effluents

Herein, we report a novel renewable pH-responsive starch-based flocculant (CIAT-ST) via etherifying 2-chloro-4,6-isopropylamino-[1,3,5]-triazine (CIAT) onto the starch backbones for decontamination and reuse of highly saline effluents. The obtained CIAT-ST shows a unique pH-sensibility and reversibility in response to a subtle pH change due to a pH-controllable surface charge density of polymer chains. The level of residual CIAT-ST in the solution can be facilely monitored by using UV-vis detection. The dye flocculation performance of CIAT-ST was evaluated by using a batch experiment. The results exhibited that the dye removal was highly dependent on the solution pH (optimal pH was 2), the flocculation equilibrium can be achieved within 5 min, and the maximum flocculation capacity of CIAT-ST for K-2BP and KN-B5 were calculated to be 2452.6 ± 23.9 and 792.7 ± 14.1 mg/g, respectively. The multiple flocculation mechanisms, including charge neutralization, bridging and charge patching, may participate in the flocculation process. Adjustment in pH-mediated hydrophilicity-hydrophobicity switch of flocculant facilitates readily recovery and then sequentially reused three times while retaining satisfying flocculation efficiency. A significant contribution was also confirmed that the highly saline effluents after flocculation and sedimentation were reused in three successive dyeing processes without sacrificing fabric quality (ΔE* < 1) due to relatively low polymer residuals, and the efficiency of salt reuse for consecutive regeneration processes could be achieved above 85%. The present work could provide alternative thoughts for the reutilization of spent flocculant and clarified saline wastewater, which is also an efficient and sustainable strategy for textile wastewater management.

Thermoresponsive Polymers Based on Tertiary Amine Moieties

Thermoresponsive polymers exhibiting unique reversible phase transition properties in aqueous solution in response to temperature stimuli have been extensively investigated. In the past two decades, thermoresponsive polymers based on tertiary amine moieties have achieved considerable progress and become an important family of thermoresponsive polymers, including tertiary amine functionalized poly((meth)acrylamide)s, poly((meth)acrylate)s, poly(styrene)s, poly(vinyl alcohol)s, and poly(ethylene oxide)s, which exhibit lower critical solution temperature and/or upper critical solution temperature in water or aliphatic alcohols. Their phase transition behavior can be modulated by the solution pH and CO₂ due to the protonation of tertiary amine moieties in acidic condition and deprotonation in alkaline condition and the charged ammonium bicarbonate formed by the tertiary amine moieties and CO₂ . The aim of this review is to summarize the recent progress in the thermoresponsive polymers based on tertiary amine moieties.

Amphoteric starch derivatives as reusable flocculant for heavy-metal removal

A pH-responsive amphoteric starch derivative (PRAS) bearing dual functional groups (amino and carboxyl groups) was prepared through etherification of starch with 2-chloro-4,6-diglycino-[1,3,5]-triazine. PRAS exhibits a reversible pH-response property in aqueous solution. The attractive property of PRAS is that it could be used as an effective flocculant for heavy metal-ion (e.g. Cu(ii) and Zn(ii)) removal from wastewater by changing pH. The transition of hydrophobicity–hydrophilicity would produce shrinkage of the polymer matrix, facilitating the release of heavy-metal ions from the saturated flocculant. As an ideal flocculant PRAS displayed outstanding stability and reproducibility, whose remove rate for Cu(ii) and Zn(ii) remained at 93% and 91% after three flocculation/regeneration cycles.

A pH-responsive starch-based flocculants containing both cationic and anionic functional groups has been developed. The saturated flocculant can be facilely regenerated and separated from the solution by applying an external pH stimulus.

Oxygen and carbon dioxide dual gas-responsive homopolymers and diblock copolymers synthesized via RAFT polymerization

This article reports a new strategy to prepare homopolymers with CO₂ and O₂ responsiveness via the installation of CO₂- and O₂-responsive functionalities in the same repeated unit.

Triple-stimuli-responsive ferrocene-containing homopolymers by RAFT polymerization

This article presents a new type of well-defined ferrocene-containing homopolymer obtained from RAFT polymerization, showing pH/CO₂ and redox responsiveness.

CO2-responsive polymeric materials: synthesis, self-assembly, and functional applications

CO2 is an ideal trigger for switchable or stimuli-responsive materials because it is benign, inexpensive, green, abundant, and does not accumulate in the system. Many different CO2-responsive materials including polymers, latexes, solvents, solutes, gels, surfactants, and catalysts have been prepared. This review focuses on the preparation, self-assembly, and functional applications of CO2-responsive polymers. Detailed discussion is provided on the synthesis of CO2-responsive polymers, in particular using reversible deactivation radical polymerization (RDRP), formerly known as controlled/living radical polymerization (CLRP), a powerful technique for the preparation of well-defined (co)polymers with precise control over molecular weight distribution, chain-end functional groups, and polymer architectural design. Self-assembly in aqueous dispersed media is highlighted as well as emerging potential applications.

RAFT synthesis of triply responsive poly[N-[2-(dialkylamino)ethyl]acrylamide]s and their N-substitute determined response

The thermo- and pH/CO₂-responsive poly[N-[2-(dialkylamino)ethyl]acrylamide]s containing a polyacrylamide backbone but different N-substitutes of dialkylamine were synthesized and their solution properties were comparatively checked.

Dual thermo- and light-responsive dendron-jacketed homopolymers containing photoswitchable azobenzene groups via a macromonomer route

The novel dendron-jacketed homopolymer containing photoswitchable azobenzene groups and short oligo(ethylene glycol) (OEG) units was synthesized via a macromonomer route, which can exhibit interesting dual thermo- and light-responsive behaviours.

Self-assemblies of amphiphilic homopolymers: synthesis, morphology studies and biomedical applications

The need for a simplified access to supramolecular assemblies with enhanced tenability has led to the development of amphiphilic homopolymers (APHPs). This review highlights recent advances and future trends in APHP design, self-assembly, and biomedical applications.