Dissipative Self-assembly Of Supramolecules Driven By Chemical Fuels

The structures and functions of even the simplest living organisms seemingly operate counter to the maximization of entropy and rely on the consumption of chemical energy to maintain dissipative states.These non-equilibrium supramolecular self-assembled structures require continuous energy input and dissipation,and once the energy is exhausted,the self-assembled structures spontaneously degrade and return to a thermodynamic equilibrium state;this fuel-driven transient self-assembly is referred to as dissipative self-assembly.A goal of modern science is to understand how simple chemical mixtures can transition from non-living components to truly living systems,as well as to produce new life-like materials and machines.Thus,inspired by chemical fuel-driven nonequilibrium self-assembly in nature,many synthetic supramolecular materials and networks in nonequilibrium have been built and exhibit special applications for temporal tunings,such as material adaptivity,transient catalysis,controlled directional motion,and oscillatory behavior,etc.However,compared to the huge number of chemical reactions,the artificial construction of nonequilibrium systems is remarkably infrequent,and to address the problems of nonequilibrium systems in current synthetic systems,such as the lack of functional applications,self-replicating functions in inanimate objects,repeated addition of high-energy fuels,and failure of nonequilibrium systems due to waste accumulation,this dissertation develops three dissipative self-assembly driven by chemical fuel,which are studied as follows.1.This dissertation developed a new transient polymer micelle system using 1-ethyl-3-（3-dimethylaminopropyl）carbodiimide（EDC）as the fuel and reactive esters as the energy dissipation unit.The EDC driven poly（ethylene glycol）-poly（acrylic acid）block copolymer reacts with small molecular hydroxyl compounds to prepare amphiphilic poly（ethylene glycol）-poly（acrylic acid）block polymer in water,which forms polymer micelles by self-assemble;afterward,polymer micelles disassemble due to hydrolysis of active esters.Chemically fueled EDC re-addition leads to re-emergence of dissipative self-assembly of polymeric micelle,and this cycle can be repeated ten times.In addition,the amount of EDC can regulate the lifetime of the transient micelles.2.Based on the EDC driven transient polymer micelle system,this dissertation found that transient micelles could capture various hydrophobic molecules from aqueous solutions during the self-assembly process and release these molecules in a controlled manner due to spontaneous degradation.Thus,the EDC driven transient polymer micelles are used as nanoreactors to accelerate chemical reactions in aqueous solutions,after dissipation is complete and catalytic products are released,it could improve the catalytic efficiency of the nanoreactors by adding EDC again to recapture reactants,solving the problem of product inhibition that exists in steady-state nanoreactors.3.Simulating self-replicating behavior in living organisms and exploiting the reversibility of esters,a chemical fuel-driven nonequilibrium autocatalytic micellar system based on surfactant formation is constructed.In this case,the surfactant is formed by the esterification reaction of two phase-separated reactants,hexanoic anhydride,and hydrophilic phenolic hydroxyl derivatives.The surfactant self-assembles to form micelles that catalyze the self-formation reaction to proceed.The negative feedback of the surfactant hydrolysis reaction is introduced by adding the more basic sodium carbonate in the system,which result in a state of thermodynamic disequilibrium of the surfactant and its assembly.Rather than replicating until the reactants are fully consumed,the metastable surfactant is depleted in the hydrolysis reaction after the fuel is exhausted,accompanied by the production of sodium hexanoate as a by-product,eventually reaching a state of system equilibrium.Afterward,the dissipative autocatalytic micellar system can be driven again by re-adding chemical fuel（caproic anhydride）,and the transient autocatalytic micellar system can be repeated at least three times.The generation and persistence of such chemical fuel-driven non-equilibrium autocatalytic micelles show how the coupled reaction cycle creates a metabolic network.4.To address the above problem of non-equilibrium state failure caused by waste accumulation in dissipative systems,and based on the reversible redox properties of methyl viologen derivatives,this dissertation developed a shake-induced transient color change system in a closed chemical system without waste accumulation.The system was constructed from dodecyl-modified violet essence(C₁₂-MV²⁺)in the presence of hydrazine hydrate.Initially,C₁₂-MV²⁺is reduced to the violet radical(C₁₂-MV^+·)and thus exhibits a purple color;upon shaking,C₁₂-MV^+·is rapidly oxidized back to C₁₂-MV²⁺by air,causing the system to move away from equilibrium and rendering the solution colorless.Once the solution remains stationary,C₁₂-MV²⁺gradually changes back to purple over time by the reduction of hydrazine hydrate to C₁₂-MV^+·,where nitrogen is released as a waste product.The shake-driven dissipative color change reaction can be repeated at least 10 times,and the transient color change cycle can be repeated at least 6times even in a closed system,and the re-introduction of air reactivates the non-equilibrium state color change cycle.Finally,ultrasound is introduced as a specific shaking method to generate template-free,time-modulated transient color change patterns.5.Based on a shake-driven dodecyl-modified methyl viologen dissipative color change system,this dissertation reports a shake-induced dissipative supramolecular polymerization in a closed chemical system without waste accumulation.The system was constructed from amphiphilic(C₁₂-MV²⁺)and 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt（PN）in the presence of hydrazine hydrate.Upon shaking,C₁₂-MV^+·is rapidly activated by air oxidation,causing the system to move away from equilibrium and subsequently C₁₂-MV²⁺and PN self-assemble into nanotubes through charge transfer interactions as well as amphiphilic interactions.Once the solution remains quiescent,the self-assembled nanotubes are spontaneously decomposed over time by the reducing agent,in which nitrogen is released as waste.Dissipative supramolecular polymerization can also be repeated at least 6 times.Mechanosensitive dissipative self-assembly process can be extended to the fabrication of transient supramolecular helices polymer by introducing chiral-charged small molecules into the system.More specifically,we show that shaking can induce transient fluorescence enhancement or burst,depending on the hydrophobicity of the violet extract(amphiphilic C₁₂-MV²⁺or hydrophilic methyl violet extract).Ultrasound was introduced as a specific shaking modality to generate template-free reproducible transient fluorescence patterning.