Chemical Research in Chinese Universities

Chemical Research in Chinese Universities Vol.39 No.5 October 2023

2023, 39(5): 0-0.

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Role of Conformational Entropy in Complex Macromolecular Systems

DAI Xiaobin, WAN Hai-Xiao, ZHANG Xuanyu, WEI Wenjie, CHEN Wenlong, ZHANG Longgui, LI Juan, YAN Li-Tang

2023, 39(5): 709-718. doi:10.1007/s40242-023-3174-2

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Conformation is the key to revealing the physical characteristics of macromolecular systems and receives tremendous interest from the fields of polymer physics and biological materials. The conformational entropy, related to the number of conformations of the macromolecule, plays a predominant role in the structural formation, transition, and dynamics of macromolecular systems. In this review, we present a comprehensive overview of the research, development and applications of the conformational entropy in complex macromolecular systems. We begin by discussing the physical origin of the conformational entropy based on statistical mechanics of macromolecules in classical polymer physics, and then introduce the recent progress on the predictive modeling of the conformational entropy, associated with a variety of typical macromolecular systems. Furthermore, we also highlight several principles and rules, which have been harnessed to manipulate the structural organization of complex macromolecular systems through the conformational entropy. We anticipate that this review will further promote fundamental research in polymer physics, and offer intriguing prospects for applications in complex macromolecular systems including biomacromolecules, grafted nanoparticles, and polymer nanocomposites.

Recent Advances in Helical Polyisocyanide-based Block Copolymers: Preparation, Self-assembly and Circularly Polarized Luminescence

ZHOU Li, CHEN Kun, ZHOU Xing-Yu, WU Zong-Quan

2023, 39(5): 719-725. doi:10.1007/s40242-023-3170-6

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Polyisocyanides and their block copolymers have widespread applications in many fields due to their unique helix and self-assembly properties. At first, the latest progress in the preparation of helical polyisocyanide-based block copolymers via the method of one-pot sequential controlled synthesis and stepwise polymerization was highlighted in this minireview. Various categories of helical polyisocyanide-based copolymers including amphiphilic block copolymers, UV-response block copolymers, π-conjugated block copolymers, etc., have been prepared successfully. Moreover, recent advances in the self-assembly and circularly polarized luminescence performance of amphiphilic and π-conjugated helical polyisocyanide-based copolymers have been introduced, respectively. We hope this minireview will not only inspire more interest in developing helical polyisocyanide-based copolymers, but also encourage further progress in the field of building artificial functional materials.

A “Catalyst+Support” Strategy for Salicylaldimine Nickel Catalyzed Ethylene Polymerization and Copolymerization with Polar Monomers

WANG Zihao, YANG Lei, XU Mengli, TAN Chen, CHEN Changle

2023, 39(5): 726-730. doi:10.1007/s40242-023-3104-3

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Packing Adjustment Towards High Mobility Luminescent Conjugated Polymers

ZHANG Yihan, LIU Qingqing, GAO Can, XIE Ziyi, HU Beining, DONG Huanli

2023, 39(5): 731-735. doi:10.1007/s40242-023-3180-4

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Next generation display and lighting technology calls for thinner, cheaper and more-flexible unit devices. Polymer light emitting transistor (PLET), which integrates logic function of organic field effect transistor (OFET), luminescence function of organic light emitting diode (OLED), and potential mechanical properties, is believed to be the raising star in this field. However, great challenges remain in developing the core materials of PLETs, which simultaneously require the integration of high ambipolar mobility and strong solid-state luminescence properties. Herein, high mobility luminescent thienopyrroledione-benzodiathiadiazole-fluorene-based conjugated polymer was chosen as polymer backbone, and polymers TBT-1 and TBT-2 (TBT=thienopyrroledione-benzodiathiadiazole-thienopyrrole-dione) with red luminescence were obtained by direct arylation polymerization (DArP). By introducing linear alkyl side chains, the packing orientation is changed from face-on in TBT-1 thin film to edge-on in TBT-2 thin film, which is beneficial for improving the field effect performance. The average hole and electron mobility of TBT-2 are 1.1×10^-2 and 2.0×10^-3 cm²·V^-1·s^-1, respectively. This work provides new design strategy for high mobility luminescent conjugated polymers, which can be used in PLETs.

A General Approach for Synthesis of Circularly Assembled Supramolecular Polymers by Means of Region-confined Amphiphilic Supramolecular Polymerization

ZHANG Lei, ZHANG Chenyang, MIN Jing, LIU Chenglong, MAO Shizhong, WANG Liyan, YANG Bing, DONG Zeyuan

2023, 39(5): 736-740. doi:10.1007/s40242-023-3153-7

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Topological supramolecular polymers are responsible for design of innovative materials with unique physical properties but remain a challenging task to prepare by means of supramolecular polymerization. In this contribution, we present a novel method of region-confined amphiphilic supramolecular polymerization (RASP) in a controllable two-step self-organization pathway, which was certified by a new type of pyridine-oxadiazole alternating 48-membered macrocycles with structurally regional distribution of distinct self-assembling groups that can self-organize into circular supramolecular architectures. Meanwhile, water molecule plays a crucial role in RASP, and the water content in nonpolar solvent chloroform is sensitive to trigger controllable amphiphilic self-organization. Moreover, differing from the traditional rodlike micelles formed by self-assembly of linearly amphiphilic molecules, this approach of RASP exclusively gives rise to the formation of circularly assembled supramolecular polymers.

Stress Transfer in Polymer Nanocomposites: A Coarse-grained Molecular Dynamics Study

GUAN Junlei, SUN Zhaoyan

2023, 39(5): 741-749. doi:10.1007/s40242-023-3176-0

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In this work, we used coarse-grained molecular dynamics simulation methods to investigate the dispersion and percolation behavior of nanoparticles in polymer nanocomposite. Our aim was to investigate the correlation between particle arrangement in nearby layers and the stretching performance in composite systems by exploring the stress transfer processes during different stages of the stretching process. The machine learning technique of linear regression was used to quantitatively measure the efficiency of stress transfer between particles nearby. According to our research, increasing the strength of attraction can significantly enhance the particle dispersion and affect the percolation threshold. We also noticed a non-monotonic relationship between the interaction strength and the tensile stress. Additionally, we quantified the efficiency of nanoparticles and polymers at transferring stress to nearby nanoparticles. As a result, the stress value provided by each particle in the aggregation body is significantly increased by the aggregation behavior of nanoparticles. The non-monotonic behavior is caused by two variables:the rapid disintegration of aggregates and the improved stress transfer efficiency from polymers to nanoparticles. Significantly, it was discovered that the structural rearrangement of nanoparticles during stretching is the main reason that causes the yield-like behavior seen in poorly dispersed systems.

High Performance Polylactide Toughened by Supertough Polyester Thermoplastic Elastomers: Properties and Mechanism

FENG Songyang, ZHAO Wuchao, HE Jianghua, ZHANG Yuetao

2023, 39(5): 750-756. doi:10.1007/s40242-023-3160-8

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It is a challenge to develop a biodegradable toughener to toughen polylactic acid (PLA) with both high strength and high toughness, since toughness and strength are mutually exclusive. Here, a series of supertough polyester thermoplastic elastomers (TPEs), poly(L/D-lactide)-b-poly(ε-caprolactone-co-δ-valerolactone)-b-poly (L/D-lactide)s (PLLA-PCVL-PLLA, L-TPEs or PDLA-PCVL-PDLA, D-TPEs), were prepared and blended with a PLLA matrix to toughen PLLA. The mechanical properties of PLLA could be regulated in a wide range by changing blending ratios and TPE structures. For PLLA blends toughened by L-TPEs, the highest elongation at break is up to 425% with the tensile strength of 33.1 MPa and the toughness of 104 MJ/m³. By the stereocomplex crystallization of PLA (sc-PLA), the tensile strength of the PLLA/D-TPE blends further increased to 41.8 MPa with a similar elongation at break (418%) and the toughness up to 128 MJ/m³. The detailed characterizations revealed a toughening mechanism:(I) the added soft segments increased the ductility of the PLLA matrix, (II) the PLLA segments of L-TPEs increased the compatibility between TPEs and PLLA matrix, and (III) the formation of sc-PLA between the PDLA segments in D-TPE and PLLA provided higher tensile strength by enhancing the strength of the crystal skeleton. The toughened PLA using TPEs can maintain original non-toxic and degradable properties, and be applied potentially in surgical sutures, and 3D-printed scaffolds.

Visible Light-driven Self-healable Mechanochromic Polyurethanes

HAN Jinpeng, YUAN Yuan, CHEN Yulan

2023, 39(5): 757-762. doi:10.1007/s40242-023-3118-x

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Polyurethanes incorporating spiropyran (SP) and diselenide (DiSe) in the main chain, which are confined in different hard segments are developed. Visible light-driven diselenide metathesis and mechanically induced ring opening of SP offer self-healing and mechanochromic properties of the polymers, respectively. Delicate selection of the polymer backbone is found essential to promote the dual functions. In particular for polyurethane with SP coupled into 4,4'-methylenebis(cyclohexyl isocyanate) and DiSe linked with isophorone diisocyanate, excellent mechanical, mechanochromic and self-healing properties are estimated. Moreover, combining self-healing and self-reporting moieties in one chain allows the discrimination of different healing mechanisms, including bond formation and chain entanglement, in a visualized way.

Non-conjugated Polynorbornene Hosts with High Triplet Energy Levels for Solution-processed Narrowband Blue OLEDs

LI Qiang, CHEN Liang, WANG Xingdong, WANG Shumeng, SHAO Shiyang, WANG Lixiang

2023, 39(5): 763-771. doi:10.1007/s40242-023-3167-1

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Three polymer hosts (namely PNB-tBuCz, PNB-Ac, PNB-TAc) containing non-conjugated polynorbornene (PNB) backbone and hole-transporting arylamine segments (carbazole, acridan and dendritic teracridan) in side chains are developed for solution-processed narrowband blue organic light-emitting diodes (OLEDs). It is found that the non-conjugated polynorbornenes can keep high triplet energy (E_T) levels in range of 3.12-3.20 eV by interrupting the conjugation of repeating units, making them capable as host materials for blue emitters. Meanwhile, by increasing the electron-donating capability of side chain arylamine from carbazole to acridan and dendritic teracridan, the highest occupied molecular orbital (HOMO) levels for the polymer hosts are elevated from -5.50 eV to -5.11 eV, beneficial for reducing the hole injection barrier from anode to emissive layer. As a result, solution-processed OLEDs employing polynorbornenes with dendritic teracridan side chain (PNB-TAc) as host and boron, selenium, nitrogen-containing multiple resonance thermally activated delayed fluorescence emitter as dopant reveal efficient narrowband blue electroluminescence with emission peak at 474 nm, full-width at half maximum of 30 nm, together with maximum external quantum efficiency of 20.2%, representing the state-of-the-art device efficiency for solution-processed OLEDs with narrowband blue emission.

DFT-supported Mechanistic Understanding of the Ring-opening Polymerization of Cyclic Trithiocarbonates Mediated by Organic Base

WANG Xinjie, REN Baihao, ZHAO Jinzhuo, YUE Tianjun, KANG Xiaohui, REN Weimin

2023, 39(5): 772-776. doi:10.1007/s40242-023-3034-0

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Sulfur-rich polymers are endowed with several enhanced features, such as high refractive index and excellent thermal and mechanical properties, owing to the incorporation of sulfur atoms into the polymer main chain. As an important category of sulfur-rich polymers, polytrithiocarbonates can be efficiently synthesized through ring-opening polymerization (ROP) of cyclic trithiocarbonates (CTCs) mediated by 1,5,7-triazabicyclo[4.4.0] dec-5-ene (TBD) and benzyl mercaptan (BnSH). However, the mechanistic investigations of this reaction are limited. In this study, we attempted to understand this reaction by simulating chain initiation, propagation, and termination in the ROP of CTCs using density functional theory (DFT) calculations. As demonstrated, the acceleration of the ROP of δ-CTC by BnSH can be attributed to the smaller size of BnS^- compared to TBD when nucleophilic attacking, and [TBDH]⁺ enhancing the interaction with the monomer and stabilizing the generated active species in the initiating process. In addition, the ability of BnSH to tune the topological structures of the final polymers is ascribed to the suppressed transesterification between the thiolate species and the first trithiocarbonate unit initiated by BnS^-. Furthermore, the limitations that hinder the ROP of five- and six-membered CTCs under general conditions are the unfavored thermodynamic factors, wherein the ROP of six-membered CTC is possible below -75 ℃.

Phototriggered Formation of a Supramolecular Polymer Network Based on Orthogonal H-Bonding and Host-Guest Recognition

BAI Ruixue, YANG Xue, ZHAO Jun, ZHANG Zhaoming, YAN Xuzhou

2023, 39(5): 777-781. doi:10.1007/s40242-023-3056-7

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Supramolecular polymer networks (SPNs) have gained increasing research attention due to their reversible and tunable nature in the preparation of adaptive materials. The use of hierarchical self-assembly techniques is an emerging strategy for the fabrication of smart supramolecular polymer networks, but corresponding study is still rare. Herein, we have reported a novel supramolecular polymer network through complementary host-guest interactions and phototriggered quadruple H-bonding cross-linking. Specifically, we design and synthesize an H1G1-type monomer consisting of a benzo-21-crown-7 (B21C7) host (H1), a dialkylammonium salt guest (G1) and a photolabile o-nitrobenzyl ether protected ureidopyrimidinone (Upy) moiety. B21C7 and ammonium moieties can first form a linear supramolecular polymer through complementary host-guest interactions. Under photoirradiation, the Upy groups on the SP side chains were released, and the obtained linear supramolecular polymer could be further transformed into SPN through a quadruple H-bonding cross-linking. Meanwhile, the in situ transformation in the solid state is also accompanied by pronounced enhancement in mechanical properties, which provides foundation for further application of materials in different scenarios.

Introduction and Influence of Water in the Preparation of Crosslinked PVC Foam by Isocyanate

BI Xiang, LI Minggang, LU Min, YOU Jiangan, XUE Jian, YU Haihui, JIANG Zhiwei, TANG Tao

2023, 39(5): 782-789. doi:10.1007/s40242-023-3067-4

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In the preparation process of crosslinked polyvinyl chloride (c-PVC) foam by isocyanate, the formulated mixture is generally required to be carried out under the condition of isolated water, so as to avoid the mixing difficulties caused by the reaction between the introduced water and isocyanate. In this paper, NaHCO₃ was added to the mixture to indirectly introduce water into the system, and the effects of NaHCO₃ on the cell structure and curing time of c-PVC foam were investigated. The results showed that NaHCO₃ not only played a role of foaming agent, but also was a good nucleating agent for cells. At the same time, the introduction of NaHCO₃ held back the exudation of modified diphenylmethane-4,4'-diisocyanate (MDI) on the cell wall. The effects of NaHCO₃ on the cell structure and aggregation structure of c-PVC foam were studied by thermogravimetric analysis, infrared spectroscopy and scanning electron microscopy. The results showed that decomposition of NaHCO₃ occurred during the molding stage, which made small amount of MDI react with water to form polyurea, improved the compatibility of MDI with PVC and inhibited the exudation of MDI.

Oxygen/Sulfur Atom Exchange Copolymerization of Carbon Disulfide and Propylene Oxide by a Highly Effective Heterogeneous Berlin Green Catalyst

Munir Ullah KHAN, Safir Ullah KHAN, CAO Xiaohan, Muhammad USMAN, Muhammad Naeem SHAH, Abdul GHAFFAR, Muhammad HASSAN, ZHANG Chengjian, ZHANG Xinghong

2023, 39(5): 790-796. doi:10.1007/s40242-023-3144-8

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In this study, we report that Berlin Green (FeFe-BG) framework exhibits superior performance in the catalytic coupling of carbon disulfide (CS₂) and propylene oxide (PO) to generate a random copolymer containing thioether, propylene monothiocarbonate and ether units. Oxygen and sulfur atom exchange was detected in polymeric and cyclic thiocarbonate byproducts and utilized to modulate the copolymerization of CS₂ and propylene oxide. The coupling of PO and CS₂ was selective for copolymer formation under various reaction conditions. ¹H and ¹³C NMR spectroscopy determined two distinct polymer linkages and two cyclic byproducts. Copolymer number average molecular weights ranged from 6.4 kg/mol to 10.5 kg/mol, with a comparatively low polydispersity of 1.3-1.7. The CS₂/PO molar feed ratio had a significant impact on the O/S exchange process; the ratio of cyclic thiocarbonate byproducts could be efficiently regulated by tuning the CS₂ molar feed ratio.

Macrocyclic Binuclear α-Diimine Nickel Catalysts for Ethylene Polymerization

YANG Jingshuang, ZHANG Yuxing, JIAN Zhongbao

2023, 39(5): 797-802. doi:10.1007/s40242-023-3149-3

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Polyolefins are globally important plastics. Molecular weight and molecular weight distribution are two key parameters for determining the properties of polyolefin materials. In this contribution, we develop a strategy for combining the macrocyclic framework and the binuclear effect into the benchmark α-diimine late transition metal catalysts, and thus macrocyclic binuclear α-diimine nickel catalysts (Ni₂-Me and Ni₂-iPr) are prepared. Compared to the classical Brookhart's acyclic mononuclear α-diimine nickel analogues (Ni₁-Me and Ni₁-iPr), these nickel catalysts exhibit enhanced thermostability (up to 110℃) and produce polyethylenes with higher molecular weights (up to 7 times) and lower branching densities (as low as 9 branches/1000C) in methylaluminoxane (MAO) activated ethylene polymerization. This translates into the ability of the catalyst to afford more linear high molecular weight polyethylenes. In particular, bimodal polyethylenes with broad molecular weight distributions (M_w/M_n=8.08-14.66) are generated by the sole catalyst. This work affords diverse polyethylenes.

Multiple Responsive Photonic Prints Through Localized Interpenetrating Polymer Network

ZHANG Tian, JIA Xiaolu, HOU Zaiyan, XIE Ge, ZHANG Lianbin, ZHU Jintao

2023, 39(5): 803-808. doi:10.1007/s40242-023-3154-6

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Multiple responsive photonic prints that can be revealed by a thermal or light stimulus are prepared by locally producing interpenetrating polymer network (IPN) within photonic hydrogels. Thermo-responsive poly-(N-isopropylacrylamide) (PNIPAM) photonic hydrogels with self-assembled monodisperse carbon-encapsulated Fe₃O₄ nanoparticles (Fe₃O₄@C NPs) are first prepared by a photopolymerization process. Then photopolymerization of acrylamide (AM) is carried out within the photonic hydrogel with the help of a mask to generate an IPN structure locally. Because of the regionally different network structure and the resulting varied responsiveness, responsive photonic prints are obtained. Due to the thermo-responsive capability of the PNIPAM and the photothermal conversion capability of the incorporated Fe₃O₄@C NPs, the as-prepared photonic prints with a localized IPN structure can shift the structural color in a broad spectrum range under thermal or light stimuli. The current multiple responsive photonic prints with a localized IPN structure can realize full-color pattern display under thermal and light stimulations, providing a new path for anti-counterfeiting, display, and information encoding.

Functionalizable and Recyclable Aliphatic Polycarbonates Derived from Biomass Feedstocks and CO₂

WU Yanchen, FAN Huazhong, SHAN Siyi, WANG Siqi, CAI Zhongzheng, ZHU Jian-Bo

2023, 39(5): 809-815. doi:10.1007/s40242-023-3165-3

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Two bio-based seven-membered cyclic carbonate monomers M1 and M2 were synthesized in three steps from myrcene, which could produce polycarbonates via ring-opening polymerization using metal or organic catalysts. The functionalizable olefin moieties in resulting polycarbonates have driven post-polymerization modifications via radical cross-linking and hydrogenation, enabling the resulting polymers with tunable thermal properties. More importantly, the chemical recycling of P(M)s was achieved through "monomer → polymer ⇄ dimer", which presented a platform for the synthesis of chemically recyclable biobased polycarbonates.

Dispersity Regulation in Photo-controlled Radical Polymerization by Merging Aryl Sulfonyl Chloride Initiators and Mixed Disulfide Agents

ZHANG Lu, ZHANG Zexi, CHEN Mao

2023, 39(5): 816-821. doi:10.1007/s40242-023-3171-5

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On-demand regulation of molecular weight distribution (MWD) is crucial to influence the properties of polymers. In this work, we reported an organocatalyzed photo-controlled radical polymerization (photo-CRP) from the tosyl chloride initiator by combining two disulfides as chain transfer agents. This novel synthetic protocol allows facile access toward well-defined polymers with tunable MWDs and predetermined molecular weights. Experiments including structural characterization, kinetic investigation and chain-extension polymerization exhibited good chain-growth control for polymers of different dispersities. Given the easy accessibility of the initiating site (sulfonyl chloride) on many aromatic sources, this work presents a promising avenue to modify such substances with polymers of tailored MWDs, chain lengths and repeating units under metal-free and mild conditions driven by light.

Stoichiometric Imbalance-promoted Step-growth Polymerization Based on Self-accelerating Three-component Reaction

ZHANG Yu, ZHENG Jianzhi, LI Xijuan, WU Ying, ZHANG Ke

2023, 39(5): 822-828. doi:10.1007/s40242-023-3173-3

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Aself-accelerating three-component reaction was developed using the secondary amines, CS₂, and sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DIBOD) as reactants. In this three-component reaction, the secondary amine reacts with CS₂ to form dithiocarbamate anion, which subsequently in-situ reacts with DIBOD behaving a self-accelerating reaction property. Specifically, the reaction of dithiocarbamate anion with the first alkyne of DIBOD activates the unreacted alkyne, which reacts with dithiocarbamate anion much faster than the original alkyne of DIBOD. Using the self-accelerating three-component reaction as polymerization reaction, a stoichiometric imbalance-promoted step-growth polymerization method was developed using the difunctional secondary amines, CS₂, and DIBOD as monomer groups. This novel three-component polymerization can quickly produce high molecular weight dithiocarbamate-containing polymers under mild conditions using a slight molar excess of DIBOD to difunctional secondary amine monomer. Containing sulfur elements in the backbones, the resultant polymers hold high refractivity and may find potential applications in optical and optoelectronic fields.

Molecular Insights into Distinct Membrane-insertion Behaviors and Mechanisms of 20 Amino Acids: an All-atom MD Simulation Study

TU Wenqiang, DONG Xuewei, OU Luping, ZHANG Xinke, YUAN Bing, YANG Kai

2023, 39(5): 829-839. doi:10.1007/s40242-023-3175-1

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Interfacial interactions of proteins with cell membranes play important roles in fundamental physiological processes of cells. The binding of proteins to membranes involves interactions between amino acids and membranes. However, the mechanism underlying amino acids' membrane behavior remains elusive. Herein, all-atom molecular dynamic simulations were applied to comprehensively investigating the molecular details of interactions between 20 amino acids with DOPC membranes. Our results show that 20 amino acids exhibit distinct membrane insertion activities, which are not simply determined by the side chain properties of amino acids. Aromatic Tyr/Phe/Trp, hydrophobic Val/Ile/Leu/Met, positively-charged Arg and hydrophilic Cys exhibit significantly strong membrane insertion capacities with different characteristic insertion depths and insertion angles. Surprisingly, hydrophobic Ala, positively-charged His/Lys, hydrophilic Asn/Ser/Gln/Thr, negatively-charged Asp/Glu and Pro/Gly have low membrane insertion capabilities. Considering the chemical structures and interaction details of amino acids with membranes, we suggest that the abundance and diversity of interaction sites and types, the synergistic effect of hydrophilic and hydrophobic interactions of amino acids with membranes and the structural flexibility of amino acids are key factors for determining membrane insertion capabilities and characteristics of amino acids. Our study sheds light on the atomic mechanism of interactions between single amino acids and membranes.

Understanding the Conformational Interconversions of a Polymer Chain in a Liquid Environment at the Single-molecule Level

SHAO Yue, WEI Junhao, BAO Yu, CAI Wanhao, QIAN Lu, CUI Shuxun

2023, 39(5): 840-844. doi:10.1007/s40242-023-3087-0

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The conformational interconversions of polymer chains have been of great interest as a basic scientific issue. Single-molecule force spectroscopy (SMFS) is a powerful tool for molecular manipulation, which enables experimental studies on the single-chain behaviors of polymers. The SMFS results show that an individual polymer chain in a liquid environment may have similar properties to an ideal chain, which contradicts the traditional theoretical view. Herein, by taking into account the collisions of solvent molecules, the conformational interconversions of a single polymer chain in a liquid environment have been analyzed. The conformational interconversion frequency of a carbon-carbon bond of an alkane chain can be estimated by establishing the relationship between the internal rotation barriers of small molecules (monomers) and the corresponding macromolecules. Since the time scale of conformational interconversions of the polymer backbone is much shorter than that of SMFS experiments, most polymers with C-C backbones behave as ideal chains in liquid environments.

Multi-fluorous-included Counter Anions-based Ionic Copolymers: Synthesis and Enhanced Hydrophobic Adsorption Films on Copper Surface for Super Protection

REN Weihua, SHI Yueting, CHEN Lingli, YANG Song, ZHANG Shengtao, LIU Xiaohong, REN Xiaolei, LI Hongru

2023, 39(5): 845-856. doi:10.1007/s40242-022-2276-6

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Three multi-fluorous-carried anions-based ionic copolymers (ICs) including (fluorosulfonyl)imide (FSI^-), (trifluorometha-nesulfonyl)imide (TFSI^-) and hexafluorophosphate anions (PF₆^-) (IC[FSI^-]), poly[1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium) bis(fluorosulfonyl)amide] (IC[TFSI^-]), poly{1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium) bis[(trifluoromethyl)sulfonyl]-amide} (IC[PF₆^-]), poly[1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium) bishexafluorophosphate] were synthesized with a simple ionic exchange method by using amphiphilic poly[1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium) bisbromide] (IC[Br^-]) as the intermediate ionic polymer. The chemical srutrcures of the target ICs were characterized by nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared spectroscopy (FTIR). It is shown that the target ICs could be spontaneously adsorbed on copper surface in N,N-dimethflormamide (DMF), and the tight adsorption films were formed on metal surface. The contacting angles suggest that the formed adsorption layers of target ICs on copper surface were characterized with hydrophobic nature. Furthermore, the target ICs-copper chemistry bonding was confirmed by various means. The electrochemistry analysis showed that the target ICs adsorption layers could prevent from copper corrosion in H₂SO₄solution efficiently, and the maximal anticorrosion efficiency was over 95% at 0.100 g/L. In particular, the target ICs showed 85% or above anticorrosion efficiency for copper at a low concentration of 0.025 g/L, which was greater than the intermediate polymer IC[Br^-]. In addition, an insight of mixed chemisorption and physisorption of the target ICs on metal surface was analyzed and discussed.

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