Multi Stimuli-Responsive Aggregation-Induced Emission Active Polymer Platform Based on Tetraphenylethylene-Appended Maleic Anhydride Terpolymers

Multi stimuli-responsive aggregation-induced emission (AIE) active polymers have great application prospects in high-tech innovations. Herein, three types of tetraphenylethylene (TPE)-containing monomers were synthesized and utilized in preparing TPE-appended maleic anhydride terpolymers. After hydrolysis, the produced TPE-appended maleic acid terpolymers have identical linear charge densities but different "primary" structures, which created widely varied microenvironments around the carboxylate and TPE groups. Benefiting from the synergistic interaction of the TPE moiety and the terpolymer conformation change, the TPE-appended maleic acid terpolymers exhibited fluorescence changes in response to multi stimuli, including pH, ionic strength, Ca²⁺, and bovine serum albumin. On both the "signaling" and the "stimuli acceptor" sides, the multi stimuli-responsive fluorescence behavior was influenced markedly by the terpolymer primary structure. The fundamental insights gained in the present work are important for developing an efficient and versatile stimuli-responsive AIE-active polymer platform for chemo-sensing, bioimaging, and so on.

Light-dimerization telechelic alginate-based amphiphiles reinforced Pickering emulsion for 3D printing

Functional Pickering emulsions that depend on the interparticle interactions hold promise for building template materials. A novel coumarin-grafting alginate-based amphiphilic telechelic macromolecules (ATMs) undergoing photo-dimerization enhanced particle-particle interactions and changed the self-assembly behavior in solutions. The influence of self-organization of polymeric particles on the droplet size, microtopography, interfacial adsorption and viscoelasticity of Pickering emulsions were further determined by multi-scale methodology. Results showed that stronger attractive interparticle interactions of ATMs (post-UV) endowed Pickering emulsion with small droplet size (16.8 μm), low interfacial tension (9.31 mN/m), thick interfacial film, high interfacial viscoelasticity and adsorption mass, and well stability. The high yield stress, outstanding extrudability (n₁ < 1), high structure maintainability, and well shape retention ability, makes them ideal inks for direct 3D printing without any additions. The ATMs provides an increased capacity to produce stable Pickering emulsions with tailoring their interfacial performances and, providing a platform for fabricating and developing alginate-based Pickering emulsion-templated materials.

Effect of chain microstructure on self-assembly and emulsification of amphiphilic poly(acrylic acid)-polystyrene copolymers

In this study, a series of random copolymer poly(acrylic acid-co-styrene) (P(AA-co-St)) and block copolymer poly(acrylic acid)-b-polystyrene (PAA-b-PSt) with similar chemical composition but different chain microstructure were synthesized. The self-assembly behavior of random and block copolymers in selective solvent was investigated, and the structural evaluation of random and block copolymers micelles was carried out by transmission electron microscopy (TEM), dynamic light scattering (DLS) measurement, and X-ray photoelectron spectroscopy (XPS). Moreover, together with experimental characterization, the theoretical method dissipative particle dynamics (DPD) approach was applied to investigate the morphological structures of micelles composed from random and block copolymers. Results revealed that the structure of polymeric micelles is significantly affected by the distribution sequence of hydrophilic and hydrophobic monomers in copolymer chains. Furthermore, polymeric micelles based on P(AA-co-St) and PAA-b-PSt with about 50 mol% hydrophilic composition were chosen as the model to investigate the influence of micellar structure on emulsifying performance. For PAA-b-PSt micelles (B48), stable water-in-oil (w/o) emulsions could only obtained when the pH values were lower than 5. As a comparison, the P(AA-co-St) micelles (R49) had an excellent emulsification performance at 4-10 pH, and the pH-induced phase inversion derived from obtained emulsions observed at pH higher than 6. Preliminary results confirm that the micellar structure controlled by chain microstructure plays an important role in the interface behavior of polymer micelles. Compared with PAA-b-PSt micelles, P(AA-co-St) micelles have better interfacial performance and are more tailorable and controllable; thus they can be used as a model for further study of polymeric particulate emulsifiers. This paper provides new insight into the principles governing extremely high emulsifying efficiency of polymeric particulate emulsifiers and pH-responsive properties of the formed emulsions.

Tuning Amphiphilicity of Particles for Controllable Pickering Emulsion

Pickering emulsions with the use of particles as emulsifiers have been extensively used in scientific research and industrial production due to their edge in biocompatibility and stability compared with traditional emulsions. The control over Pickering emulsion stability and type plays a significant role in these applications. Among the present methods to build controllable Pickering emulsions, tuning the amphiphilicity of particles is comparatively effective and has attracted enormous attention. In this review, we highlight some recent advances in tuning the amphiphilicity of particles for controlling the stability and type of Pickering emulsions. The amphiphilicity of three types of particles including rigid particles, soft particles, and Janus particles are tailored by means of different mechanisms and discussed here in detail. The stabilization-destabilization interconversion and phase inversion of Pickering emulsions have been successfully achieved by changing the surface properties of these particles. This article provides a comprehensive review of controllable Pickering emulsions, which is expected to stimulate inspiration for designing and preparing novel Pickering emulsions, and ultimately directing the preparation of functional materials.

One-step formation of multiple Pickering emulsions stabilized by self-assembled poly(dodecyl acrylate-co-acrylic acid) nanoparticles

In this study, a one-step generation of stable multiple Pickering emulsions using pH-responsive polymeric nanoparticles as the only emulsifier was reported. The polymeric nanoparticles were self-assembled from an amphiphilic random copolymer poly(dodecyl acrylate-co-acrylic acid) (PDAA), and the effect of the copolymer content on the size and morphology of PDAA nanoparticles was determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The emulsification study of PDAA nanoparticles revealed that multiple Pickering emulsions could be generated through a one-step phase inversion process by using PDAA nanoparticles as the stabilizer. Moreover, the emulsification performance of PDAA nanoparticles at different pH values demonstrated that multiple emulsions with long-time stability could only be stabilized by PDAA nanoparticles at pH 5.5, indicating that the surface wettability of PDAA nanoparticles plays a crucial role in determining the type and stability of the prepared Pickering emulsions. Additionally, the polarity of oil does not affect the emulsification performance of PDAA nanoparticles, and a wide range of oils could be used as the oil phase to prepare multiple emulsions. These results demonstrated that multiple Pickering emulsions could be generated via the one-step emulsification process using self-assembled polymeric nanoparticles as the stabilizer, and the prepared multiple emulsions have promising potential to be applied in the cosmetic, medical, and food industries.

Closed-cell and open-cell porous polymers from ionomer-stabilized high internal phase emulsions

We firstly present a strategy that enables fabrication of both closed-cell and open-cell porous polymers (polyHIPEs) from high internal phase emulsions (HIPEs) stabilized with an ionomer.