Supramolecular polymer-based gel fracturing fluid with a double network applied in ultra-deep hydraulic fracturing

A gel based on polyacrylamide,exhibiting delayed crosslinking characteristics,emerges as the preferred solution for mitigating degradation under conditions of high temperature and extended shear in ultralong wellbores.High viscosity/viscoelasticity of the fracturing fluid was required to maintain excellent proppant suspension properties before gelling.Taking into account both the cost and the potential damage to reservoirs,polymers with lower concentrations and molecular weights are generally preferred.In this work,the supramolecular action was integrated into the polymer,resulting in significant increases in the viscosity and viscoelasticity of the synthesized supramolecular polymer system.The double network gel,which is formed by the combination of the supramolecular polymer system and a small quantity of Zr-crosslinker,effectively resists temperature while minimizing permeability damage to the reservoir.The results indicate that the supramolecular polymer system with a molecular weight of(268—380)×10^(4)g/mol can achieve the same viscosity and viscoelasticity at 0.4 wt%due to the supramolecular interaction between polymers,compared to the 0.6 wt%traditional polymer(hydrolyzed polyacrylamide,molecular weight of 1078×10^(4)g/mol).The supramolecular polymer system possessed excellent proppant suspension properties with a 0.55 cm/min sedimentation rate at 0.4 wt%,whereas the0.6 wt%traditional polymer had a rate of 0.57 cm/min.In comparison to the traditional gel with a Zrcrosslinker concentration of 0.6 wt%and an elastic modulus of 7.77 Pa,the double network gel with a higher elastic modulus(9.00 Pa)could be formed only at 0.1 wt%Zr-crosslinker,which greatly reduced the amount of residue of the fluid after gel-breaking.The viscosity of the double network gel was66 m Pa s after 2 h shearing,whereas the traditional gel only reached 27 m Pa s.

A New Three-dimensional Supramolecular Polymer Built from Non-covalent Bonding Interactions

A new complex, [Ni2（L）4（H2O）8]（1, L1 = 4-（1H-imidazol-4-yl）benzoic acid）, has been hydrothermally prepared and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis and PXRD. Complex 1 crystallizes in monoclinic, space group P21/c with α = 22.281（2）, b = 7.3959（7）, c = 24.978（3） ？, β = 90.876（10）, V = 4115.6（7） ？3, Z = 8, C20H22N4O8Ni, Mr = 505.13, Dc = 1.630 g/cm3, μ = 1.001 mm-1, S = 1.080, F（000） = 2096, the final R = 0.452 and wR = 0.1152 for 9380 observed reflections （I 〉 2σ（I））. The result of X-ray diffraction analysis revealed three different kinds of Ni（II） centre mononuclear molecules in the asymmetric unit. The independent mononuclear units are bridged to form a three-dimensional supramolecular polymer by extensive hydrogen bonds and C–H… non-covalent bonding interactions.

Synthesis, Crystal Structure and Property of a Series of Supramolecular Polymers Based on Novel 3,5-Dimethyl- 2,6-bis(3-(pyrid-2-yl)-1,2,4-triazolyl)pyridine Ligand

Solvothermal reactions of 3,5-dimethyl-2,6-bis（3-（pyrid-2-yl）-1,2,4-triazolyl） pyridine （L）, 1,4-benzendicarboxylic acid （H2bdc）, and transitional metal cations of M11 （M = Mn, Co, Cd） in the presence of oxalic acid （H2ox） afford three novel supramolecular polymers （CPs）, namely, {[M2（ox）（L）2][bdc][M2（Hox）2（OH）（H2O）4]·3H2O}n （M = Mn for 1, Co for 2, Cd for 3）. Single-crystal X-ray diffraction analysis reveals that complexes 1-3 are isostructural and the 3D supramolecular structure was connected through non-covalent interactions. With the help of H2ox, the L ligands cheated with center atoms forming a butterfly [M2（ox）（L）2]2＋ building block. The bdc2- ligand linked with the unprecedented [M2（Hox）2（OH）2（H2O）4] units through strong O-H...O hydrogen bonds forming a zigzag chain, which are further connected through π-π interactions between L and bdc2- ligands to form a 3D supramolecular structure. Moreover, elemental analyses, IR, thermogravimetric, PXRD and luminescence have been investigated.

Supramolecular Polymer Intertwined Free-Standing Bifunctional Membrane Catalysts for All-Temperature Flexible Zn-Air Batteries

Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.

Two Three-dimensional Supramolecular Polymer Built from Mixed N-Donor and Carboxylate Ligands

Two new complexes, [Mn（L）（mmbda）（H_2O）]（1） and [Co（L）（btc）（H_2O）]·H_2O（2）, were synthesized by reacting the corresponding metal（Ⅱ） salts with rigid ligand 1,4-di（1Himidazol-4-yl）benzene（L） and two different carboxylic acids of 5-methylisophthalic acid（H_2mmbda） and 1,2,4-benzenetricarboxylic acid（H_3btc）, respectively. The structures of the complexes were characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis and PXRD. Complex 1 crystallizes in triclinic, space group P1 with a = 6.9436（4）, b = 9.7306（6）, c = 15.5302（10） ？, α = 73.7430（10）, β = 85.1010（10）, γ = 70.0360（10）o, V = 946.75（10） ？~3, Z = 2, C_（21）H_（20）N_4O_5 Mn, M_r = 463.33, D_c = 1.618 g/cm^3, μ = 0.742-1, S = 1.002, F（000） = 474, the final R = 0.0285 and wR = 0.0600 for 4328 observed reflections（I 〉 2σ（I））. Complex 2 crystallizes in monoclinic, space group P2_1/n with a = 12.5216（12）, b = 7.3312（8）, c = 22.510（2） ？, β = 93.104（2）o, V = 2063.3（4） ？~3, Z = 4, C_（21）H_（18）N_4O_8Co, M_r = 513.31, D_c = 1.646 g/cm^3, μ = 0.892^（-1） mm, S = 1.096, F（000） = 1044, the final R = 0.0673 and wR = 0.1780 for 3594 observed reflections（I 〉 2σ（I））. Both of complexes are one-dimensional（1D） chain structures and rich hydrogen bonds extend such 1D chains to form three-dimensional（3D） supramolecular polymers.

AIE interfacial supramolecular polymers

High monomer concentration is a requisite for engendering the aggregation-induced emssion(AIE)phenomenon as well as the formation of supramolecular polymers.Therefore,this is supposed to ensure the generation of AIE supramolecular polymers,wherein the monomer soluability takes effect.Nevertheless,parts of supramolecular monomers are considered as poessessing different soluability towards the same sovlent,through which the polymerzation process is thus hard to proceed.Interfacial polymerzation gets over the soluabilty restriction,providing a facile method for propelling the reaction of thesemonomers.Herein,we had prepared M1 containing tetraphenylethene(TPE)functionalized with two terpyridine derivatives,then making M1 dissolving in CHCl3 to give solutions.Cu^(2+)solutions were fabricated through dissolving CuCl_(2)into H2O.Towards mixing those solutions,AIE interfacial supramolecular polymers(AIEISPs)displaying green fluorescence were generated at the interface of two phases on the basis of metal-coordination between terpyridine and Cu^(2+).These AIEISPs were certificated to possess the stimuli-responsiveness,for which the excessive addition of tetrabutylammonium hydroxide would cause the structure destruction owing to the stronger bonding ability with Cu^(2+)than that of terpyridine.These fabricated AIEISPs had provided a new avenue to prepare AIE supramolecular polymers.

Artificial stepwise light harvesting system in water constructed by quadruple hydrogen bonding supramolecular polymeric nanoparticles

Stepwise energy transfer is ubiquitous in natural photosynthesis,which greatly promotes the widespread use of solar energy.Herein,we constructed a supramolecular light harvesting system based on sequential energy transfer through the hierarchical self-assembly of M,which contains a cyanostilbene core flanked by two ureidopyrimidinone motifs,endowing itself with both aggregation-induced emission behavior and quadruple hydrogen bonding ability.The monomer M can self-assemble into hydrogen bonded polymers and then form supramolecular polymeric nanoparticles in water through a mini-emulsion process.The nanoparticles were further utilized to encapsulate the relay acceptor ESY and the final acceptor NDI to form a two-step FRET system.Tunable fluorescence including a white-light emission was successfully achieved.Our work not only shows a desirable way for the fabrication of efficient two-step light harvesting systems,but also shows great potential in tunable photoluminescent nanomaterials.

The New Methods for Characterization of Molecular Weight of Supramolecular Polymers

Supramolecular polymers,as a type of dynamic polymers,are subordinate to the interdisciplinary field of polymer chemistry and supramolecular chemistry,whose development has greatly promoted the prosperity of new materials.Notably,molecular weight is one of the most important parameters of supramolecular polymers,which affects the physical/chemical properties and processing applications of materials.Developing new methods for characterizing the molecular weight of supramolecular polymers is crucial for advancing the development of supramolecular polymers.In this review,we elaborate and summarize three strategies for characterizing the molecular weight of supramolecular polymers that recently reported by our research group according to the characteristics of supramolecular polymers,including(1)the molecular weight distinction corresponding to variable fluorescence colors,(2)matching different molecular weights with different fluorescence lifetime,(3)transforming supramolecular polymers into mechanically interlocked polymers or covalent polymers.Besides,we also discuss the limitations of current methods for characterizing supramolecular polymers.We hope that this review can promote the development of supramolecular polymers and significantly inspire to exploit new methods to characterizing molecular weight of supramolecular polymers.

Bolstering the Mechanical Robustness of Supramolecular Polymer Network by Mechanical Bond

Supramolecular polymer networks(SPNs)are celebrated for their dynamic nature,yet they often exhibit inadequate mechanical properties.Thus far,the quest to bolster the mechanical resilience of SPNs while preserving their dynamic character presents a formidable challenge.Herein,we introduce[2]rotaxane into SPN to serve as another cross-link,which could effectively enhance the mechanical robustness of the polymer network without losing the dynamic properties.Compared with SPN,the dually cross-linked network(DPN)demonstrates superior breaking strength,Young’s modulus,puncture force and toughness,underscoring its superior robustness.Furthermore,the cyclic tensile tests reveal that the energy dissipation capacity of DPN rivals,and in some cases surpasses,that of SPN,owing to the efficient energy dissipation pathway facilitated by[2]rotaxane.In addition,benefiting from stable topological structure of[2]rotaxane,DPN exhibits accelerated recovery from deformation,indicating superior elasticity compared to SPN.This strategy elevates the performance of SPNs across multiple metrics,presenting a promising avenue for the development of high-performance dynamic materials.

Pillar[5]arene based artificial light-harvesting supramolecular polymer for efficient and recyclable photocatalytic applications

Photosynthesis is the process through which living plants utilize photosynthetic pigments,such as chlorophyll,to convert CO_(2)and water into organic compounds and release O_(2)under visible light.In this study,we have successfully constructed a fluorescent supramolecular polymer(P5Py_(2)/Zn/Gen)n by employing orthogonal pillar[5]arene-based molecular recognition and metal ion coordination.Within the supramolecular polymer,the guest molecule Gen unit acts as a light-harvesting moiety,as the ACQ effect is inhibited by host-guest interactions,while the(Py)_(2)/Zn center serves as a catalytic site.By employing this orthogonal self-assembly strategy,we have enhanced the stability of both the donor and acceptor in catalyzing the reduction of p-nitrophenol to p-aminophenol.Moreover,this photocatalyst can be reused at least 5 times without significant conversion loss.These findings provide a pathway for constructing a recyclable artificial LHS that mimics the entire photosynthesis process.

Supramolecular Polymerization of Hydrogen-Bonded Trimers in Bulk and Aqueous Medium

Synthetic molecules that form functional noncovalent assemblies in water have received much attention for their potential applications as biomaterials.In this work,we introduce a novel water-compatible monomer based on the phthalhydrazide moiety that assembles into hydrogen-bonded trimeric discs.In bulk,the material exhibits a cylindrical nanostructure in the liquid-crystalline phase at elevated temperatures,morphologically distinct from the crystalline lamellar phase.In water,these molecules effectively form cylinders in a one-dimensional fashion,yielding fibrous structures.The formation of these supramolecular polymers follows a cooperative mechanism,as evidenced by denaturation studies.The trimerized pattern represents a new category of aqueous su pramolecular polymers with future prospects for functional complex molecular systems.

A Fluorinated,Ion-Conducting and Adaptive Supramolecular Polymer Protective Layer for Stabilizing Lithium Metal Anodes

Perfluoropolyether(PFPE)is a promising material for protective coatings on Li metal anodes due to its chemical inertness and minimal swelling in electrolytes.However,a conventional PFPE coating with poor ionic conductivity and mechanical stability is still not satisfactory for long-term cycling of Li anodes.Here,we design and synthesize an adaptive and high-conductivity supramolecular polymer(PFPE-EG-I).This polymer is constructed from PFPE chains,ethylene glycol(EG)segments,and hydrogen-bonding moieties derived from isophoronediisocyanate,serving as a multifaceted artificial solid electrolyte interphase(SEI).The incorporated EG segments enhance the Li+conductivity of the SEI,and the hydrogen-bonding units introduce a dynamic self-adaptive behavior to the polymer matrix.A solution-processed PFPE-EG-I coating is demonstrated to promote uniform Li deposition and mitigate side reactions between Li and the electrolyte.Consequently,this leads to enhanced coulombic efficiency and prolonged cycle longevity in lithium metal batteries(LMBs).The innovative design of this multifunctional artificial SEI offers a promising avenue for the realization of dendrite-free Li anodes,paving the way for the advancement of high-performance LMBs.

Hydrogen-Bonding Crosslinked Supramolecular Polymer Materials:From Design Evolution of Side-Chain Hydrogen-Bonding to Applications

Hydrogen bonds(H-bonds)are the most essential non-covalent interactions in nature,playing a crucial role in stabilizing the secondary structures of proteins.Taking inspiration from nature,researchers have developed several multiple H-bonds crosslinked supramolecular polymer materials through the incorporation of H-bond side-chain units into the polymer chains.N-acryloyl glycinamide(NAGA)is a monomer with dual amides in the side group,which facilitates the formation of multiple dense intermolecular H-bonds within poly(N-acryloyl glycinamide)(PNAGA),thereby exhibiting diverse properties dependent on concentration and meeting various requirements across different applications.Moreover,numerous attempts have been undertaken to synthesize diverse NAGA-derived units through meticulous chemical structure regulation and fabricate corresponding H-bonding crosslinked supramolecular polymer materials.Despite this,the systematic clarification of the impact of chemical structures of side moieties on intermolecular associations and material performances remains lacking.The present review will focus on the design principle for synthesizing NAGA-derived H-bond side-chain units and provide an overview of the recent advancements in multiple H-bonds crosslinked PNAGA-derived supramolecular polymer materials,which can be categorized into three groups based on the chemical structure of H-bonds units:(1)monomers with solely cooperative H-bonds;(2)monomers with synergistic H-bonds and other physical interactions;and(3)diol chain extenders with cooperative H-bonds.The significance of subtle structural variations in these NAGA-derived units,enabling the fabrication of hydrogen-bonded supramolecular polymer materials with significantly diverse performances,will be emphasized.Moreover,the extensive applications of multiple H-bonds crosslinked supramolecular polymer materials will be elucidated.

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

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.

Cooperative Supramolecular Polymerization of Propeller-Shaped Triphenylamine Cyanostilbenes for Explosive Detection

Self-assembly ofπ-conjugated compounds into supramolecular polymers has received considerable attention because of their intrinsic scientific interests and technological applications.As compared toπ-conjugated rods,discotics,and macrocycles,propeller-shapedπ-conjugated molecules have been less exploited to form long-range-ordered supramolecular polymers.Herein a novel type of supramolecular polymers has been constructed on the basis of propeller-shaped triphenylamine cyanostilbenes.The designed compound adopts nucleation-elongation cooperative mechanism for the supramolecular polymerization process,because of the participation of three-fold hydrogen bonds between the neighbouring monomers.The supramolecular polymeric state displays amplified chirality and enhanced emission than those in the monomeric state.The resulting supramolecular polymers exhibit severe emission quenching upon addition of 2,6-dinitrotoluene,ascribed to photoinduced electron transfer from the triphenylamine cyanostilbenes to the explosive analyte.The current study proves the feasibility to supramolecular polymerize propeller-likeπ-conjugated molecules,serving as a promising type of explosive sensor owing to their guest encapsulation and signal amplification capabilities.

Supramolecular Polymerization of DNA Double-Crossover-Like Motifs in Various Dimensions

Double-crossover-like(DXL)molecules are a series of DNA motifs containing two strands with identical or different sequences.These homo-or hetero-dimers can further polymerize into bulk structures through specific hydrogen bonding between sticky ends.DXL molecules have high designability,predictivity and sequence robustness;and their supramolecular polymerization products would easily achieve controllable morphology.In addition,among all available DNA nanomotifs,DXL molecules are small in size so that the cost of DXL-based nanostructures is low.These properties together make DXL-based nanostructures good candidates for patterning,templating,information and matter storage,etc.Herein,we will discuss DXL motifs in terms of the detailed molecular design,and their supramolecular polymerization in various dimensions,and related applications.

Cation-π and electrostatic interactions co-driven assembly of two-dimensional heteropore supramolecular polymers with rapid iodine capture capability

Constructing two-dimensional(2D)supramolecular polymers with complicated hierarchical porosity significantly contributes to developing effective strategies to control delicate self-assembly architectures,thus facilitating the fabrication of advanced 2D organic functional materials.Here,we report utilizing cooperative cation-πand electrostatic interactions to construct a series of robust 2D heteropore supramolecular polymers(2D HPSPs)with hierarchical pore structures,in which hexagonal and rectangular pores are alternately and periodically arranged,and the pore sizes can be finely tuned.Remarkably,the as-prepared 2D HPSPs exhibit excellent iodine(I_(2))capture rate(a maximum K80%value is 2.25 g h^(-1)),and present a novel mechanism involving transport-adsorption spatiotemporal separation for rapid I_(2)capture.In this mechanism,the transport of free I_(2)is first conducted in large hexagonal pores,and then I_(2)can be preferentially adsorbed in small rectangular pores,thereby preventing the transfer channels from blocking and greatly improving the adsorption kinetics.

Synthesis of stimuli-responsive pillararene-based supramolecular polymer materials for the detection and separation of metal ions

A stimuli-responsive supramolecular polymer network(G-(CN)_(2)⊂BXDSP5)with aggregation-induced emission(AIE)properties has been efficiently constructed by host-guest interactions between pillar[5]arene derivative BXDSP5 and a homoditopic guest G-(CN)_(2),which shows not only excellent fluorescence properties due to the AIE effect but also desirable ion-sensing abilities in both solution and solid states,holding great potential in the applicable fluorescence detection for Fe^(3+).The resultant G-(CN)_(2)⊂BXDSP5 can be transformed into supramolecular polymer gel at high concentration via multiple noncovalent interactions,showing multi-stimuli-responsiveness in response to temperature change,mechanical force,and competitive agent.Meanwhile,the xerogel of supramolecular polymer material has been successfully used to remove Fe^(3+)from water with high adsorption efficiency.In addition,an ionresponsive film based on supramolecular polymer has also been developed,which can serve as a practical and convenient fluorescence test kit for detecting Fe^(3+).

In Situ Supramolecular Polymerization via Organometallic-Catalyzed Macromolecular Metamorphosis

Integrating catalytic reactions with molecular assembly is a promising means of achieving controllable supramolecular polymerization.We report herein a novel and controllable method for in situ supramolecular polymerization via organometallic-catalyzed macromolecular metamorphosis.To this end,covalent polymers with polypentenamer backbones and pendant supramolecular motifs are designed and synthesized.By depolymerizing the polymers with Grubbs catalysts,the supramolecular motifs can be gradually released from the polymers to the solution.Supramolecular polymerization occurs when a critical concentration is reached.The supramolecular polymerization process was readily controlled by varying the rate of the depolymerization reaction.This work presents a novel approach that uses organometallic catalysis to transform covalent polymers into supramolecular polymers.It offers a new means of constructing complex molecular systems in a controllable manner.

Supramolecular Polymerization Driven by the Dimerization of Single-stranded Helix to Double-stranded Helix

We reported a type of strong and highly directional non-covalent interactions based on the dimerization of single-stranded helix to double-stranded helix that can achieve supramolecular polymerization, giving rise to the formation of linear supramolecular polymers.