RSC Applied Polymers最新文献

Degradable semiconducting polymers featuring acid-labile imine bonds are often investigated for use in transient electronics. However, the structure–property relationship of these polymers, particularly regarding degradation kinetics, remains underexplored. Herein, we designed and synthesized two imine-based semiconducting polymers which undergo an aromatic to quinoidal transformation upon acidification, leading to slower degradation rates compared to previously reported imine-based polymers. By utilizing a thieno[3,2-b]thiophene (TT)-inserted thienoisoindigo (TII)-dimer unit (TT-(TII-CHO)₂) and two diamines, p-phenylenediamine (PD) and 2,6-naphthalenediamine (2,6ND), we generated polymers p(TT-TII-PD) and p(TT-TII-2,6ND). The insertion of the TT unit between TII units results in high lying HOMO and low lying LUMO levels, facilitating a shift from an aromatic to quinoidal structure in the polymer backbone. Using ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy, infrared (IR) spectroscopy, and density functional theory (DFT) calculations, we investigated the influence of the quinoidal form on the degradation properties of these polymers. Notably, complete degradation of p(TT-TII-2,6ND) required over 30 days, indicating enhanced stability towards acid compared to previously reported TII-based polymers without the TT unit. Additionally, the protonated polymers demonstrated improved electrical properties compared to the pristine polymers, with field-effect transistor mobilities in the order of 10⁻² cm² V⁻¹ s⁻¹. These findings highlight the importance of quinoidal stability in modulating lifetimes and improving charge carrier transport in imine-based semiconducting polymers.

We show that dynamic covalent exchange at the interface of two thermosetting polymers results in strong bonding between the materials via creation of a new material at the interface. Thus, polymers of significantly different polarities can be bonded without the use of adhesives. We also show that such dynamic covalent exchange is not only limited to the interface but also penetrates into the bulk material (ca. 20 microns), thereby creating a strong bond. The creation of a new material at the interface was confirmed by Energy Dispersive X-ray (EDX) elemental mapping as well as a new glass transition temperature at the interface. Using this phenomenon, we show that hydrophobic, compliant polymers can also be used as adhesives for polar, stiff materials. We also show that such dynamic exchange also takes place in the presence of fillers like nano-silica. Lastly, using this technique, we demonstrate the adhesive-less fabrication of layered materials where each layer has vastly different polarities and mechanical properties, thereby tuning the failures modes of the resulting composite material.

The uncontrolled formation of a heterogeneous solid electrolyte interphase (SEI) and the growth of dendrites prevent the use of lithium metal anodes in Li-ion batteries. Possible strategies addressing these problems involve the formation of passivation surface coatings on the electrode. This study introduces a surface passivation strategy based on a covalently attached polymer coating to a hydroxide-modified lithium metal surface. The designed layer establishes a homogeneous and ion-permeable artificial SEI layer that is more stable than the untreated lithium metal anode, effectively preventing dead lithium aggregates and dendritic growth.

Advanced treatment of chronic wounds is critical to maintaining the physical and mental health of patients and improving their quality of life. Consequently, wound dressings with multifunctional properties are highly desired to achieve high wound closure effectiveness in chronic wound healing clinical applications. Therefore, an antioxidative dynamic hydrogel composed of aldehyde functionalised hyaluronic acid (HA-CHO) and disulfide functionalised chondroitin sulfate (CS-DTP) was designed. A disulfide moiety was utilised to functionalise chondroitin sulfate to introduce antioxidative functionality to the hydrogel scaffold. The dynamic covalent chemistry of the hydrazone network, which forms between the aldehyde and hydrazide functional groups, provides the hydrogel system with the desired properties of in situ rapid gelation and self-healing. The functional group content, rheology, self-healing, responsive degradation rate, ROS scavenging activity and cell biocompatibility of the hydrogels were characterised. Overall, this work demonstrates the facile preparation of a new dynamic hydrogel system, presenting a promising solution for wound care therapy as an antioxidative wound dressing.

Since the last century, plaster of Paris bandages have been the gold standard for orthopedic casting. Despite their extensive use, they have several drawbacks in day-to-day life, such as high weight and sensitivity to water. Moreover, they can cause skin burns, pressure sores, and other complications. Consequently, the urgency to propose alternative materials to solve these problems has emerged in the last decades, leading to the so-called soft casts, especially in pediatric orthopedics. In this context, a photocurable composite, based on the impregnation of a medical net with epoxy resins, is presented here. The impregnated medical net was rapidly transformed into a rigid device by means of visible light irradiation with an ad-hoc designed LED lamp (410–420 nm). Reaction activation was shifted to the visible range by exploiting isopropyl-9H-thioxanthen-9-one (ITX) as the photosensitizer, and the composites’ polymerization was evaluated via FT-IR analyses and thermal camera monitoring. The composites were also tested through tensile and three-point bending tests, revealing a stiffness comparable to that of soft casts already on the market. Compared to commercially available photocurable casts, this work introduces two key innovations: first, the employment of commercially available epoxy resins (monomer: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate), which enables avoiding the problems of oxygen inhibition; second, the use of a tubular medical net that is stretchable along the transversal direction, which is already used in the medical field for medication positioning. This latter advancement simplifies the application process compared to conventional techniques, making the obtained casts easy and fast to apply, light and breathable, thus maintaining promising properties for orthopedic rapid soft casts.

The development of amphiphilic block copolymer (ABP)-based nanoassemblies that degrade in response to dual stimuli at dual locations (e.g. hydrophobic cores and core/corona interfaces) offers a promising platform for controlled drug delivery. This work harnesses the features of an acid-labile benzoic imine (BzIm) bond and a glutathione (GSH)-cleavable disulfide linkage. We synthesized a poly(ethylene glycol) (PEG)-based dual location dual acid/GSH-degradable ABP with BzIm pendants in a hydrophobic polymethacrylate block and a disulfide at the block junction. The acid-catalyzed hydrolysis rate of BzIm depends on substituents attached to its para-position. Hydrolysis is faster with electron-donating substituents (methoxy), and slower with electron-withdrawing ones (bromo and nitro). Well-defined ABP synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization of a methoxy-substituted BzIm methacrylate in the presence of a disulfide-labeled PEG-based chain transfer agent, enables self-assembly to form colloidally-stable, monomodal, and spherical nanoassemblies. These nanoassemblies are capable of encapsulating cancer drug doxorubicin (Dox) and exhibit enhanced release of Dox through core degradation upon the cleavage of BzIm bonds in acidic pH and shell detachment upon the cleavage of disulfide bonds in the presence of GSH. Moreover, Dox-loaded nanoassemblies show excellent uptake by HeLa cell multi-tumor spheroids, demonstrating their potential as drug delivery nanocarriers. This study highlights the importance of substituent effects on the hydrolysis of BzIm and the dual acid/GSH-responsive strategy for developing a promising drug delivery system with precise control over drug release.

Aiming to develop antifogging materials with enhanced antifogging properties and scratch resistance, polysilsesquioxane films containing quaternary ammonium groups were prepared via a sol–gel reaction and quaternization. Owing to their high water uptake, scratch hardness, and transparency, the prepared quaternary ammonium-functionalized polysilsesquioxane films are promising for application in antifogging coatings.

Combining bioresources and photo-induced polymerization is a promising way to design sustainable and high-performing antibacterial materials. In this study, we propose a green synthesis of bio-based materials with dual antibacterial properties by photopolymerization. Two new methacrylate-based hydroxyanthraquinones derived from purpurin and alizarin (P-3Ac and Al-2Ac) have been designed to promote the polymerization of bio-based vegetable oil and terpene blend mixtures under visible-light irradiation up to 470 nm. All the photochemical mechanisms involved in the photopolymerization processes have been described by steady state photolysis, electron spin resonance spin-trapping (ESR ST) and real-time Fourier transform infrared (RT-FTIR) spectroscopy. Interestingly, the photo-initiating properties of P-3Ac and Al-2Ac are greatly enhanced in comparison with the native unmodified purpurin and alizarin. Polymerization of soybean oil acrylate and linalool through a thiol–ene process has led to the formation of photoactive bio-based materials able to generate biocide reactive oxygen species (ROS) upon light exposure which can also be used as contact-killing materials for tremendous inhibition of bacterial growth. The respective effects of each biocide agent (ROS and linalool) were compared and combined, highlighting stunning inhibition properties of the materials (higher than 99.99%) against both E. coli (Gram negative) and S. aureus (Gram positive), even after a second antibacterial recycling test. Prior to photo-printing experiments, rheological studies have been performed to design greener 3D-photoinduced materials. According to the high bio-renewable carbon contents of the photosensitive P-3Ac-based formulation and its great processability, 3D objects have been designed using Digital Light Processing (DLP) technology upon 405 nm light emitting diode exposure.

Creatures such as torpedo rays and electric eels showcase the exceptional ability to convert ionic gradients inside their bodies into powerful electrical discharges. In the future, artificial power units capable of reproducing this intriguing biological phenomenon may be able to power active devices, such as pacemakers and prosthetics, directly from ion gradients present in the human body. The present work evaluates the use of proton-selective Nafion membranes to generate electric power from the pH gradient present in the human stomach. First, we characterize two different commercial Nafion membranes by focusing on their ion exchange performance. In particular, we quantify the perm-selectivity of these membranes for various hydrated ions relative to that of the hydronium ion. Our results indicate that the transport of ions in wet Nafion proceeds through water-filled nanochannels, and that proton selectivity can be explained simply by the much larger mobility of protons in water with respect to other ions. Subsequently, we demonstrate a Nafion-based artificial electric organ capable of generating electric power from gastric juices. This power unit is built according to the reverse electrodialysis (RED) scheme, with each cell stack in series capable of generating 134 mV of potential difference and 188 mW m⁻² of power density.

The organizational states of functional monomer molecules have a significant impact on the properties of polymer materials. This Perspective summarizes amorphous conjugated polymer networks (CPNs) as a new family of polymerized structures. CPNs have been studied since the 1990s. The number of papers about CPNs increased in the 2010s after the earlier work was summarized in a review in 2005. However, the amorphous types had not attracted much attention in previous articles. Amorphous CPNs have potential structural advantages compared with conventional crystalline polymers and framework materials. Diverse combinations of monomers and linkers are used to synthesize amorphous CPNs. Conjugated monomers as functional units are not densely aggregated but are homogeneously dispersed in the network. The amorphous network contributes to structural flexibility for molecular motion related to dynamic properties. The low-crystalline nature affords control over the nanoscale morphology. This Perspective starts with a brief summary of polymerized structures. Our recent work is introduced to show the structures and properties of amorphous CPNs. Simultaneous and random copolymerization of multiple conjugated monomers provides amorphous CPNs. Enhanced electrochemical performance in energy-related applications was extracted from the resultant amorphous CPNs containing redox-active moieties, thanks to their structural characteristics. These results imply that a variety of advanced functional materials can be developed based on the concept of amorphous CPNs.