In Situ Synthesis of AIEgen-based Porous Organic Polymer Films by Interfacial Amino-yne Click Polymerization for Efficient Light-Harvesting

We developed a catalyst-free, atom-economical interfacial amino-yne click polymerization to in situ synthesize new aggregation-induced emission luminogen (AIEgen)-based free-standing porous organic polymer films at room temperature. The crystalline properties of POP films were confirmed by powder X-ray diffraction and high-resolution transmission electron microscopy. The good porosity of these POP films was proved by their N₂ uptake experiments. The thickness of POP films can be easily regulated from 16 nm to ≈1 μm by adjusting monomer concentration. More importantly, these AIEgen-based POP films show bright luminescence with high absolute photoluminescent quantum yields up to 37.8 % and good chemical and thermal stability. The AIEgen-based POP film can encapsulate an organic dye (e.g., Nile red) to further form an artificial light-harvesting system with a large red-shift (Δλ=141 nm), highly efficient energy-transfer ability (Φ_ET=91 %), and high antenna effect (11.3).     

Living Alternating Ring-Opening Metathesis Copolymerization of 2,3-Dihydrofuran to Provide Completely Degradable Polymers

2,3-Dihydrofuran (DHF) has recently been gaining significant attention as a comonomer in metathesis polymerization, thanks to its ability to provide the resultant polymer backbones with stimuli-responsive degradability. In this report, we present living alternating copolymerization of DHF with less reactive endo-tricyclo[4.2.2.0^2,5]deca-3,9-dienes (TDs) and endo-oxonorbornenes (oxoNBs). By carefully controlling the reactivity of both the Ru initiators and the monomers, we have achieved outstanding A, B-alternation (up to 98 %) under near stoichiometric DHF loading conditions. Notably, we have also found that the use of a more sterically hindered Ru initiator helps to attain polymer backbones with higher DHF incorporation and superior A, B-alternation. While preserving the living characteristics of DHF copolymerization, as evidenced by controlled molecular weights (up to 73.9 kDa), narrow dispersities (down to 1.05), and block copolymer formation, our DHF copolymers could be broken down to a single repeat unit level under acidic conditions. ¹H NMR analysis of the model copolymer revealed that after 24 hours of degradation, up to 80 % of the initial polymer was transformed into a single small molecule product, and after purification, up to 66 % of the degradation product was retrieved. This study provides a versatile approach to improve the alternation and degradability of DHF copolymers.     

A Facile Strategy for the Development of Recyclable Multifunctional Liquid Crystal Polymers via Post-Polymerization Modification and Ring-Opening Metathesis Polymerization

Post-polymerization modification (PPM) offers a versatile approach for engineering multifunctional polymers, but this advantage has not been fully exploited to fabricate multifunctional liquid crystal polymers (LCPs). Here, we design a facile synthetic approach towards multifunctional LCP by combining the ring-opening metathesis polymerization (ROMP) with PPM, in which ROMP helps to prepare a reactive LCP precursor with high molecular weight, and PPM provides a facilitation to introduce functional groups into the precursor. Consequently, a photo- and humidity-responsive linear LCP (LLCP) is demonstrated to show the potential of this synthetic strategy to diversify functions of the LCPs. Under light irradiation and humidity changes, the deformation modes of the LLCP films are converted to complex shapes (bending, twisting, and curling). The obtained dual-responsive LLCP with high molecular weight possesses excellent processability and recyclability, making it possible to construct 3D shape actuators with programmable deformation behaviors under light/humidity.     

Controlling the Polymer Microstructure in Anionic Polymerization by Compartmentalization

An ideal random anionic copolymerization is forced to produce gradient structures by physical separation of two monomers in emulsion compartments. One monomer (M) is preferably soluble in the droplets, while the other one (D) prefers the continuous phase of a DMSO‐in‐cyclohexane emulsion. The living anionic copolymerization of two activated aziridines is thus confined to the DMSO compartments as polymerization occurs selectively in the droplets. Dilution of the continuous phase adjusts the local concentration of monomer D in the droplets and thus the gradient of the resulting copolymer. The copolymerizations in emulsion are monitored by real‐time ¹H NMR kinetics, proving a change of the reactivity ratios of the two monomers upon dilution of the continuous phase from ideal random to adjustable gradients by simple dilution.     

Tunable Fluorescence from 2D Assemblies of LnW10 and P2W18 Polyoxometalates Clusters with Quaternary Ammonium-type AIEgens

Two-dimensional (2D) AIE-inorganic nanocomposites exhibit high stability and high fluorescence activity. However, limited by the types and properties of 2D inorganic materials, it's challenging to realize complex structures and functions. We designed a quaternary ammonium-type AIE ligand, TPECholine. We chose TPECholine and POM clusters as building blocks and synthesized a series of single-layer nanosheets (SLNSs) by assembling LnW₁₀ or P₂W₁₈ POM clusters with TPECholine. By regulating the types of POM clusters and ligands, the morphology and fluorescence intensity of the SLNSs can be finely tuned. Due to the restriction of the intramolecular motions of AIEgens by the SLNSs, nanosheets can exhibit promoted quantum yield (up to 76 %). In addition, thanks to the sub-nanometric sizes and excess surface charges, SLNSs exhibit excellent solvent compatibility, including water, chloroform, ethanol, etc. And the nanosheets showed high fluorescence intensity in these solvents.     

The Effect of Oxygen on Conversion in the Organic Peroxide-initiated High-Pressure Polymerization of Ethylene

To initiate the high-pressure polymerization of ethylene, oxygen is used together with organic peroxides in a number of tubular reactor processes. Since molecular oxygen is capable of promoting or inhibiting radical polymerization, depending on the reaction conditions chosen, controlled experiments were carried out to clarify these aspects of high pressure ethylene polymerization. In continuous polymerization tests carried out at 1700 bar and temperatures between 110 and 320°C, conversions were determined with tert-amyl perneodecanoate and di-tert-butyl peroxide initiation in the presence of various quantities of oxygen. Batch tests using a photo-initiator together with oxygen were also carried out. A comparison with polymerizations under conditions of careful elimination of oxygen shows no effect on the peroxide-initiated polymerization up to temperatures of 160 to 170°C. Although oxygen is an initiator at higher temperatures, the conversions obtained from the simultaneous addition of controlled quantities of oxygen and organic peroxides is lower than that obtained by adding together the conversions from the separate polymerizations.     

Efficiencies of Various in situ Polymerizations of Liquid Electrolytes and the Practical Implications for Quasi Solid-state Batteries

In situ polymerization of liquid electrolytes is currently the most feasible way for constructing solid-state batteries, which, however, is affected by various interfering factors of reactions and so the electrochemical performance of cells. To disclose the effects from polymerization conditions, two types of generally used in situ polymerizing reactions of ring-opening polymerization (ROP) and double bond radical polymerization (DBRP) were investigated on the aspects of monomer conversion and electrochemical properties (Li⁺-conductivity and interfacial stability). The ROP generated poly-ester and poly-carbonate show a high monomer conversion of ≈90 %, but suffer a poor Li⁺-conductivity of lower than 2×10⁻⁵ S cm⁻¹ at room temperature (RT). Additionally, the terminal alkoxy anion derived from the ROP is not resistant to high-voltage cathodes. While, the DBRP produced poly-VEC(vinyl ethylene carbonate) and poly-VC(vinylene carbonate) show lower monomer conversions of 50–80 %, delivering relatively higher Li⁺-conductivities of 2×10⁻⁴ S cm⁻¹ at RT. Compared two polymerizing reactions and four monomers, the VEC-based F-containing copolymer possesses advantages in Li⁺-conductivity and antioxidant capacity, which also shows simultaneous stability towards Li-metal with the help of LiF-based passivating layer, allowing a long-term stable cycling of high-voltage quasi solid-state cells.     

Emission Control by Molecular Manipulation of Double‐Paddled Binuclear PtII Complexes at the Air‐Water Interface

Molecular functions depend on conformations and motions of the corresponding molecular species. An air–water interface is a suitable asymmetric field for the control of molecular conformations and motions under a small applied force. In this work, double‐paddled binuclear Pt^II complexes containing pyrazole rings linked by alkyl spacers were synthesized and their orientations and emission properties dynamically manipulated at the air–water interface. The complexes emerge from water with concurrent variation of interface orientation of the planes of the Pt^II complexes from perpendicular to parallel during mechanical compression suggesting a unique ‘submarine emission‘. Phosphorescence of the complexes is quenched at the air–water interface prior to monolayer formation with intensities subsequently rapidly increasing during monolayer compression. These results indicate that asymmetric reactions and motions might be controlled by applying mechanical force at the air–water interface.     

聚合物微观结构对聚合物电解质膜性能的影响

聚合物的微观结构是设计具有优异的电化学性能的聚合物电解质膜(PEMs)的基础.在电解质膜中,相分离结构形成的离子簇和离子通道可以影响膜在高温低湿度条件下的离子传导和水的传输,这种结构形成的形貌也可以影响膜的吸水率、溶胀度、碱稳定性等性能.近几年来,人们对于具有微观相分离形貌的PEMs的合成和形貌开展了很多研究.本文主要...     

Preparation of Hydroquinone‐Containing Polymers by ROMP

Polymers containing ortho‐ and para‐hydroquinone moieties 5a,b and 6a are prepared in good yields by ROMP from hydroquinone‐fused norbornadiene derivatives 1a,b and 2a . Oxidation of 5b yielded a quinone derivative 7 , which is evidenced by a strong absorption at 1656 cm^?1 in infrared spectrum.     

Controlling the Microstructure of Conjugated Polymers in High-Mobility Monolayer Transistors via the Dissolution Temperature

It remains a challenge to precisely tailor the morphology of polymer monolayers to control charge transport. Herein, the effect of the dissolution temperature (T_dis) is investigated as a powerful strategy for morphology control. Low T_dis values cause extended polymer aggregation in solution and induce larger nanofibrils in a monolayer network with more pronounced π–π stacking. The field-effect mobility of the corresponding monolayer transistors is significantly enhanced by a factor of four compared to devices obtained from high T_dis with a value approaching 1 cm² V⁻¹ s⁻¹. Besides that, the solution kinetics reveal a higher growth rate of aggregates at low T_dis, and filtration experiments further confirm that the dependence of the fibril width in monolayers on T_dis is consistent with the aggregate size in solution. The generalizability of the T_dis effect on polymer aggregation is demonstrated using three other conjugated polymer systems. These results open new avenues for the precise control of polymer aggregation for high-mobility monolayer transistors.     

Tetrabutylammonium Halides as Selectively Bifunctional Catalysts Enabling the Syntheses of Recyclable High Molecular Weight Salicylic Acid-Based Copolyesters

To synthesize high molecular weight poly(phenolic ester) via a living ring-opening polymerization (ROP) of cyclic phenolic ester monomers remains a critical challenge due to serious transesterification and back-biting reactions. Both phenolic ester bonds in monomer and polymer chains are highly active, and it is difficult so far to distinguish them. In this work, an unprecedented selectively bifunctional catalytic system of tetra-n-butylammonium chloride (TBACl) was discovered to mediate the syntheses of high molecular weight salicylic acid-based copolyesters via a living ROP of salicylate cyclic esters (for poly(salicylic methyl glycolide) (PSMG), M_n=361.8 kg/mol, Ð<1.30). Compared to previous catalysis systems, the side reactions were suppressed remarkably in this catalysis system because phenolic ester bond in monomer can be selectively cleaved over that in polymer chains during ROP progress. Mechanistic studies reveal that the halide anion and alkyl-quaternaryammonium cation work synergistically, where the alkyl-quaternaryammonium cation moiety interacts with the carbonyl group of substrates via non-classical hydrogen bonding. Moreover, these salicylic acid-based copolyesters can be recycled to dimeric monomer under solution condition, and can be recycled to original monomeric monomers without catalyst under sublimation condition.     

Synthesis of Stereocontrolled Degradable Polymer by Living Cascade Enyne Metathesis Polymerization

A stereocontrolled degradable polymer was synthesized via living cascade enyne metathesis polymerization. Highly stereodefined N,O-acetal-containing enyne monomers were prepared using the Pd-catalyzed hydroamination of alkoxyallenes and ring-closing metathesis. The resulting chiral polymer exhibited a narrow dispersity window. Block copolymers were prepared not only by sequentially adding nondegradable and degradable monomers but also by using enantiomerically different monomers to produce stereocontrolled blocks. Owing to the hydrolyzable N,O-acetal moiety in the backbone structure, the resulting polymer could degrade under acidic conditions generated using various acid concentrations to control the degradation. Additionally, the aza-Diels–Alder reaction modified the polymer without losing the stereochemistry.     

In Vitro Light-Up Visualization of a Subunit-Specific Enzyme by an AIE Probe via Restriction of Single Molecular Motion

Enzymes contain several subunits to maintain different biological functions. However, it remains a great challenge for specific discrimination of one subunit over another. Toward this end, the fluorescent probe TPEMA is now presented for highly specific detection of the B subunit of cytosolic creatine (CK) kinase isoenzyme (CK-B). Owing to its aggregation-induced emission property, TPEMA shows highly boosted emission toward CK-B with a fast response time and very low interference from other analytes, including the M subunit of CK (CK-M). With the aid of a Job plot assay, ITC assay and molecular dynamics simulation, it was directly confirmed that the remarkably enhanced fluorescence of TPEMA in the presence of CK-B results from the restriction of single molecular motion in the cavity. Selective wash-free fluorescence imaging of CK-B in macrophages under different treatments was successfully demonstrated.     

Advanced Surfaces by Anchoring Thin Hydrogel Layers of Functional Polymers

Surface design and engineering is a critical tool to improve the interaction of materials with their surroundings. Immobilization of soft hydrogels is one of the attractive strategies to achieve surface modification. The goal of this review is to provide a comprehensive overview of the different strategies used for surface tethering of hydrogel layers via crosslinking immobilization of pre-fabricated functional polymers. In this strategy, crosslinkable polymers are first prepared via various polymerization techniques or post-functionalization of polymers. Afterwards, the crosslinkable polymers are attached or tethered on the surfaces of substrates using a variety of approaches including photo-crosslinking, click reactions, reversible linkages, etc. For each case, the principles of hydrogel tethering have been explained in detail with representative examples.Moreover, the potential applications of the as-modified substrates in specific cases have also been addressed and overviewed.     

Controlling the Microstructure of Conjugated Polymers in High‐Mobility Monolayer Transistors via the Dissolution Temperature

It remains a challenge to precisely tailor the morphology of polymer monolayers to control charge transport. Herein, the effect of the dissolution temperature (T_dis) is investigated as a powerful strategy for morphology control. Low T_dis values cause extended polymer aggregation in solution and induce larger nanofibrils in a monolayer network with more pronounced π–π stacking. The field‐effect mobility of the corresponding monolayer transistors is significantly enhanced by a factor of four compared to devices obtained from high T_dis with a value approaching 1 cm² V^?1 s^?1. Besides that, the solution kinetics reveal a higher growth rate of aggregates at low T_dis, and filtration experiments further confirm that the dependence of the fibril width in monolayers on T_dis is consistent with the aggregate size in solution. The generalizability of the T_dis effect on polymer aggregation is demonstrated using three other conjugated polymer systems. These results open new avenues for the precise control of polymer aggregation for high‐mobility monolayer transistors.     

Solvent-Polymer Interaction. II. Measurements of Liquid Solvent Molecules Associating with Polymer Sites and of Their Transport Behavior in Polymer Membrane by Thermogravimetry,GLC, and Mass Spectrometry

The measurement of sorption and diffusion behavior of liquid ethanol and water solvent mixtures in polyurethane membrane were made simultaneously by thermogravimetry. The individual amounts of sorbed water and ethanol in the polymer membrane were estimated by thermogravimetry and differentiated by mass spectrometry. In addition, from a single dynamic thermogravimetric experiment the activation energy for solvent molecules desorbing from the polymer membrane was also determined. The thermodynamic activity of ethanol vapor in equilibrium with the ethanol-water-polyurethane system was determined by gas-liquid chromatography. The clustering functions, the mean numbers of solvent molecules in the clusters, and those associating with polymer sites were evaluated by applying simplified mathematical derivatives using the experimentally determined values of activity and volume fraction of solvent molecules. It was found that at lower ethanol concentration the tendency for ethanol molecules to cluster together is high. At higher ethanol activity, ethanol-polymer site interactions predominantly occurred.

Similar results were observed for ethanol-water molecules. However, water molecules in this particular system did not exhibit a self-associating tendency nor interact with the polymer sites. It was concluded that the Zimm-Lundberg clustering theory can be adequately applied to the interpretation of sorption and diffusion behavior of liquid ethanol-water mixtures in the polymer membrane.     

Hydration-Facilitated Fine-Tuning of the AIE Amphiphile Color and Application as Erasable Materials with Hot/Cold Dual Writing Modes

Hydration water greatly impacts the color of inorganic crystals, but it is still unknown whether hydration water can be utilized to systematically manipulate the emission color of organic luminescent groups. Now, metal ions with different hydration ability allow fine-tuning the emission color of a fluorescent group displaying aggregation induced emission (AIE). Because the hydration water can be removed easily by gentle heating or mechanical grinding and re-gained by solvent fuming, rewritable materials can be fabricated both in the hot-writing and cold-writing modes. This hydration-facilitated strategy will open up a new vista in fine-tuning the emission color of AIE molecules based on one synthesis and in the design of smart luminescent devices.     

AIE荧光聚合物RAFT可控合成与表征及光物理性质研究

聚集诱导发光(AIE)分子是与传统的聚集态荧光淬灭染料分子具有截然相反的光物理性质的新型有机发光材料,可广泛应用于化学/生物传感、生物探针与成像、诊疗一体化和光电子器件等诸多领域中。本论文通过可逆加成-断裂链转移(RAFT)聚合方法,可控合成了侧链型四苯乙烯TPE聚丙烯酸酯AIE聚合物。通过实验条件的优化与探索,尤其采用半衰期较短、活性更高的偶氮二异庚腈(ABVN)取代常规的偶氮二异丁腈(AIBN)引发剂,将原来超过12 h的过夜反应前沿科研实验,改造为较短的3–5 h聚合反应时间内即可达到中等收率和较好的聚合物产品质量,使其成为一个适合本科教学环境的新创实验。本实验融合了无水无氧操作技术、柱层析分离纯化、RAFT可控聚合和GPC分子表征技术、FTIR、NMR、UV-Vis、荧光光谱等多种现代实验技术和表征方法,考查了所合成四苯乙烯TPE侧基的AIE聚合物的光物理性质,测定其溶液中的相对荧光量子产率达17%。     

Recent Developments in the Surface Modification of Polymers

Summary. Selected trends and scientific achievements in the surface modification of polymers are reported. In this context, both UV-light triggered free radical polymerization-based techniques relevant to industrial processes and ring-opening metathesis polymerization-based chemistry, relevant for the manufacture of specialty materials, are addressed.