RSC Applied Polymers最新文献

Low voltage operation in organic field effect transistors (OFETs) requires dielectric materials with extremely large capacitance. We explored a novel zwitterion-based dielectric material prepared using 4-(3-Butyl-1-imidazolio)-1-butanesulfonate (ZI) in a poly(vinyl alcohol) (PVA) polymer matrix. P-type OFET devices were fabricated with poly(3-hexylthiophene-2,5-diyl) (P3HT), their performance was found to be strongly humidity dependent with humidified devices producing roughly the same current at a voltage nearly 30 times lower than devices tested under an inert atmosphere. N-type OFETs based on poly{[N,N′-bis(2-octyldodecyl)napthlene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (P(NDI2OD-2T)) also showed improved current levels in humidified devices, but possessed a low on/off ratio. Impedance measurements of the dielectric film showed a marked increase in the magnitude and frequency response of the capacitance with increasing humidity. The process can be modelled in terms of a single rate-limiting process using the Havriliak–Negami equation. Infrared spectroscopy was used to further examine the intermolecular interactions responsible for the humidity-dependent capacitance. Changes were observed in the spectrum of PVA with ZI inclusion and with respect to humidity. We hypothesize that the ZI molecules rotate in response to an applied field and that rotation is inhibited by strong intermolecular interactions between ZI molecules and the polymer matrix under dry conditions. This hypothesis also can be used to rationalize the low on/off ratio of the P(NDI2OD-2T) transistors. In sum, we demonstrate a material with capacitance values approaching those of an electrostatic double layer and demonstrated that local intermolecular interactions are central to understanding material behavior.

We fabricated a movable cross-linked elastomer derived from a pseudo-rotaxane by utilizing a dimer structure, in which the ring molecules made a threaded structure onto a polymer backbone, by simple bulk polymerization. The pseudo-rotaxane cross-linked elastomer exhibited facile healing and good stretching corresponding to the stress relaxation, which can contribute to the increment of fracture energy. We separated the topologically cross-linked dimer compounds from the threaded polymer backbone compound, constituting a recyclable cross-linker for a circular economy as a sustainable material.

Non-aqueous emulsions are employed for a host of important applications; however, their long-term stability often limits their use. 2D particles have been reported to provide greater emulsion stability compared to surfactants and isotropic particles as a result of their greater interfacial area interaction. Here, control over the particle size resulted in control over the droplet diameter and increased stability. Non-aqueous emulsions are widely employed; therefore, characterising the effect of the dimensions of 2D particles on their stability is key to making oil-in-oil (o/o) emulsions with enhanced properties. This study investigates the self-assembly of uniform 2D particles of a controlled size, and their application as Pickering particles in o/o emulsions. The correlation between 2D particle dimensions and emulsion characteristics was investigated, a comparison that has not been reported for o/o emulsions prior to this study.

Over the past five years, there has been a notable increase in the application of three-dimensional (3D) printing techniques mediated by reversible addition–fragmentation chain-transfer (RAFT) polymerization. This increasing interest is due in part to the associated benefits that RAFT 3D printing systems provide, including tighter control over macromolecular network structures and the ability to easily prepare multifunctional materials. In parallel, deep eutectic solvents that feature polymerizable components, called polymerizable eutectics, have also been gaining attention for their outstanding properties and ease of manufacture of functional polymer materials. In this work, we develop polymerizable eutectic resins that contain RAFT agents and are suitable for application to visible-light induced vat 3D printing. The combination of the polymerizable eutectic components and a Z-connected bis-RAFT agent in the resin provides the resulting materials with excellent properties derived from both the eutectic components and the degenerative chain transfer mechanism of RAFT polymerization. While the base (non-RAFT) polymerizable eutectic materials display high modulus and adhesive strength on their own, the inclusion of RAFT agents provides materials with higher adhesive strength while retaining their high strength to higher temperatures. Moreover, the selection of N-isopropylacrylamide as one of the eutectic components provides these materials with reversible thermoresponsive behavior in water. The high shape fidelity and ease of preparation of these materials could be of potential use in the design of 3D printable biomaterials and actuators.

Thiol-maleimide conjugation is a well-established coupling method in biochemistry but with little reported use within silicone materials. A facile synthetic route of functionalised poly(dimethyl siloxane) (PDMS) to a prepolymer species capable of non-metal-catalysed cross-linking via thiol-Michael addition is presented. Two systems are compared: maleimide (MI) terminated PDMS and its precursor, maleamic acid amide (MA) terminated PDMS. Despite the traditional view of maleamic acid amide functionalities as being of inferior value to their maleimide counterparts, we argue for their potential. The increased relative concentration of polar groups in a robust MA network matrix can be exploited for better electrical properties for self-healable dielectric elastomer actuators, as demonstrated by the MA networks with their quadruple hydrogen bonding centres, self-healing capabilities, increased polarity, good electrical breakdown strength, and increased dielectric permittivity over both commercial and MI PDMS networks.

The continuous accumulation of electronic waste is reaching alarming levels, necessitating sustainable solutions to mitigate environmental concerns. Fabrication of commercial electronic substrates also requires wasteful high heat. To this end, we develop a series of reprocessible electronic substrates based on photopolymerizable polyimides containing degradable ester linkages. Five imide-containing diallyl monomers are synthesized from readily available feedstocks to produce high-quality substrates via rapid photopolymerization. Such materials possess exceptional thermal (thermal conductivity, K = 0.37–0.54 W m⁻¹ K⁻¹; degradation temperature, T_d > 300 °C), dielectric (dielectric constant, D_k = 2.81–3.05; dielectric loss, D_f < 0.024), and mechanical properties (Young's modulus, ∼50 MPa; ultimate elongation, dL/L₀ > 5%) needed for flex electronic applications. We demonstrate mild depolymerization via transesterification reactions to recover and reuse the functional components.

Hydrogenation is one of the important functional group conversion reactions in the chemical industry. In this study, a cellulosic protic ionic liquid hydrogel was firstly synthesized by adding mixed cyclic anhydrides into a cotton pulp cellulose solution in TMG (1,1,3,3-tetramethyl guanidine)/CO₂/DMSO to form the cellulosic protic ionic liquid hydrogel (CPILH) through an esterification reaction. The CPILH confined Pd nanoparticle (Pd@CPILH) catalyst was prepared by anchoring Pd²⁺ ions through the large functional groups on the CPILH (e.g., –COOH and TMG-based protic ionic liquids (TMGPILs)) and then an in situ reduction of Pd²⁺ to Pd NPs. TEM analysis revealed that the Pd NPs had a small size of 4.4 nm and were well dispersed within the matrix. As a result, catalytic hydrogenation of α-AL successfully formed GVL, with a conversion rate of 97.7% and 100% selectivity achieved within 3 hours at 50 °C in ethanol. Kinetics experiments were performed by adjusting the reaction temperature within the range of 30 to 65 °C, and the simulated data fitted well with the first-order kinetic law. The reaction rate constant (k) was determined to be 0.2226 min⁻¹ at 50 °C, and the reaction activation energy (E_a) was calculated to be 30.45 kJ mol⁻¹. The Pd@CPILH catalyst demonstrated remarkable recyclability, maintaining high conversion and selectivity even after 10 uses. Additionally, the catalyst exhibited excellent catalytic efficiency, achieving nearly 100% conversion and selectivity for common alkenes under moderate conditions. This work presents a straightforward and sustainable strategy for the synthesis of catalyst support materials, showcasing significant potential in the production of chemicals derived from biomass.

Polymer networks possessing reversible covalent crosslinks have emerged as an interesting type of material that combine the excellent performance of thermoset materials with the processability of thermoplastic materials. Several studies have focused on different reversible bonds. However, little or no attention has been paid to degradation events occurring during reprocessing. In this study, we utilize ¹H NMR spectra coupled with chemometric methods to define the best processing conditions for aromatic disulfide-based vitrimers. By using a principal component analysis (PCA) tool, we show it is possible to gauge which variable has a greater impact on the degradation of aromatic disulfides. Analyzing 80 different spectra simultaneously, the PCA reveals that from the analyzed variables, the processing time is the most influential variable, followed by temperature. Using Multivariate Curve Resolution (MCR) models we show that it is possible to estimate the extent of degradation as a function of the different experimental conditions. The data obtained with model compounds using chemometrics has been validated by analyzing the impact of reprocessing conditions in vitrimer networks. Our study suggests that NMR analysis combined with chemometric tools can provide highly valuable information to define processing conditions for covalent adaptable networks with minimal degradation.

Over the past decade, research interest has grown rapidly in covalent adaptable networks, called vitrimers, which can balance the processability and recyclability of thermoplastics with the performance properties of thermosets, including elastomers. While most vitrimer research focuses on generating new materials, several studies have demonstrated that permanently crosslinked networks can be transformed into covalent adaptable networks through a mechanochemical process. This finding points to an effective and efficient technical approach for upcycling waste thermoset plastics. Recent studies have demonstrated that crosslinked ethylene vinyl acetate (EVA) thermosets can be converted to vitrimers using a mechanochemical process employing a zinc-catalyzed transesterification reaction. The concept has been applied successfully to vitrimerize crosslinked EVA elastomers and foams, including shoe midsole foam, which is otherwise difficult to recycle. To investigate whether catalyst selection could be used to control the crosslink exchange kinetics and network properties of the vitrimers produced, we compare the effects of different zinc catalysts on the vitrimerization of crosslinked EVA elastomers. We use a computational chemistry approach to select zinc catalysts with different small molecule activation energies and then apply these catalysts to vitrimerize crosslinked EVA. We find that the flow activation energies measured by experiments for the dynamic network exchanges are markedly different from the activation energies predicted by simulation for small molecule exchange. Our results suggest that the dynamic exchange rates of vitrimerized crosslinked EVA elastomers depend not only on the activation barrier for small molecule exchange but also on catalyst physical properties such as the molecular size and stability at the processing temperature.

Research over the past four decades on polyaniline has matured, and consequently it has become one of the most popular conducting polymers. Also, several methods have been proposed by researchers for the synthesis and conversion of polyaniline (PANI) to various forms as well as its doping with chalcogens especially selenium (Se) and tellurium (Te). These composites have been explored using various chemical methods and their different properties have been extensively studied in terms of electrical, thermal, morphological and optical behaviour. This review summarizes the results from research experiments, including their synthesis and characterization, and the study of their various properties such as DC conductivity measurements, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, field emission studies, EMI shielding behaviour, and electrochemical, supercapacitive, optoelectronic and thermoelectric properties. The incorporation of chalcogens in PANI leads to a significant improvement in its electrical conductivity and field emission properties, making the resulting nanocomposites promising materials for various electronic applications. The global energy crisis underscores the need for innovative materials for the production of energy. In this case, solution-based polymer thermoelectric (TE) technologies offer an eco-friendly and cost-effective approach to convert heat into electricity. The successful electrodeposition of tellurium films onto phenolic foam with PANI coatings and the synthesis of novel PANI/Te nanocomposites with enhanced nonlinear optical properties open up new avenues. These nanocomposites were prepared using different methods including simultaneous electrochemical reactions, in situ polymerization, and interfacial polymerization.