Vegetable oil is one of the most promising renewable feedstocks as an alternative to fossil resources, but there are few studies aiming to transform it into hydrophilic materials. We proposed a facile method to prepare water-soluble derivatives from soybean oil, which could become water resistant again after simple heat treatment. The model vegetable oil, soybean oil (SO), was first reacted with maleic anhydride (MA) by the Alder ene reaction to obtain maleinized soybean oil (SOMA), and SOMA was further reacted with gaseous ammonia to obtain the maleamic acid form (SOMA-Amic acid), which was very soluble in water (solubility>100 mg/mL). The obtained water-soluble product was converted to the water-resistant maleimide form (SOMA-Imide) by a simple heat treatment. The potential application of these vegetable oil derived materials was demonstrated in paper sizing as an example. SOMA-Amic acid was demonstrated to be a novel green material, which can be used in an aqueous process and then heat-treated to become water-resistant in the final product.

We present a ring-opening polymerization of bridged cyclic lactone utilizing alcohol as the initiator and organic base as the catalyst. Bridged γ-butyrolactone monomers (PhSGBL and PhSeGBL) were synthesized efficiently from commercially available 3-cyclohexene-1-carboxylic acid. Due to the ring strain of the bridged structure, ring-opening polymerization of this type of γ-butyrolactone derivative was successfully carried out under mild conditions, e.g., using ethylene glycol as the initiator and a commercial catalyst [1,5,7-triazabicyclo [4.4.0 dec-5-ene (TBD)] as the catalyst at 30 °C. The obtained polymer could be degraded to its monomer for recycling in the presence of ZnCl₂ as a catalyst. PhSGBL and PhSeGBL could also be copolymerized with ε-caprolactone to tune the glass transition temperature. Additionally, the hydrophilicity of the obtained sulfur-containing polymers could be adjusted by selectively oxidizing the thioether side group to sulfone/sulfoxide, which offered a way to tune the hydrophilicity of polyester. On the other hand, the obtained selenium-containing compound could be degraded in the presence of m-CPBA (3-chloroperbenzoic acid), which offered potential application in sustained drug release.

Hydrogen-bonded polymer complex fiber of poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) shows rubber elasticity in ambient environment, but the fiber has relatively low strength and weak stability. We apply the catechol chemistry and metal coordination to stabilize and strengthen the PEO/PAA fiber. PAA is grafted with dopamine (Dopa), and then combines with PEO to prepare fiber. PAA-Dopa in the fiber is cross-linked through oxidation induced dismutation and the metal ions are introduced through coordination. The cross-linking and coordination greatly improve the stability of the fiber against the erosion of alkaline water. Among four different metal coordination fibers, PEO/PAA-Dopa/Cu fiber keeps the excellent extensibility (~1000%) and presents much higher initial modulus (~7 MPa), ultimate strength (~20 MPa), and toughness (~60 MJ/m³) than its precursor PEO/PAA fiber. In addition, PEO/PAA-Dopa/Cu fiber shows quick recovery and large energy dissipation ratio compared with the PEO/PAA fiber. The distinct mechanical properties enhancement of the hydrogen-bonded complex fiber is attributed to the synergy of hydrogen bonds, coordination and covalent bond cross-linking.

The alternating copolymerization of hydroxyalkyl vinyl ethers and dialkyl maleates is investigated by conventional radical polymerization and reversible addition-fragmentation chain transfer polymerization (RAFT). The influence of comonomer structure, comonomer feeding ratios, and monomer concentrations on the copolymerization and the copolymer structure have been investigated systematically. With 2-hydroxyethyl vinyl ether (HEVE) and dimethyl maleates (DMM) as comonomers, a well-defined alternating copolymer is prepared with M_n=3400 and M_w/M_n=1.93 up to 71.6% monomer. The alternating sequential chain structure of the copolymers has been proved by both NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The experimental reactivity ratios and theoretical calculated highest occupied molecular orbital and the lowest unoccupied molecular orbital of vinyl ethers and alkyl maleates support that these monomer pairs have tendency to form alternating copolymers. With 2-cyanopropan-2-yl N-methyl-N-(pyridin-4-yl)carbamodithioate as the RAFT agent, the molecular weight of HEVE and DMM copolymer increases with the monomer conversion, demonstrating a controlled radical polymerization feature with well-controlled molecular weight and relatively narrower molecular weight distribution. With alternating copolymer of HEVE and DMM as macro-CTA (M_n=5200 and M_w/M_n=1.46), both the chain extension with HEVE and DMM (M_n=10400 and M_w/M_n=1.72) and block copolymerization with vinyl acetate have been successfully achieved (M_n=8500 and M_w/M_n=1.52).

Polylactide (PLA) has often been blended with biodegradable poly(butylene adipate-co-terephthalate) (PBAT) to improve its toughness. However, the strength and heat resistance of PLA are always sacrificed. Herein, exchangeable hydroxyl-ester crosslinks are constructed in PLA/PBAT blends by successively introducing a tertiary amine-containing polyol, bis-(2-hydroxyethyl)amino-tris (hydroxymethyl)methane (BTM) and 4,4’-diphenylmethane diisocyanate (MDI) via reactive blending. BTM can react with both PLA and PBAT by transesterification, generating PLA or PBAT chains with terminal or pendant hydroxyl groups, which can then react with MDI to form networks. With internal catalysis of tertiary amine moiety in BTM, transesterification between the residual hydroxyl groups and ester bonds can occur at high temperatures, endowing the PLA/PBAT network with vitrimeric properties. Owning to the transesterification and chain extension reactions with MDI between PLA and PBAT, the interfacial adhesion is greatly improved. As a result of the excellent interfacial adhesion and the network structure, the prepared PLA/PBAT blends show greatly enhanced heat resistance and toughness (more than 40 times that of PLA) while maintaining high stiffness comparable to PLA. Furthermore, the prepared PLA/PBAT blends exhibit promising reconfigurable shape memory behavior. The present work provides a new and facile way to achieve high-performance and functional biodegradable polymeric materials.

PEGylation is the gold standard for constructing protein resistance surfaces. Herein, grafting mPEG-SH and SH-PEG-SH with varied molecular weights (Mw=5K, 10K, and 20K) on a gold chip, and the subsequent lysozyme adsorptions of the PEG layers are evaluated using quartz-crystal microbalance based on dissipation (QCM-D). The lysozyme resistance depends on the features of grafting density and chain conformation, i.e., linear and looped conformation. However, long-chain PEG (Mw≥10K) is insufficient to form a dense layer to resist protein due to large steric hindrances. Short-chain PEG (Mw=1K) with linear and looped structures is used to refill onto the long-chain PEG layer to increase the grafting density of PEGs and improve protein resistance. The refilling process and the subsequent protein adsorption depend on conformation rather than the density of the long-chain PEG substrate. Notably, the long-chain PEG looped substrates significantly improve protein resistance, attributing to the high viscoelasticity of the looped substrate and an increase in grafting density after refilling. Thus, refilling short-chain PEG improves protein resistance and the substrate conformation-dependence gives insight into the impact of topology, providing new ideas for how to increase chain density and select suitable topology to resist protein adsorption and demonstrating a potential application in biomedical fields.

Reasonable construction of high activity and low cost non-noble metal oxygen reduction reaction (ORR) catalyst is of great importance for the wide application of zinc-air batteries (ZABs). Using bimetallic MOF as a precursor combined with electrospinning, high-temperature carbonization and electrodeposition, we successfully developed a porous carbon nanofiber (Co@Fe-CNFs-1000) with bimetallic active center as an efficient catalyst for ORR. The successful construction of this special core-shell structure directly explores the synergy between different active centers. The results showed that the synthesized Co@Fe-CNFs-1000 catalyst exhibited ORR performance comparable to that of Pt/C in 0.1 mol/L KOH electrolyte, high half-wave potential (E_1/2=0.81 V) and limiting current density (J_L=5.4 mA·cm⁻²). In addition, homemade liquid ZABs with Co@Fe-CNFs-1000 as the air cathode showed excellent power density (155.8 mW·cm⁻²), specific capacity (780.6 mAh·g_Zn⁻¹) and long-term stability (over 100 h at 2 mA·cm⁻²), surpassing even Pt/C-based batteries. In addition, the flexible solid-state ZABs assembled based on Co@Fe-CNFs-1000 demonstrates excellent flexibility and durability. This work provides a new idea for constructing ORR catalysts with high activity centers.

The microstructural evolution of a thermoplastic polyurethane (TPU) with low hard segment content has been monitored utilizing in situ real-time synchrotron small angle X-ray scattering (SAXS) and time-domain nuclear magnetic resonance (NMR) measurements. The TPU is composed of 23 wt% of [4,4-methylenediphenyl diisocyanate (MDI)]-[1,4-butanediol (BD)] chain segments, which form hard domains, as [polytetrahydrofuran (PTHF)] forming soft domains. The number and distribution of monomer units in hard blocks is determined by the successive self-nucleation and annealing thermal fractionation technique.In situ SAXS method reveals heating-induced increase in the spacing of hard and soft domains, while time-domain ¹H-NMR characterizes the changes in the phase composition and chain dynamics in these domains. A glassy fraction of short MDI-BD chain segments in hard domains passes through T_g above ambient temperature. At higher temperatures, MDI-BD nanocrystals start to melt. Sequence length distribution of MDI-BD chain segments causes a distribution in crystal sizes and wide melting temperature range. The melting is accompanied by the mixing of MDI-BD with PTHF segments in soft domains, and by increase in segmental mobility in these domains. Above 180 °C, the TPU melt is homogeneous on the scale above nanometers according to SAXS data.

In this work, the self-nucleation effect on crystallization was studied for polypropylene with various nucleating agents. The talc was employed to accelerate crystallization of monoclinic α-crystallites, while N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide TMB-5 was used to accelerate the crystallization kinetics and also induce formation of trigonal β-crystallites. To induce self-nucleation effect, the occurrence criterion was assessed by the transition temperatures from various domains and the available temperature width. More importantly, the resulting influences of self-nucleation effect were quantified by the change of crystallization kinetics and the potential polymorphism variation. It was found that the α-nucleating agents of talc broadened the temperature window for inducing Domain II by elevating the transition temperature from Domain I to Domain II. Although β-nucleating agent (β-NA) of N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide TMB-5 elevated cooling crystallization temperature obviously, the temperature window for Domain II was narrowed. It should be emphasized that in presence of β-NA TMB-5, the self-nucleation effect enhances the crystallization of α-crystallite, which show the competition with β-NA TMB-5. At last, the ternary PP/talc/TMB-5 blend was prepared with the same amounts of α-NA talc and β-NA TMB-5 and it exhibits a similar self-nucleation effect of crystallization, indicating the dominant role of β-NA TMB-5.

Polyimide-based composite films with high thermal conductivity, good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics fields. As one of the key technical challenges to be solved, interfacial compatibility between filler and matrix plays an important role for composite film. Herein, boron nitride was modified by grafting polyimide brushes via a two-step method, and a series of thermally conductive polyimide/ boron nitride composite films were prepared. Both characterization and performance results proved that the interfacial interaction and compatibility was greatly enhanced, resulting in a significant reduction in defects and interfacial thermal resistance. The interphase width of transition zone between two phases was also efficiently enlarged due to polyimide brushes grafted on filler surface. As a result, composite films based on polyimide-grafted boron nitride exhibited significantly improved properties compared with those based on pristine filler. Tensile strength can reach up to 80 MPa even if the filler content is as high as 50 wt%. The out-of-plane and in-plane thermal conductivity of composite film increased to 0.841 and 0.850 W·m⁻¹·K⁻¹, respectively. In addition, thermal and dielectric properties of composite films were also enhanced to some extent. The above results indicate that surface modification by chemically grafting polymer brushes is an effective method to improve two-phase interfacial compatibility so as to prepare composite film with enhanced properties.

Separator is a pivotal component of lithium-ion batteries (LIBs) and determines the electrochemical performance and safety. However, with the increase in energy density and application scenarios, commercial polyolefin separators are increasingly unable to undertake heavy responsibility of battery safety protection. Herein, a new kind of nanofiber separator based on poly(ether ether ketone) (PEEK) with excellent thermal stability, self-extinguishing, and superior electrochemical properties is reported. Effective inheritance of intrinsic properties from raw PEEK materials and optimized hot-pressing operation endows the separator with high robustness and wettability, showing tensile strength of 15.8 MPa and a contact angle of 17.2°. The high thermal stability of PEEK can ensure the separator to preserve the structural integrity and microstructure at temperatures beyond 300 °C, and the excellent self-extinguishing peculiarity of PEEK capacitates the high safety of LIB. Notably, benefitting from high porosity and polar surface, the PEEK separator shows high electrolyte uptake of 245.5% and exhibits a wider electrochemical window and faster lithium-ion transport number than commercial polyolefin separators. Furthermore, cells assembled with PEEK separator display better performance than the ones with PE separator, and the PEEK LIB has been successfully used to light up a lamp at a high temperature of 150 °C.

Incorporation of carbon black (CB) in natural rubber (NR) enhances the Mullins effect and Payne effect of their vulcanizates, but the strain softening mechanisms and the microstructure evolution in the vulcanizates have not been clearly concluded so far. We investigate the Mullins effect and Payne effect of CB filled NR vulcanizates by using cyclic tensile tests at different temperatures and dynamic rheological measurements combined with simultaneous electric conduction. During cyclic stretching, the normalized recovery hysteresis energy and accumulative softening energy for NR/CB vulcanizates with different loadings can be both superimposed on a master curve, indicating that the Mullins effect is mainly dominated by the rubber matrix. The irreversible simultaneous resistance evolution also reveals that the structural evolution of nanoparticles (NPs) network is not directly related to the Mullins effect. Moreover, the extension of linear viscoelastic region and the hysteresis of Payne effect for filled vulcanizates subjected to cyclic stretching indicate the destruction of CB aggregated structure and the interfacial layers between CB and rubber chains during cyclic stretching. This investigation would be illuminating for the microstructure evolution and strain softening of rubber nanocomposites under harsh service conditions.

How to achieve both toughness and enhanced electromagnetic interference shielding effectiveness (EMI SE) of carbon fibers (CFs) reinforced rigid polyurethane (RPU) composites is a significative challenge at present. In this work, a ring-shaped zinc coating was deposited on the short CFs by electrodeposition technique. It is expected to improve the interfacial properties between the fibers and the resin matrix as well as enhance the EMI shielding properties of the composites by changing the surface morphology and roughness of the fibers. Results showed that the surface free energy of the ring-shaped zinc modified carbon fibers (RS-CFs) increased from 49.0 mJ/m² to 53.2 mJ/m², indicating that the surface roughness and wettability of the CFs were effectively improved. In comparison with the pristine short carbon fibers/rigid polyurethane (CFs/RPU) composites, tensile strength and tensile toughness of RS-CFs modified composites were increased by 27.1% and 121.4%, respectively. In addition, the bending and impact strengths of RS-CFs reinforced RPU composites were also improved. Notably, the electrical conductivity of RS-CFs/RPU composites reached 1.2×10⁻⁵ S/m, which was much higher than that of CFs/RPU composites at 1.4×10⁻¹⁰ S/m. Moreover, the EMI SE of the modified composites reached 22 dB, which was 152.9% higher than that of CFs/RPU composites. The enhanced electrical conductivity and EMI shielding properties of the composites could be attributed to the synergistic effect of the porous structure in the RPU matrix and the CFs modified by the metal coating.

The present work involves the investigation of the synergistic effects of gamma irradiation, tensile stress and absorbed moisture on the radiolysis behaviors of silicone foams by experiments and theoretical simulations. For both the pristine and dehydrated samples, the permanent tensile set increases with the initial tensile strain. Further analysis uncovers that the dehydrated samples exhibit greater permanent tensile sets, lower further elongation and higher Young’s modulus than the counterparts of the pristine samples with the same initial tensile strain and gamma dose, verifying the vital synergistic effects on crosslinking network and aggregation structures caused by moisture and gamma radiation. The synergistic effects unveiled by reactive molecular dynamics at the atomic scale are due to the moisture-induced neutralization and stabilization of the macromolecular radicals. The steric hindrance of moisture located at the interface of silica and polymer chains also conduces to the observed synergistic effects due to the inhibited crosslinking reactions.