Biobased Magnetic Microspheres Containing Aldehyde Groups: Constructed by Vanillin-Derived Polymethacrylate/Fe₃O₄ and Recycled in Adsorbing Amine

This contribution reports a novel category of sustainable aldehyde-containing magnetic microspheres (ACMMs) prepared through suspension polymerization. For preparing the ACMMs, lignin-derived vanillin methacrylate (VMA) was used as biobased monomer, while methacrylated-Fe₃O₄ NPs were used as magnetic supplier. The resulting microspheres were proved to have remarkable magnetic property and adsorption capacity toward paraanisidine, which was employed as a representative of amines. The maximum adsorption was found to be up to 433 mg/g (559 mg/g in theory). Also noticeably, the adsorption was realized by forming a reversible Schiff base under mild conditions. Desorption processes were performed conveniently, proving that the ACMMs can be easily recycled. This work demonstrates the remarkable potentials of ACMMs to be used as scavenger resins in absorbing amines. Also worthy to be highlighted is that the abundant aldehyde groups enable the microspheres to be a promising platform for further preparing functional polymers by employing the Schiff base structure as linking parts, e.g. as biomaterials for immobilizing enzymes

High Performance Natural Rubber Composites with Well-Organized Interconnected Graphene Networks for Strain-Sensing Application

High-concentration reduced graphene oxide (RGO) solution was produced using gelatin (Gel) as the stabilizer and subreductant and hydrazine hydrate (HHA) as the main reductant. The Gel-HHA-RGO nanosheets exhibited excellent colloidal dispersibility and stability in alkaline condition. The Gel-HHA-RGO filled natural rubber (NR) composites were prepared by water-based solution casting. Well-organized interconnected RGO networks were constructed throughout the NR matrix, which played an important role in determining the properties of composites. The tensile modulus and dynamic storage modulus were improved by several orders of magnitude with increasing RGO content. Meanwhile, a dramatic increase in electrical conductivity with a low percolation threshold of 0.21 vol % was perceived. Strain-sensing tests revealed that the RGO/NR composites exhibited outstanding strain sensitivity and repeatability, which could be used to detect the cyclic movements of human joints. The results are promising in the rubber industry to guide the fabrication of highly sensitive and stretchable strain sensors for engineering application

Circularly Polarized Fluorescence Energy Transfer for Constructing Multicolor Circularly Polarized Luminescence Films with Controllable Handedness

Utilizing achiral fluorophores to fabricate circularly polarized luminescence (CPL) materials is of significant importance in both fundamental research and practical applications; chirality transfer has become an indispensable process in routine efforts reported so far. However, this may restrict or even become a bottleneck in further advancing CPL materials starting from achiral fluorophores. Inspired by biological light-harvesting architectural systems, we attempt to establish a new strategy, i.e., circularly polarized fluorescence energy transfer (CPF-ET) to explore multicolor CPL films in the absence of chirality transfer. CPL has been successfully realized through both radiative energy transfer and nonradiative energy transfer. The material systems consist of chiral fluorescent helical polyacetylene working as a circularly fluorescence polarized energy donor and achiral fluorophores as an energy acceptor. Achiral acceptors absorb circularly polarized fluorescence energy from the donor and hence emit the corresponding CPL; accordingly, chirality transfer is no longer an indispensable condition, and the sense of the CPL emission of the achiral fluorophores is controlled by the chiral fluorescent polymer. Moreover, multicolor CPL films can be simply prepared by employing varying achiral fluorophores. This work provides a facile and versatile platform for achieving CPL by taking advantage of achiral fluorophores

Biobased, Porous Poly(high internal phase emulsions): Prepared from Biomass-Derived Vanillin and Laurinol and Applied as an Oil Adsorbent

This contribution reports a novel type of biobased, porous, functional material [poly­(high internal phase emulsions), polyHIPEs] prepared from vanillin and laurinol derivatives. The polyHIPEs demonstrate high porosity (90%), low density (0.0935 g/cm3), and high specific surface area (38.6 m2/g). Owing to the multilevel pore structures (cell, window, and skeleton pores) and the chemical compositions, the polyHIPEs demonstrate suprahydrophobicity, with a water contact angle exceeding 160°, and excellent lipophilicity. The polyHIPEs are further explored as an oil adsorbent. The oil adsorption capacity increases upon increasing the water–oil ratio in the recipe for forming HIPEs and increases up to 40.9 g/g toward chloroform. The recycling use experiments prove that the materials’ oil adsorption ability can be well-maintained at least 10 times. The materials also demonstrate rapid oil adsorption capability. The polyHIPEs’ advantages, i.e., being derived from biomass and showing high oil-adsorption capacity and satisfactory recycling usability, endow them with promising potential as sustainable oil adsorbents

Biobased, Porous Poly(high internal phase emulsions): Prepared from Biomass-Derived Vanillin and Laurinol and Applied as an Oil Adsorbent

This contribution reports a novel type of biobased, porous, functional material [poly­(high internal phase emulsions), polyHIPEs] prepared from vanillin and laurinol derivatives. The polyHIPEs demonstrate high porosity (90%), low density (0.0935 g/cm3), and high specific surface area (38.6 m2/g). Owing to the multilevel pore structures (cell, window, and skeleton pores) and the chemical compositions, the polyHIPEs demonstrate suprahydrophobicity, with a water contact angle exceeding 160°, and excellent lipophilicity. The polyHIPEs are further explored as an oil adsorbent. The oil adsorption capacity increases upon increasing the water–oil ratio in the recipe for forming HIPEs and increases up to 40.9 g/g toward chloroform. The recycling use experiments prove that the materials’ oil adsorption ability can be well-maintained at least 10 times. The materials also demonstrate rapid oil adsorption capability. The polyHIPEs’ advantages, i.e., being derived from biomass and showing high oil-adsorption capacity and satisfactory recycling usability, endow them with promising potential as sustainable oil adsorbents

Chiroptical Elastomer Film Constructed by Chiral Helical Substituted Polyacetylene and Polydimethylsiloxane: Multiple Stimuli Responsivity and Chiral Amplification

Chiral and circularly polarized luminescence (CPL) materials with multiple stimuli responses have become a focus of attention. Meanwhile, elastomers have found substantial applications in a wide variety of fields. However, how to design and construct chiral elastomers, in particular CPL-active elastomers, still remains an academic challenge. In the present study, chiral helical substituted polyacetylene is chemically bonded with polydimethylsiloxane (PDMS) by hydrosilylation to form a chiroptically active elastomer. A CPL-active film was further fabricated by adding achiral fluorophores. Compared with the corresponding chiral helical polymer, the chiral films show much enhanced thermal stability in terms of chiroptical properties. The films also demonstrate reversible tunability in optical activity and CPL property when being subjected to a stretching–restoring process and exposed to a solvent like toluene. Further, noticeable chiral amplification is observed when the chiral PDMS film is superimposed with a pure PDMS film. This interesting finding is proposed to be due to the photoreflectivity of PDMS. This study provides an alternative strategy to exploit novel CPL-active elastomer materials with multiple stimuli responsivity and tunability, which may open up new opportunities for developing novel chiroptical devices

Aggregation-Induced Emissive Silicone Elastomer with Multiple Stimuli Responsiveness

Stable and highly efficient fluorescent silicone elastomers have attracted tremendous attention. In this contribution, a series of fluorescent silicone elastomers are facilely fabricated by combining aggregation-induced emission (AIE)-active polymers with a silicone matrix. The investigated AIE-active macromolecules are synthesized by reversible addition–fragmentation chain-transfer polymerization of vinyl monomers containing a tetraphenylethylene pendant. Detailed experimental characterizations demonstrate that macromolecular fluorescent compounds have good dispersibility and leaching resistance in silicone elastomers. Especially, the fluorescence properties of the silicone elastomers can be modulated by changing the molecular weight or aggregation state of the fluorescent macromolecules. Moreover, the prepared fluorescent silicone films show multiple stimulus responsiveness to strain, temperature, and organic solvents. The present work provides a simple and universal strategy toward fluorescent silicone elastomers for both scientific research and future practical applications

Polylactide-Based Chiral Porous Monolithic Materials Prepared Using the High Internal Phase Emulsion Template Method for Enantioselective Release

Polylactide [PLA, two enantiomers: poly­(l-lactide) (PLLA) and poly­(d-lactide) (PDLA)] has been widely applied as biomaterials because of its biocompatibility, biodegradability, and good mechanical capacity. However, the chirality of PLA materials has not been intensively explored yet. In the present study, chiral porous poly­(high internal-phase emulsion)­s (polyHIPEs) derived from enantiopure PLAs were successfully prepared via a HIPE template method. The resulting polyHIPEs show optical activity. More interestingly, the polyHIPEs demonstrate enantioselective release capacity, using cinchona alkaloid and naproxen as the model chiral drugs. Notably, PLLA-based polyHIPE shows enantioselectivity in both the drug-loading step and drug-releasing step, while PDLA-based polyHIPE fails. The interesting finding is essentially different from other chiral polymer materials reported earlier. The cytotoxicity test demonstrates that all the three types of polyHIPEs, PLLA-, PDLA-, and PDLLA-based polyHIPE show biocompatibility; however, their different chirality exerts varying effects on cell growth. Accordingly, special attention should be devoted to the chirality of PLA when used as biomaterials

pH-Sensitive Chiral Hydrogels Consisting of Poly(<i>N</i>‑acryloyl‑l‑alanine) and β‑Cyclodextrin: Preparation and Enantiodifferentiating Adsorption and Release Ability

Both chiral hydrogels and pH-sensitive hydrogels have received considerable attention in recent years. In the present study, we combined the two intriguing concepts, i.e., chirality and pH sensitivity, in one single hydrogel. Such hydrogels were prepared via free radical copolymerization using chiral <i>N</i>-acryloyl-l-alanine (NAA) as monomer, the inclusion complex of glycidyl methacrylate (GMA) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as comonomer, <i>N</i>,<i>N</i>′-methylenebis­(acrylamide) as cross-linking agent, and K₂S₂O₈ as initiator. The hydrogels were successfully obtained and exhibited remarkable swelling in water and pH responsivity. The hydrogels were characterized by circular dichroism and UV–vis absorption spectroscopies, demonstrating the optical activity of the hydrogels. The hydrogels performed chiral recognition and enantiodifferentiating release abilities toward proline enantiomers, in which l-proline was preferentially adsorbed whereas d-proline was preferentially released. The present study established a platform for preparing versatile, in particular, optically active hydrogels. Noticeably, the hydrogels are expected to find practical applications as novel materials for chiral drugs delivery

Biomass Vanillin-Derived Polymeric Microspheres Containing Functional Aldehyde Groups: Preparation, Characterization, and Application as Adsorbent

The contribution reports the first polymeric microspheres derived from a biomass, vanillin. It reacted with methacryloyl chloride, providing monomer vanillin methacrylate (VMA), which underwent suspension polymerization in aqueous media and yielded microspheres in high yield (>90 wt %). By controlling the N₂ bubbling mode and by optimizing the cosolvent for dissolving the solid monomer, the microspheres were endowed with surface pores, demonstrated by SEM images and mercury intrusion porosimetry measurement. Taking advantage of the reactive aldehyde groups, the microspheres further reacted with glycine, thereby leading to a novel type of Schiff-base chelating material. The functionalized microspheres demonstrated remarkable adsorption toward Cu²⁺ (maximum, 135 mg/g) which was taken as representative for metal ions. The present study provides an unprecedented class of biobased polymeric microspheres showing large potentials as adsorbents in wastewater treatment. Also importantly, the reactive aldehyde groups may enable the microspheres to be used as novel materials for immobilizing biomacromolecules, e.g. enzymes