The morphology manipulation of the active layers is important for improving the performance of organic photovoltaics (OPVs). The choice of processing solvent has great impact on the crystallization and phase separation during film formation, since solvent properties, including solvent effect on molecular crystallization, boiling point, and interaction parameters, can directly change the evolution pathways associated with thermodynamics and kinetics. Therefore, revealing the underlying solvent-regulated morphology mechanism is potential to provide guiding strategies for device optimization. In this study, chloroform, chlorobenzene, and toluene are used to process PM6:Y6 blends by slot-die printing to fabricate OPV devices. The chloroform printed film forms a fibrillar network morphology with enhanced crystallization, facilitating exciton dissociation, charge transport and extraction, resulting in an optimal power conversion efficiency of 16.22%. However, the addition of the additive chloronaphthalene in chloroform solution leads to over-crystallization of Y6, and thus, increasing domain size that exceeds the exciton diffusion length, resulting in lower device efficiency. In addition, both the chlorobenzene and toluene suppress the crystallization of Y6, which drastically decreased short-circuit current and fill factor. These results demonstrate the important role of processing solvent in dictating film morphology, which critically connects with the resultant printed OPV performance.

In order to meet the demand for infrared stealth materials in the military field, conjugated polymers containing Schiff base moieties were designed and prepared. Various dialdehyde monomers were introduced and their effect on the comprehensive properties were systematically characterized. The resulted polymers could be cast in solution to prepare polymer coatings. The coatings exhibited high thermal stability up to 400 °C at 5% weight loss, and excellent mechanical performance with high Young's modulus and hardness. The infrared emissivity values varied from 0.587 to 0.627 at wavelength of 8−14 μm and ranged from 0.595 to 0.609 at wavelength of 2−22 μm. Specifically, it was found that the ATTPAL structure with carbazole moieties had a lower band gap and better electrical conductivity by photoelectric test and DFT theoretical analysis. Meanwhile, the infrared emissivity value of ATTPAL coating was the lowest compared with p-phenyl and pyridyl containing analogues, suggesting it was potential material for the future development of infrared stealth technology. The combined results showed that reducing the band gap and improving the electrical conductivity of the structure were both beneficial to the reduction of infrared emissivity. It would positively provide new ideas for the design of infrared stealth materials.

Covalent crosslinking points within thermosets generally result in excellent mechanical properties and solvent resistance yet lead to limited degradability and recyclability. Those thermosets become degradable or recyclable if crosslinking points are cleavable or reversible. Following this principle, we report a kind of polyurea-urethane thermoset with borate ester as its crosslinking point to enable a controllable de-crosslinking in response to acetate acid. Such a thermoset presents remarkable mechanical properties as well as outstanding solvent resistance capability, due to the high crosslinking density and intermolecular hydrogen bonding. Furthermore, the de-crosslinked product can be reporcessed to generate a brand new thermoplastic material.

Liquid metals (LM) refer to Ga-based alloys with low melting points such as Eutectic GaInSn alloys (EGaInSn), which have excellent fluidity, flexibility and low toxicity at room temperature. In this work, by incorporating EGaInSn into poly(acrylic acid) (PAA) hydrogels as dynamic crosslinkers and effective energy-dissipating units, tough and strong PAA-LM hydrogels are prepared through the interactions between the oxide layers on the surface of LM and carboxyl groups of PAA chains. Moreover, owing to the fluidity of LM, one LM droplet as a cross-linking point may change its shape or break into more and smaller droplets in the hydrogels upon stretching. Then hydrogels with self-adaptive networks can be fabricated by mechanical training through cyclic stretch at a certain elongation. Thus, the networks of the hydrogels are further homogenized, and the hydrogels are significantly toughened during the training due to the increased cross-linking density from the larger number of smaller LM droplets. After a 5-cycle training at the maximum strain of 500% and 24 h recovering, the tensile strength and initial modulus of the PAA-LM hydrogels can be increased from 355 kPa to 597 kPa and 71 kPa to 166 kPa, respectively, while the elongation at break only decreases from 1491% to 1034%.

The adsorption capacity of hydrogels derived from modified xylan hemicellulose has been tested in order to develop new bio-based adsorbent materials useful for removing metal ions pollutants, such as Cd(II), Cu(II) and Pb(II) from an aqueous solution. Xylan was extracted from bleached kraft pulp of eucalyptus and subsequently modified with different proportions of functional sulfonic acid groups (HA3−HA7) and sulfonate groups (HS30−HS70) to generate hydrogels. The results showed that all the synthesized hydrogels were capable of adsorbing metal ions, being the hydrogels with 30% and 50% xylan the ones that presented the highest adsorption capacity. Maximum capacity studies at different initial concentrations revealed that at an initial concentration of 300 mg·L⁻¹, the HA3 hydrogel presented an adsorption capacity of 193 mg Pb(II), 182 mg Cd(II), and 66 mg Cu(II) per g hydrogel. The HA5 hydrogel presented a capacity of 185 mg Pb(II), 113 mg Cd(II), and 48 mg Cu(II) per g hydrogel. The HS30 hydrogel exhibited an adsorption of 205 mg Pb(II), 174 mg Cd(II), and 71 mg Cu(II) per g hydrogel, and HS50 hydrogel exhibited an adsorption capacity of 273 mg Pb(II), 143 mg Cd(II), and 45 mg Cu(II) per g hydrogel. These results show that modified Xylan hemicellulose is a promising adsorbent for removal Cd(II), Cu(II), and Pb(II) ions from aqueous solutions.

Oxaliplatin is the common chemotherapy drug for the treatment of colorectal cancer (CRC), however, the harmful Fusobacterium nucleatum (Fn) that existed in the CRC tumor tissues leads to extreme drug resistance to oxaliplatin, which reduces the anticancer efficiency. Here we fabricated a new dendrimer-based nanocomplex with anti-tumor and antibacterial dual-functions through conjugating Pt(IV)-complex and lauric acid (LA) to the dendritic carrier PAMAM (G=3). The synthesized PAMAM-Pt-LA nanoparticle was further coated with hyaluronic acid (HA) on its surface through electrostatically interaction in order to enhance biocompatibility and tumor targeting. The biocompatibility, anti-tumor activity and antibacterial activity of PAMAM-Pt-LA@HA nanocomplex were evaluated in vitro. The results showed that the PAMAM-Pt-LA@HA nanocomplex ehxibited a good biocompatibility, high anti-colorectal cancer activity and high anti-Fn activity. This dual-functional nanocomplex provides a new method to develop anticancer nanomedicines that will be more therapeutically efficacious and less toxic than oxaliplatin for the treatment of CRC.

Miscible disordered block copolymers (BCPs) are rarely studied due to the limits in self-assembly into ordered microstructures. Herein, we proposed a facile method for the transformation of disordered miscible BCPs to comb-like BCPs with well-ordered microphase separation structures via blending with amphiphilic surfactants. In this work, poly(4-vinyl pyridine-b-hydroxybutylacrylate) (P4VP-b-P4HBA) was applied as a model of miscible disordered BCPs and the microphase separation was induced via blending with surfactants of dodecylbenzene sulfonic acid (DBSA) and 3-pentadecylphenol (PDP). The ordered microstructures including spherical and cylindrical morphologies were confirmed by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) investigation. These ordered microstructures thermal sensitive, in which ordered and disordered transformation (ODT) was observed in the blend of P4VP-b-P4HBA and PDP whereas it disappeared in the blend of P4VP-b-P4HBA and DBSA. The results show that the thermal stability of the ordered microstructures are strongly depends on the interactions between the miscible BCPs and surfactants, which investigated byin situ SAXS and Fourier transform infrared spectrometer (FTIR). The combination of miscible BCPs and surfactant creates a feasible strategy to fabricate ordered nanostructures, which could be employed to develop complicated nanomaterials.

Branched polyolefins with controllable topology structures were generated from the chain-walking (co)polymerizations of ethylene, 1-pentene (1P) and 2-pentene (2P) using Brookhart-type α-diimine Ni(II)-based catalysts possessing different para-substituted groups, {[(4-R-2-Et-6-Me-C₆H₂N＝C)₂Nap]NiBr₂, Nap: 1,8-naphthdiyl; R = CHMePh, Ni1; R = Ph, Ni2; R = H, Ni3}. The X-ray diffraction analysis demonstrated that the crystalline structure of Ni1′ is in centrosymmetric dimer structure mode with the bimetallic Ni center connected by two bromide bridges. The para-sec-phenethyl moiety in the catalyst Ni1 obviously improved its catalytic performance and thermal stability in the ethylene polymerization. The Ni1/Et₂AlCl system showed great catalytic activities (up to 7.73×10⁶ g·mol⁻¹·h⁻¹) and achieved polyethylene (PE) with alkyl chains, including Me, Et, n-Pr, n-Bu, sec-Bu branches and longer chains (Lg). Compared with the 1-pentene polymerization, this catalyst system successfully mediated the polymerization of 2P to give highly branched polymers with approximately 195 branches/1000C possessing Me, Et, and n-Pr branches and a long methylene sequence due to the monomer isomerization. The Et branches derived from 2,3-insertion is slightly less than the sum of Me and n-Pr branches derived from 3,2-insertion, indicating that the 3,2-insertion mode is a slightly favorable pathway in the polymerization of 2P.

Eucommia ulmoides gum (EUG) was a biobased hard rubber with the prospected broad applications in rubber products, whereas possessed poor elasticity and weak damping functionality at room temperature. After modification of EUG by triazolinedione-based Alder-ene reaction, the modified EUG containing varied amount of polar and branched pendants could become a new type of soft rubber and functional material with excellent damping properties, and especially exhibited the unique damping plateau with a wide effective damping temperature range of 132 °C covering from −35 °C to 97 °C, large loss factor of 0.8, high damping coefficient of 0.53, and more hysteresis loss of 0.35. Therefore, this sustainable elastomeric material with adjustable damping performance would absorb more vibrational mechanical energy in a wide temperature range, and have broadened applications in energy-absorption devices and shock-absorbing materials.

Epoxy resins are a kind of universal thermosetting plastics, which are widely used as structural materials in various applications. Thus, it is necessary to understand the network structure of epoxy resins. However, it is challenging to reveal the network heterogeneity of epoxy resins due to the permanent covalent crosslinking. Here, we provide a novel strategy to characterize the network heterogeneity of epoxy resins by using the dynamic covalent bonds to replace the conventional covalent bonds. The dynamic covalent bonds can reorganize under heat stimulus and the network keeps a constant crosslinking density during topological rearrangement, making it convenience to study the heterogeneity of epoxy resins. Kohlrausch-Williams-Watts (KWW) stretched exponential function is used to fit the stress relaxation data, and the parameters β and σ_perm/σ₀ extracted from KWW equation indicate the network becomes more homogenous with the stoichiometric ratio of epoxy groups and amines decreases from 1/1 to 1/1.5. This method proves that the side reaction between epoxy and hydroxyl is the main origin of the structural heterogeneity in epoxy resins compared to the secondary amines network.

Fluorinated diols (FDO) with dangling chain were introduced into polyether urethanes (PEUs) as chain extender in order to achieve internal plasticization. Based on temperature dependent Fourier transform infrared (FTIR) spectroscopy results, the fluorinated polyether urethanes (FPEUs) exhibited weaker hydrogen bonding between C＝O and N―H groups with addition of FDO. The crystallinity of hard domain was destroyed determined by thermal analysis. Combined with the results of dynamic mechanical analysis (DMA) and dissipative particle dynamics (DPD) simulation, it was proved that more loosely aggregated hard domains with weakened interaction separated from soft segment were formed. Rheological analysis indicated that FDO reduced the complex viscosity and viscous flow activation energy which endowed the polymer with more flexibility. Despite the loss of hydrogen bonds, there was no significant decline in mechanical property resulting from the decrease of hard segment dissolved in soft segment phase. The presence of fluorinated carbon side chain could function as internal plasticizer and contribute to the processability of polyurethane.

Fabrication of polyethylene (PE) pipe with significantly enhanced hoop strength and burst pressure is essential necessary for high transportation requirements. In this work, biaxially oriented PE/ultrahigh molecular weight polyethylene (PE/UHMWPE) blend pipes were fabricated on self-made pipe solid-phase die drawing apparatus. Due to formation of chain entanglement network and enhanced viscoelasticity, incorporation of UHMWPE chains improved stretchability and biaxial orientation degree of blend pipe. During die drawing, formation of more miscible blend system make long UHMWPE chains be sufficiently stretched under load, and such extended-chain conformation of UHMWPE acted as shish structure and induced short PE chains to array orderly and form kebab crystals. With increasing axial draw ratio, the lamellae remarkably deviated from hoop to axial direction, while the blend pipe exhibited higher crystallinity and orientation degree than that of PE pipe, presenting a more uniform and dense biaxial orientation structure with shish-kebab crystals. As a result, the blend pipe showed roughly 99% increase in tensile strength along hoop direction and 25% increase in burst pressure, respectively. Such biaxial self-reinforced PE/UHMWPE blend pipes exhibit promising application prospect as high-pressure transportation pipelines in civil engineering.

A series of thermoplastic polyimide resins with a low coefficient of thermal expansion (CTE) were prepared by blending a rigid resin system 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA)/p-phenylenediamine (PDA) with a flexible resin system 4,4'-[isopropylidenebis(p-phenyleneoxy)]diphthalic anhydride (BPADA)/PDA. The effects of the blending ratio on the macromolecular coil size, free volume, and CTE of the mixed system were studied. The mixing is carried out in the prepolymer poly(amide acid) (PAA) stage, which makes the two systems more compatible and is conducive to the formation of a semi-interpenetrating network structure between the rigid molecular chains and flexible molecular chains. The flexible structure of the BPADA/PDA system is used to ensure the melt processing performance. The rigid characteristics of the BPDA/PDA system can inhibit the movement of molecular chains and reduce the free volume fraction, thereby reducing the CTE value. When the rigid system content reaches 30%, the CTE can be reduced to 38 ppm/K. This method provides a new approach for studying low CTE thermoplastic polyimide resins.

All-PLA fibers with excellent comprehensive performance and recycling convenience are realized efficiently. High molecular weight poly(D-lactide) (HPDLA) is incorporated into poly(L-lactide) (PLLA) matrix to construct in situ nanofibrils structure by taking advantages of the microphase separation between HPDLA and PLLA. The tensile strength of HPDLA/PLLA composite fibers (HDL-8) is enhanced from 2.1 cN/dtex of neat PLLA-8 fibers up to 2.9 cN/dtex. Its boiling water shrinkage (BWS) and shrinkage in hot air (HAS) significantly decrease to 7.8% and 2.8%, respectively. The abundance of in situ nanofibrils creates a grille-like structure that is crucial for both heat and hydrolysis resistance. More strikingly, a hybrid shish-kebab structure induced by the in situ nanofibrils serves as a mechanical reinforcement. This work paves a new way for heat resistance and self-reinforcement modification of PLA materials.

The mechanism of the phase separation of polymer blends in the presence of a static electric field was investigated using the molecular dynamics with a modified coarse-grained polarizable model. Two electric field effects, i.e., the promotion and hindrance of the phase separation, were found in the system of the upper critical solution temperature (UCST) by varying the dielectric properties of polymer components. Our simulation directly demonstrated that the electric field effects originate from the energy changes of intramolecular unit polarization, intermolecular van der Waals (VDW) and Coulomb interactions induced by the external electric field. The relationship of the energy change and the dielectric constant for the system under electric field is obtained. The interface orientation under electric field was found to happen even before the transition point of phase separation. By assuming that the relative order parameter of the phase separation undergoes the same fluctuations for a system with and without an electric field, the transition temperature under an electric field can be predicted, and quantitative consistency with simulations is obtained.

Nano-injection molding enables the formation of nano-scale anchors to connect heterogeneous material surfaces to achieve the required mechanical properties. In this work, polyphenylene sulfide (PPS), aluminum (Al), copper (Cu), and iron (Fe) were selected as candidate polymer and metal materials. Three kinds of polymer-metal interfacial models with pyramidal nano-slots were modeled. The molecular dynamics simulations were launched to investigate the adhesion properties and molecular kinematic mechanisms of heterogeneous interfaces in nano-injection molding. Results showed that the wall-slipping behavior of PPS at the interface slot was obvious, it was easy to form multiple-anchor-points in the central area of substrates, and these anchor points were easily slipping along the wall, different from the de Gennes model. The atomic lattice and atomic band gap of metal affected the adhesion strength. The BCC lattice of Fe was more suitable for nano-injection molding process than the FCC lattice of Al and Cu. The filling rate, interfacial energy, the tensile and shear failures data revealed that the interfacial adhesion performances decreased according to the following order, Fe-PPS, Cu-PPS and Al-PPS components, respectively, and the interface failure mode was closely related to the stress loading mode.