Sequence structure controllable polymerization-induced self-assembly

Polymerization-induced self-assembly(PISA)combines synthesis and self-assembly of artificial polymers in one-pot,which brings us one step closer to emulating biosynthesis.However,the reported PISA formulations primarily focus on developing nano-objects with new chemical compositions and rarely on structural regulation of polymers with specific components.Herein,sequence structure controllable polymerization-induced self-assembly(SCPISA)is reported by using 7-(2-methacryloyloxyethoxy)-4-methylcoumarin(CMA)as a monomer.During the copolymerization of 2-hydroxyethyl methacrylate(HEMA)and CMA,controlled incorporation of CMA units into the polymer chains can be realized by programmable light/heat changes.SCPISA-based P(HEMA-co-CMA)copolymers with the same composition but different sequence structures generate a range of assemblies.Moreover,the morphologies of the resultant nano-objects can also be controlled by regulating the feed molar ratio of CMA and HEMA,which is similar to the conventional PISA,but the synthesis procedure is obviously simplified in SCPISA.The versatility of the methodology is further demonstrated by the fabrication of different functional nano-objects with sequence structure-dependent morphologies in SCPISA systems with different functional monomers.

Self-assembly synthesis of solid polymer electrolyte with carbonate terminated poly (ethylene glycol) matrix and its application for solid state lithium battery

A facile one-pot synthesis of solid polymer electrolytes(SPEs), composed of carbonate terminated poly(ethylene glycol)(CH3O-PEG-IC), poly(ethylene glycol)-block-polystyrene(PEG-b-PS) block copolymer nanoparticles containing a conductive PEG corona, fumed SiO2 and Li TFSI salt via polymerization-induced self-assembly is proposed. This method to prepare SPEs has the advantages of one-pot convenient synthesis, avoiding use of organic solvent and conveniently adding inorganic additives. CH3O-PEG-IC combines advantages of PEG and polycarbonate, the in situ synthesized PEG-b-PS nanoparticles containing a rigid polystyrene(PS) core and a PEG corona guarantee continuous lithium ion transport in the synthesized SPEs, and the fumed SiO2 optimizes the interfacial properties and improves the electrochemical stability, all of which afford SPEs a well considerable room temperature ionic conductivity of 1.73 × 10^-4S/cm, high lithium transference number of 0.53, and wide electrochemical stability window of 5.5 V(vs. Li^+/Li). By employing these SPEs, the assembled solid state cells of Li FePO4 |SPEs|Li exhibit considerable cell performance.

Enzyme-assisted Photoinitiated Polymerization-induced Self-assembly in Continuous Flow Reactors with Oxygen Tolerance

Polymerization-induced self-assembly(PISA)is an emerging method for the preparation of block copolymer nano-objects at high concentrations.However,most PISA formulations have oxygen inhibition problems and inert atmospheres(e.g.argon,nitrogen)are usually required.Moreover,the large-scale preparation of block copolymer nano-objects at room temperature is challenging.Herein,we report an enzyme-assisted photoinitiated polymerization-induced self-assembly(photo-PISA)in continuous flow reactors with oxygen toleranee.The addition of glucose oxidase(GOx)and glucose into the reaction mixture can consume oxygen efficiently and constantly,allow the flow photo-PISA to be performed under open-air conditions.Polymerization kinetics indicated that only a small amount of GOx(0.5 μmol/L)was needed to achieve the oxygen tolerance.Block copolymer nano-objects with different morphologies can be prepared by varying reaction conditions including the degree of polymerization(DP)of core-forming block,monomer concentration,reaction temperature,and solvent composition.We expect this study will provide a facile platform for the large-scale production of block copolymer nano-objects with different morphologies at room temperature.

Polymerization-Induced Self-Assembly for the Preparation of Poly(N,N-dimethylacrylamide)-b-Poly(4-tert-butoxystyrene-co-pentafluorostyrene)Particles with Inverse Bicontinuous Phases

Main observation and conclusion Polymerization-induced self-assembly(PISA)is an effective method to prepare block copolymer(BCP)particles with various morphologies.However,BCPs with inverse bicontinuous phase structure have been rarely prepared via PISA.Herein,we report the preparation of particles.

Principles and Characteristics of Polymerization-Induced Self-Assembly with Various Polymerization Techniques

A chemical reaction that drives a physical polymer selfassembly process,namely,polymerization-induced self-assembly(PISA),combines block copolymer synthesis and nanoparticle formation efficiently at high polymer concentrations.Various nanoparticlemorphologies such as spheres,worms,and vesicles can be prepared readily in polar and nonpolarmedia.PISA has been well developed in combination with reversible addition-fragmentation chain transfer(RAFT)polymerization.Notably,developments with other polymerization methods are also achieved.In this report,first,we discuss the general principles of RAFT-PISA and the nanoparticles generated from this method.Specifically,new insights into polymer nucleation and subsequent morphological evolution are highlighted.Subsequently,PISA formulations that use other polymerization methods[atom transfer radical polymerization(ATRP),nitroxide-mediated polymerization(NMP),ring-opening metathesis polymerization(ROMP),and ring-opening polymerization(ROP)of N-carboxyanhydrides(NCAs)]are summarized in detail.Finally,more exotic PISA formulations are emphasized:these are based on organotelluriummediated living radical polymerization(TERP),living anionic polymerization(LAP),addition-fragmentation chain transfer(AFCT)polymerization,reversible complexation-mediated polymerization(RCMP),and cobalt-mediated radical polymerization(CMRP),or utilize a comonomer that undergoes radical ringopening polymerization(rROP).This reviewis concluded with a perspective on the status and potential of PISA.

Effect of Butyl α-Hydroxymethyl Acrylate Monomer Structure on the Morphology Produced via Aqueous Emulsion Polymerization-induced Self-assembly

Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl(n BHMA) and tert-butyl(t BHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of n BHMA and t BHMA employing poly(ethylene glycol) macromolecular chain transfer agents(macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for t BHMA, which has a higher water solubility than that of n BHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.

Preparation of pH-and reductive-responsive prodrug nanoparticles via polymerization-induced self-assembly

pH-and reductive-responsive prodrug nanoparticles are constructed via a highly efficient strategy, polymerization-induced selfassembly(PISA). First, reversible addition-fragmentation chain transfer(RAFT) polymerization of 2-(diisopropylamino) ethyl methacrylate(DIPEMA) and camptothecin prodrug monomer(CPTM) using biocompatible poly(N-(2-hydroxypropyl) methacrylamide)(PHPMA-CPDB) as the macro RAFT agent is carried out, forming prodrug diblock copolymer PHPMA-P(DIPEMA-co-CPTM). Then, simultaneous fulfillment of polymerization, self-assembly, and drug encapsulation are achieved via RAFT dispersion polymerization of benzyl methacrylate(Bz MA) using the PHPMA-P(DIPEMA-co-CPTM) as the macro RAFT agent. The prodrug nanoparticles have three layers, the biocompatible shell(PHPMA), the drug-conjugated middle layer(P(DIPEMA-co-CPTM)) and the PBz MA core, and relatively high concentration(250 mg/g). The prodrug nanoparticles can respond to two stimuli(reductive and acidic conditions). Due to reductive microenvironment of cytosol, the cleavage of the conjugated camptothecin(CPT) within the prodrug nanoparticles could be effectively triggered. p H-Induced hydrophobic/hydrophilic transition of the PDIPEMA chains results in faster diffusion of GSH into the CPTM units, thus accelerated release of CPT is observed in mild acidic and reductive conditions. Cell viability assays show that the prodrug nanoparticles exhibit well performance of intracellular drug delivery and good anticancer activity.

High-performance nano-splitters containing aggregation-induced emission luminogens for stereoselective crystallization obtained via polymerization-induced self-assembly

Collecting both enantiomorphs with high optical purity and yield in a single crystallization process can be achieved by adding aggregated polymeric“tailor-made”additives,known as nano-splitters.Inefficient preparation and large addition amount have hindered the practical application of such amazing nanoparticles.Herein,we report the first nano-splitters containing aggregation-induced emission luminogens prepared via polymerization-induced self-assembly of block copolymer,poly[(S)-2-(tert-butoxycarbonylamino)-6-(methacrylamido)hexanoic acid]-b-polystyrene,followed by the removal of tert-butoxycarbonyl groups.When added into the supersaturated solution of racemic amino acids(a.a.)with seeds,the fluorescent labeled nano-assemblies enantioselectivity dyed the crystals of S-a.a.and enabled the separation from colorless R-a.a.crystals in terms of fluorescent difference.Both enantiomers were obtained with high optical purity and yield(e.g.,R-asparagine monohydrate,>99 ee%;S-asparagine monohydrate,∼94 ee%;88%total yield).Owing to a low detection limit of fluorescence,the addition amount was reduced to 0.03 wt%without remarkably compromising the ee values of both enantiomorphs.Due to the low addition amount and efficient synthesis,the output–input ratio was increased greatly.

Synchronous Synthesis of Polymeric Vesicles with Controllable Size and Low-Polydispersity by Polymerization-Induced Self-Assembly

Comprehensive Summary The size and size distribution of polymeric nanoparticles have great impact on their physicochemical and biological properties.Polymerization-induced self-assembly(PISA)has been demonstrated to be an efficient method to fabricate various polymeric nanoparticles,among which polymeric vesicles have attracted great interest due to their unique hollow structure.

Reversible CO_(2)-, Photo-and Thermo-Triple Responsive Supramolecular Chirality of Azo-containing Block Copolymer Assemblies Prepared by Polymerization-induced Chiral Self-assembly

Polymerization-induced chiral self-assembly(PICSA)is an efficient strategy that not only allows the construction of the supramolecular chiral assemblies in a controlled manner but also can regulate the morphology in situ.Herein,a series of azobenzene-containing block copolymer(Azo-BCP)assemblies with tunable morphologies and supramolecular chirality were obtained through the PICSA strategy.The supramolecular chirality of Azo-BCP assemblies could be regulated by carbon dioxide(CO_(2))stimulus,and completely recovered by bubbling with Ar.A reversible morphology transformation and chiroptical switching process could also be achieved by the alternative 365 nm UV light irradiation and heatingcooling treatment.Moreover,the supramolecular chirality is thermo-responsive and a reversible chiral-achiral switching was successfully realized,which can be reversibly repeated for at least five times.This work provides a feasible strategy for constructing triple stimuli-responsive supramolecular chiral nano-objects in situ.

Synthesis of Self-assembled Star/Linear Block Copolymer Blends via Aqueous RAFT Dispersion Polymerization

Reversible addition-fragmentation chain transfer(RAFT)-mediated polymerization-induced self-assembly(PISA)of star block copolymer and linear block copolymer using a binary mixture of a star-like macro-RAFT agent and a linear macro-RAFT agent is reported.With this formulation,star block copolymer and diblock copolymer were formed simultaneously to generate colloidally stable star/linear block copolymer assemblies.Size exclusion chromatography(SEC)analysis confirmed the presence of two types of polymers in the final samples.The molar ratio of the star-like macro-RAFT agent and the linear macro-RAFT agent has a significant impact on the morphology of polymer assemblies.It was found that increasing the amount of star-like macro-RAFT agent facilitated the formation of higher-order morphologies.Additionally,effects of other reaction parameters including the length/number of the arm of the star-like macro-RAFT agent,degree of polymer(DP),monomer concentration on the morphology of star/linear block copolymer assemblies were also investigated.We expect that this work will offer new possibilities for the scalable preparation of polymer assemblies with unique structures and functions.

Polymersomes:From Macromolecular Self-Assembly to Particle Assembly

What is the most favorite and original chemistry developed in your research group?Ring-opening polymerization-induced self-assembly of N-carboxyanhydrides(NCA-PISA),and fusion-induced particle assembly(FIPA).How do you get into this specific field?Could you please share some experiences with our readers?NCA-PISA was developed to solve the biodegradability problem of nanoparticles by traditional PISA,while FIPA was inspired by nature.

Efficient Access to Inverse Bicontinuous Mesophases via Polymerization-Induced Cooperative Assembly

Polymerization-induced cooperative assembly(PICA)is reported to efficiently access inverse bicontinuous mesophases within particles consisting of amphiphilic block copolymers(BCPs)and solvophobic copolymers.Reversible addition-fragmentation chain transfer(RAFT)dispersion alternating copolymerization of styrene and pentafluorostyrene is conducted in 2%v/v toluene/ethanol by simultaneously using poly(N,N-dimethylacrylamide)(PDMA29)as a macromolecular chain transfer agent(macro-CTA)and small molecule CTA.

Mechanisms of Cup-Shaped Vesicle Formation Using Amphiphilic Diblock Copolymer

A cup shape is a dynamic morphology of cells and organelles. With the aim of elucidating the formation of the biotic cup-shaped morphology, this study investigated cup-shaped vesicles consisting of an amphiphilic diblock copolymer from the aspect of synthetic polymer chemistry. Cup-shaped vesicles were obtained by the polymerization-induced self-assembly of poly(methacrylic acid)-block-poly(n-butyl methacrylate-random-methacrylic acid), PMAA-b-P(BMA-r-MAA), in an aqueous methanol solution using the photo nitroxide-mediated controlled/living radical polymerization technique. Field emission scanning electron microscopic observations demonstrated that the cup-shaped vesicles were suddenly formed during the late stage of the polymerization due to the extension of the hydrophobic P(BMA-r-MAA) block chain. During the early stage, the polymerization produced spherical vesicles rather than a cup shape. As the hydrophobic block chain was extended by the polymerization progress, the spherical vesicles reduced the size and were accompanied by the generation of small particles that were attached to the vesicles. The vesicles continued to reduce the size due to further extension of the hydrophobic chain;however, they suddenly grew into cup-shaped vesicles. This growth was accounted for by a change in the critical packing shape of the copolymer due to the hydrophobic chain extension. These findings are helpful for a better understanding of the biotic cup-shaped vesicle formation.

Effect of Solvophilic Chain Length in PISA Particles on Pickering Emulsion

The morphology of polymeric nanoparticles prepared by polymerization-induced self-assembly(PISA)is depended on the degree of polymerization of the solvophilic and solvophobic blocks.Herein,a series of poly(N,N-dimethylaminoethyl methacrylate)-b-poly(benzyl methacrylate)(PDMA-b-PBzMA)diblock copolymer spherical nanoparticles were synthesized via reversible addition-frag-mentation chain transfer(RAFT)mediated PISA.These diblock copolymer nanoparticles are with nearly the same hydrodynamic size and solvophobic chain length,but with different solvophilic chain length.We used these nanoparticles to stabilize the oil-in-water Pickering emulsion.We find that the stability of Pickering emulsion increases with the length of solvophilic chain of the nanoparticles.Moreover,the droplet size of the Pickering emulsion can be tailored by varying the oil/water ratio and concentration of nanoparticles.

In Situ Synthesis of Branched Block Copolymer Assemblies via RAFT Dispersion Polymerization Using Branched Macro-RAFT Agents

Here,we demonstrate the use of branched macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agents in RAFT dispersion polymerization,to access branched block copolymers as well as well-defined branched block copolymer assemblies.Two types of branched macro-RAFT agents were first synthesized by using either a monofunctional chain transfer monomer or a difunctional chain transfer monomer in RAFT polymerization,and subsequently utilized in RAFT dispersion polymerization.It was found that only branched macro-RAFT agents synthesized from the difunctional chain transfer monomer could lead to colloidally stable assemblies with well-defined morphologies.Reaction conditions including monomer concentration,degree of polymerization (DP) of the core-forming block,and DP of the solvophilic segment on morphologies of branched block copolymer assemblies were investigated in detail.Size exclusion chromatography (SEC) analysis further confirmed the successful formation of branched block copolymers by using branched macro-RAFT agents.This work on the synthesis of branched block copolymer assemblies by RAFT dispersion polymerization offers new opportunities for the rational design of polymer assemblies with well-defined structures.

Template-Directed Fabrication of Anatase TiO2 Hollow Nanoparticles and Their Application in Photocatalytic Degradation of Methyl Orange

Polymerization-induced self-assembly （PISA） was used to fabricate polymeric nanoparticles via reversible ad- dition-fragmentation chain transfer （RAFT） dispersion polymerization of benzyl methacrylate （BzMA） using di- block copolymer poly（glycerol monomethacrytate）-block-poly（2-dimethylaminoetbyl methacrylate） （PGMMA- PDMAEMA-CTA） as the macro RAFT agent. The dispersion of polymeric nanoparticles with a final concentration of about 210 mg/g （solid content of 21%） was obtained via this efficient method （PISA）. The resultant polymeric nanoparticles consisting of corona-shell-core three layers with weak polyelectrolyte PDMAEMA as the shell were used as sacrificial template to fabricate TiO2 hollow nanoparticles. The negatively charged titanium precursor was absorbed into the PDMAEMA shell via the electrostatic interaction, and hydrolyzed to form polymer/TiO2 hybrid nanoparticles. Anatase TiO2 hollow nanoparticles were formed after removing the polymeric templates by calcina- tion at 550 ℃. The experiments of photocatalytic degradation of methyl orange showed that the resultant anatase TiO2 hollow nanoparticles had high photocatalytic activity and good reusability.