Copper(0)-mediated reversible-deactivation radical polymerization (Cu(0)-mediated RDRP) of the water-soluble monomer N-isopropylacrylamide (NIPAM) has been challenging with the problems of high dispersity, poor control over the molecular weights (MWs) or complex or multi reaction steps, etc. In this work, we report the well-controlled polymerization of NIPAM in water via a facile one-pot and one-step Cu(0)-mediated RDRP. The results of this approach show that the key for kicking off the Cu(0)-mediated NIPAM RDRPs is to ensure sufficient Cu^I at the very beginning, and the key to achieve a well-controlled chain growth is to provide adequate deactivation strength during the polymerization process. For NIPAM, which has a high propagation rate constant, the deactivation control can be effectively enhanced by extra adding deactivator (i.e., Cu^II) to the system. Moreover, a low reaction temperature (4 °C) is necessary in the controlled synthesis of higher MW poly(N-isopropylacrylamide) (PNIPAM) to avoid the compromise in control caused by the phase transition from its lower critical solution temperature (LCST). Through this new kinetically controlled strategy, PNIPAMs with well-defined structure, narrow molecular weight distributions (MWDs) and varied MWs were successfully achieved.

This work reported an AIE fluorescent probe for tumor imaging based on the pH induced self-assembly strategy. The fluorescent probe was composed of an acid-responsive soluble copolymer PEG-b-PAMA-DMMA with a maleic acid amide group and an anionic soluble aggregation-induced emission fluorogen (AIEgen) TPE-2SO₃⁻. The polymer could be transformed into a protonated amine-containing polymer after the hydrolysis of maleic acid amide in acidic tumor microenvironment, which would be further self-assembled with TPE-2SO₃⁻ to form aggregated nanoparticles. The transition of TPE-2SO₃⁻ from dispersed state to aggregated state led to an obvious increase in fluorescence intensity due to its AIE characteristics.

Regioregular poly(3-hexylthio)thiopene (P3HTT) has emerged tremendous potential in organic electronic applications due to the strong noncovalent interactions from the sulfur atom linked to thiophene. However, P3HTT generally exhibits low charge mobility mostly due to poor solution processability attributed to dense arrangement of hexylthio side chain in polymer, which led to strong noncovalent interactions among sulfur atoms. To balance the nonvalent interaction and aggregation for P3HTT, herein, we systematically study the effect of hexylthio side chain content in polymer backbone on the structure and properties. A series of regioregular P3HTT-based homopolymers (P3HTT, P3HTT-50, P3HTT-33 and P3HTT-25) were prepared via Kumada catalyst transfer polycondensation method from a set of mono-, bi-, ter- and quarter- thiophenes containing different contents of hexylthio side chain. The DFT calculation shows the planarity of polymers backbone could be improved through reducing the density of hexylthio side chain in polymer mainchain. And significant changes in their crystallinity, aggregation and optical properties were observed with the content of hexylthio side chain reducing. The P3HTT-33 displayed the highest field-effect transistor hole mobility of 2.83×10⁻² cm²·V⁻¹·s⁻¹ resulting from a balance between the crystallinity and planarity. This study demonstrates modulating the content of hexylthio side chain in P3HTT is an effective strategy to optimize the opto-electronic properties of polymer obtaining excellent semiconductor device performance.

Developing new polymeric semiconductors with excellent device performance is essential for organic electronics. Herein, we synthesized two new thiazoloisoindigo (TzII)-based polymers, namely, P(TzII-dTh-dTh) and P(TzII-dTh-dTz), by copolymerizing thiophene-flanked TzII with bithiophene and bithiazole, respectively. Owing to the more electron-deficient nature of bithiazole than bithiophene, P(TzII-dTh-dTz) possesses deeper LUMO/HOMO levels of −3.45/−5.47 eV than P(TzII-dTh-dTh) (−3.34/−5.32 eV). The organic field-effect transistor (OFET) devices based on P(TzII-dTh-dTh) exhibited p-type behaviors with an average hole mobility value as high as 1.43 cm²·V⁻¹·s⁻¹, while P(TzII-dTh-dTz) showed typical ambipolar characteristics with average hole and electron mobilities of 0.38 and 0.56 cm²·V⁻¹·s⁻¹. In addition, we compared the performances of both polymers with other TzII-based polymers reported in our previous work, and showed that the charge carrier polarity can be manipulated by adjusting the number of the thiophene units between the acceptor unit. As the increase of the number of thiophene rings, charge carrier polarity shifts from electron-dominated ambipolar transport to hole-dominated ambipolar transport and then to unipolar hole transport in OFETs, which provides an effective molecular design strategy for further optimization of polymer OFET performance.

The highly efficient method has been developed for the synthesis of NHC·VOCl₃ containing symmetrical or unsymmetrical N-heterocyclic carbene (NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl₃. The total isolated yield of VOCl₃[1,3-(2,4,6-Me₃C₆H₂)₂(NCH=)₂C:] (V4') reached 86% by transmetallation reaction, which is much higher than that (48%) by direct coordination method. This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl₃[PhCH₂NCH=CHNR)C:] (V5’, R = 2,4,6-Me₃C₆H₂; V6’, R = 2,4-Me₂-6-Ph-C₆H₂; V7’, R = 2,6-ⁱPr₂-C₆H₃) with high yield, which could not be obtained by direct coordination method. The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect. The vanadium complex V5’ containing unsymmetrical NHC ligand exhibits higher catalytic activity (3.7×10⁵ g_copolymer·mol⁻¹ of V·h⁻¹) than that of V4' containing symmetrical NHC ligand. Moreover, the higher propylene incorporation ratio (45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5’ than that (39.9%) by using V4'. The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands, affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.

A series of C₁-symmetric ethylene-bridged ansa-(3-R-cyclopentadienyl)(fluorenyl) metallocene complexes (Zr: 1−5; Hf: 6) have been synthesized, characterized and investigated as catalyst precursors for the high temperature ethylene polymerization. Using methylaluminoxane (MAO) as the cocatalyst, zirconium complexes 1−5 bearing a bulky substituent on the 3-position of the cyclopendienyl ring showed high catalytic activities up to 1.48×10⁷ g_PE·mol_Zr⁻¹·h⁻¹ toward the polymerization of ethylene and afforded polyethylenes with high molecular weights (1.49×10⁵−6.31×10⁵ g/mol), meanwhile exhibting great thermal stability at high temperatures up to 120 °C together with a long catalytic life time up to 2 h. By adopting low Al/Zr ratios, such as 125, polyethylenes with ultra high molecular weights up to 2.86×10⁶ g/mol were obtained. It is worthy of noting that zirconium complexes 1−4 bearing a substituent with an aryl pendant showed temperature-dependent activities, which increased rapidly with the increase of polymerization temperature, thus weak interaction of the pendent aryl group with the cationic active center is proposed to account for the very low activities displayed at low temperatures. In contrast to zirconocene complexes 1−5, hafnocene complex 6 only displayed very low catalytic activities toward the polymerization of ethylene and afforded polyethylenes with molecular weights ten times smaller than those obtained by zirconocene complexes 1−5. Zirconocene complexes 1−5 were also able to catalyse the polymerization of propylene at high temperatures, but only afforded waxes with low molecular weights.

A series of Ti(IV) dichloride and dialkoxide complexes with phenoxyimine ligands containing fluorinated and nonfluorinated aliphatic imine fragments have been synthesized. The molecular structures of complexes 1 and 4 were established by single-crystal X-ray diffraction studies. The complexes adopt a distorted octahedral coordination structure around the titanium atom and two oxygen atoms are situated in trans position while two nitrogen atoms and two outgoing ligands (Cl or iPrO) are situated in cis position. Effect of activators (MMAO-12 and combinations Et_nAlCl_3−n + Bu₂Mg) and outgoing ligand (Cl or iPrO) nature on the catalytic activity and properties of the resulting polymers was studied. The Ti complexes, despite the nature of the outgoing ligands (Cl or iPrO) in the presence of Al/Mg activators, was found to display a high ethylene polymerization activity in the range 1600−3830 kg_polymer·mol_Ti⁻¹·h⁻¹·atm⁻¹ with a viscosity average molecular weight (M_v) value in the range 1.1×10⁶−7.1×10⁶ Dalton (Da). The resulting UHMWPE can be processed by a solventless method into high-strength and high-modulus oriented films. The rheological characteristics of a polymer melt have been studied. The absence of a cross-over point did not allow to compare the values of the molecular weight distribution of polymers obtained on fluorinated and non-fluorinated pre-catalysts, however, the estimation of the entanglement density is in good agreement with the mechanical characteristics of oriented films. Upon activation with methylalumoxane, the activity of the complexes decreased very significantly; however, a polymer with a molecular weight of about 12 million Da was obtained. In the process of ethylene/octene-1 copolymerization, fluorine-containing precatalysts showed a clear advantage over non-fluorinated analogues both in activity and in comonomer content.

It is of great significance to design epoxy coatings with superior antibacterial properties and high adhesive properties, as well as excellent processing, superior durability, and high transparency. However, it is still a challenge because of the common complex design and synthesis. Herein, the bio-based monomer protocatechuic acid (PCA) was used as raw material, the catechol structure with high bonding and antibacterial properties was introduced into the flexible alkane segment of ethylene glycol diglycidyl ether (EGDE) through an efficient, and green method, and it was cured with isophorone diamine (IPDA) to prepare corresponding thermosets. The cured resins exhibited excellent all-around qualities, particularly in bonding and antibacterial. When 30% PCA was added to pure epoxy resin, the adhesion between substrate and coating increased from 4.40 MPa to 13.60 MPa and the antibacterial rate of coating against E. coli and S. aureus could approach 100%. All of this is due to the fact that the catechol structure present in PCA has the ability to interact with various substrates and alter the permeability of bacterial cell membranes. The architecture of this method offers a fresh approach to dealing with the issues of challenging raw material selection and complex synthesis techniques.

The emerging biomass-based epoxy vitrimers hold great potential to fulfill the requirements for sustainable development of society. Since the existence of dynamic chemical bonds in vitrimers often reduces both the thermal and mechanical properties of epoxy resins, it is challenging to produce recyclable epoxy vitrimers with both excellent mechanical properties and good thermal stability. Herein, a monomer 4-(((5-(hydroxymethyl)furan-2-yl)methylene)amino)phenol (FCN) containing furan ring with potential to form high density of hydrogen bonding among repeating units is designed and copolymerized with glycerol triglycidyl ether to yield epoxy resin (FCN-GTE), which intrinsically has dual hydrogen bond networks, dynamic imine structure and resultant high performance. Importantly, as compared to the BPA-GTE, the FCN-GTE exhibits significantly improved mechanical properties owing to the increased density of hydrogen bond network and physical crosslinking interaction. Furthermore, density functional theory (DFT) calculation and in situ FTIR analysis is conducted to decipher the formation mechanism of hydrogen bond network. In addition, the FCN-GTE possesses superior UV shielding, chemical degradation, and recyclability because of the existence of abundant imine bonds. Notably, the FCN-GTE-based carbon fiber composites could be completely recycled in an amine solution. This study provides a facile strategy for synthesizing recyclable biomass-based high-performance epoxy vitrimers and carbon fiber composites.

Thermoplastic polycarbonate polyurethanes (PCUs) are multiblock copolymers that have been applied for medical devices for long time. Aliphatic diols are common chain extenders (CE) involved in the composition of the hard segments of PCU. However, limited knowledge was discovered about how the chemical structure of CE affects the hydrogen bonding organization within PCUs and their mechanical properties. To investigate this problem, a group of PCUs were synthesized respectively by extending the polymer chain with 1,4-butanediol (BDO), aminoethanol (MEA), ethanediol (EO) as three kinds of chain extenders. Tiny differences in the CE chemical structure results in remarkable variations in phase separation, condensed morphologies, thermal and mechanical properties, which are characterized by Fourier transform infrared spectrometer, atomic force microscopy, small-angle X-ray scattering, differential scanning calorimetry, and tensile tests. The microstructural evolution during unilateral deformation and the different mechanism induced by the different CEs was probed and unveil by in situ wide- and small-angle X-ray diffraction. Symmetry of CE can improve the organization of the hydrogen bonding. The coherence strength of the urethane/urea group also plays a key role by comparing the two PCUs with ethanediol and aminoethanol.

For the first time, a highly crystalline porous shish-kebab structure with a high degree of crystallinity was obtained by using a combination of two methods for the formation of porous polymeric materials. A treatment procedure using supercritical carbon dioxide (scCO₂) was carried out for oriented ultrahigh molecular weight polyethylene (UHMWPE) films, which provided special conditions for the crystallization of dissolved UHMWPE macromolecules on the surface of oriented UHMWPE crystals. The prepared porous materials were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The particularity of the obtained porous shish-kebab is the absence of the amorphous phase between lamellar crystals (kebabs). The obtained pores had an oval shape, and they were oriented in the orientation direction of the UHMWPE macromolecules. The pore size ranged from 0.05 μm to 4 μm. Controlling the conditions for the crystallization of the UHMWPE macromolecules using supercritical CO₂ gives the possibility to control the size of both lamellar disks and pores formed.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most successful conductive polymers that recently has been used in wearable sensors for human health monitoring. In this work, we prepared a series of PEDOT hybrids consisting of PEDOT, sodium poly(styrene sulfonate) (PSSNa) and polyethylene oxide (PEO), and their preparation could be scaled-up via an adapted solid-state polymerization process. The resistance of the as-prepared PEDOT:PSS/PEO hybrid shows clear temperature response, i.e., it decreases almost linearly with the temperature increase. To understand this phenomenon, the in situ synchrotron radiation wide- and small-angle X-ray scattering (WAXS/SAXS) characterizations were undertaken to study the temperature-dependent microstructure change of the PEDOT:PSS/PEO hybrid. It demonstrated that PEDOT formed conductive paths in the hybrids, which were not destroyed by the PEO crystallization. As temperature increased, the PEO crystals’ melting and the accompanying reorganization of PEDOT chains endowed the hybrid sample temperature responsiveness. Based on these fundamental knowledges, the hybrid materials were used to fabricate flexible wearable sensor that showing temperature sensing performance with an accuracy of 1 °C. These findings shed lights on the scalable manufacturing of wearable sensors for body temperature monitoring.

The chain dynamics heterogeneity of the poly(vinyl butyral) (PVB) plasticized by triethylene glycol bis(2-ethylhexanoate) (TEG-EH) was investigated by various solid-state NMR techniques. The plasticized PVB shows two domains in distinct molecular dynamics differences, namely, rigid and soft domains, where the latter is the plasticizer-rich domain. The time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB, and the results show the decreasing activated energy of components in the soft domain of plasticized PVB (E_a=20.2 kJ/mol) as compared with that of the pristine one (E_a=24.3 kJ/mol). Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific features. The quadrupole-echo ²H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol (VA) units, where only the hydroxyl group of VA is deuterated. The ¹H-¹³C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer, whereas the glass transition temperature differed by approximately 53 °C. This is further supported by Torchia's T₁ relaxation measurements. The origin of such an unusual phenomenon is attributed to the critical role of the remaining VA (~22%) in the soft domain, where the VA units locally aggregate through hydrogen bonding. Also, the existence of a mobility gradient in the VB unit has been demonstrated. Moreover, the mobility difference for VB with different stereo-geometry (meso or racemic conformation) is observed for the first time. This indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic performance of PVB.

The polymer translocation through a nanopore from a donor space (or named cis side) to a receiver space (trans side) in the chaperone-induced crowded environment has attracted increasing attention in recent years due to its significance in biological systems and technological applications. In this work, we mainly focus on the effects of chaperone concentration and chaperone-polymer interaction on the polymer translocation. By assuming the polymer translocation to be a quasi-equilibrium process, the free energy F of the polymer can be estimated by Rosenbluth-Rosenbluth method and then the translocation time τ can be calculated by Fokker-Plank equation based on the obtained free energy landscape. Our calculation results show that the translocation time can be controlled by independently tuning the chaperone concentration and chaperone-polymer interaction at the cis side or the trans side. There exists a critical chaperone-polymer attraction ε^*=−0.2 at which the volume exclusion and interaction effects of the chaperone can balance each other. Additionally, we also find that at large chaperone-polymer attraction, the translocation time is mainly governed by the diffusion coefficient of the polymer.