This article describes central features of the mass transport during the coagulation in water of cellulose–1-ethyl-3-methylimidazoium acetate ([C2mim][OAc]) solutions, namely, that the diffusivities are mainly affected by the relative concentrations of water and [C2mim][OAc], that the concentration of cellulose does not affect diffusivities and coagulation rates, that the diffusivities of low-Mw compounds are similar to those in aqueous [C2mim][OAc] solutions without macromolecules, that the polymer concentration is diluted by the large influx of coagulant causing a positive net mass gain, NMG, from diffusive fluxes, and that such NMG, although observed only as a function in time, is also a function in space that has local peaks significantly higher than the mean NMG value. The conclusion from the first three findings was that the diffusion advances through a liquid phase which possesses a continuous pore network and most of the volume. The precipitated cellulose is concentrated into fibrils whose inhibit...

Diffusion in Ionic Liquid–Cellulose Solutions during Coagulation in Water: Mass Transport and Coagulation Rate Measurements

Regenerated cellulose fibers (RCFs) are an essential type of bio-based chemical fibers. The preparation of RCFs using ionic liquids (ILs) as solvents is an efficient utilization of ecological resources. Investigating the diffusion coefficients during RCFs formation using ILs as solvents is vital due to the potential impact of the interaction between ILs and coagulants on the morphology and properties of RCFs. The determination of diffusion coefficients during RCFs formation is challenging due to its instantaneous and simultaneous nature. For this research, the method and apparatus for measuring the diffusion coefficients during RCFs formation were established, and the diffusion coefficients of various IL and coagulant systems were also explored under different formation conditions. In addition, the relationship between the diffusion coefficient, the formation condition and the self-diffusion coefficient of ILs were investigated using numerical simulation and molecular dynamics simulation. The results demonstrated that the formation conditions, particularly the temperature and composition of coagulants, significantly impact the diffusion coefficient. Lowering the temperature of the coagulants and incorporating ethanol with lower polarity reduced the diffusion coefficient. The diffusion coefficient of [Emim]DEP in the ethanol coagulation bath was 0.79 × 10−9 m2/s at 293 K, which was nearly twice as small as that in the water coagulation bath. These findings were validated by molecular dynamics simulations. Modifying the formation conditions can regulate the structure and properties of the RCFs by affecting the diffusion coefficients during RCFs formation. 

Diffusion coefficients during regenerated cellulose fibers formation using ionic liquids as solvents: Experimental investigation and molecular dynamics simulation

The establishment of facile, efficient, and precise synthetic approaches to selectively convert stable C–H bonds to functional polymers has great significance in both chemistry and material science especially by C(sp3)–H activation. Here, an efficient dual C(sp3)–H activation polymerization of alkynes and activated methylenes catalyzed by Pd(PPh3)4/benzoic acid was successfully established with a 100% atom economy and excellent regio- and stereoselectivity. A series of high-weight-average molecular-weight (Mw of approximately 66,500) poly(aryl butene)s (PABs) with a sole E configuration were generated in remarkable yields (approximately 99%). PABs exhibit good thermal stability, excellent solubility, and great film-forming ability. In addition, the thin PAB films display high refractive indices (RI) of up to 1.7126 at 589 nm. Because this polymerization has a strong functional group tolerance, luminophores can be readily constructed into the main chain to empower PABs with efficient and multicolored luminescence in various states. Notably, PABs containing a tetraphenylethene (TPE) moiety feature unique aggregation-induced emission (AIE) peculiarities, which could specifically and sensitively detect Fe(III) ions with a low limit of detection (LOD) of 1.585 × 10–6 M. 

Ethynyl-Directed Dual C(sp3)–H Activation Polymerization to Construct Regio- and Stereoregular C(sp3)–C(sp3) Bond Polymers

Hyperbranched polymers have been widely applied in various fields because of their good solubility, high reactive end groups, and low viscosity, etc. Therefore, it is of great importance to develop new strategies to build multifunctional hyperbranched polymers with novel architectures. In this work, a C(sp3)‐H activation‐based polymerization of internal alkynes and bifunctional secondary amines is successfully established, and multifunctional hyperbranched polyamines (hb‐PAs) with 100% E‐isomers and high molecular weights (Mw up to 76500) were prepared in good yields (up to 82%). The hb‐PAs containing tetraphenylethylene moiety show unique aggregation‐enhanced emission properties and can be used for explosive detection with a low limit of detection (9.14 × 10−8 M). Notably, the hb‐PAs display high refractive indices (up to 1.7607) that can be further modulated to 1.7825 by the coordination of its peripheral ethynyl group with metallic cobalt. Moreover, the hyperbranched structure endows the hb‐PAs with much better properties than their linear counterparts, such as higher fluorescence quantum yields and refractive indices. In addition, the hb‐PAs can be modified by a C(sp3)‐H activation reaction of internal alkynes and alcohols. This work not only prepares a series of functional nitrogen‐containing hyperbranched polymers but also promotes the application of C(sp3)‐H activation in polymer chemistry.This article is protected by copyright. All rights reserved

Preparation of Multifunctional Regio‐ and Stereo‐regular hb‐Polyamines via C(sp3)‐H Activation‐based Polyamination of Internal Alkynes

The aggregate luminescence behaviors of polymeric luminescent materials have been attracting great attention. However, the importance of the polymerization process on luminescence, namely, polymerization-induced emission (PIE), has rarely been overviewed. In this review, recent advances in polymerization with PIE effects are summarized, including PIE with aromatic rings based on one-/two-/multi-component polymerizations, and PIE without aromatic rings according to disparate mechanisms of polymerizations. Typical examples are selected to elaborate the basic design principles, as well as the properties and potential applications of the luminous polymers. Moreover, the challenges and perspectives in this area are also discussed.

Recent progress on polymerization-induced emission.

Synthesis of fluorescent multisubstituted polyquinolines by cascade C-H activation-based polyannulations of isonicotinamides and diynes

Abstract The coagulation process of nascent fiber of cellulose with ionic liquid 1- allyl-3-methylimidazolium chloride (AMIMCI) as the solvent was studied during drywet spinning. The diffusion rate and the crystallization situation of nascent fiber were tested, its fracture morphology was observed, and the diffusion coefficient D of solvent and the crystallization degree of nascent fiber were calculated according to relevant equations. The diffusion rate and diffusion coefficient of ionic liquid decrease with cellulose concentration increasing in spinning solution and then remain almost the same when the cellulose mass fraction reaches 7%. With the increase of coagulation bath concentration, the diffusion rate and diffusion coefficient of the solvents increase first and then decrease. When the coagulation bath concentration reaches 5%, the diffusion rate and diffusion coefficient of the solvents are at their maximum. With the increase of coagulation bath temperature and the length of air gap, the diffusion rate and diffusion coefficient of ionic liquid increase slightly. The cellulose solution concentration and the spinning air gap have an influence on the crystallization degree of nascent fiber. With the increase of cellulose solution concentration and the spinning air gap, the crystallization degree of the produced nascent fiber increases slightly, but the coagulation bath temperature basically have no influence on the nascent fiber formation.

Study on the coagulation process of cellulose nascent fibers with ionic liquid AMIMCl as a solvent during dry-wet spinning

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Synthesis of fluorescent multisubstituted polyquinolines by cascade C-H activation-based polyannulations of isonicotinamides and diynes

Study on the coagulation process of cellulose nascent fibers with ionic liquid AMIMCl as a solvent during dry-wet spinning