Amphiphilic Block Copolymers Research Articles

Bottlebrush Block Copolymers at the Interface of Immiscible Liquids: Adsorption and Lateral Packing.

Amphiphilic bottlebrush block copolymers (BBCPs), having a hydrophilic bottlebrush polymer (BP) linked covalently to a hydrophobic BP, were found to segregate to liquid-liquid interfaces to minimize the free energy of the system. The key parameter influencing the outcome of the experiments is the ratio between the degree of polymerization of the backbone (NBB) and that of the side-chain brushes (NSC). Specifically, a spherical, star-like configuration results when NBB < NSC, while a cylindrical, bottlebrush-like shape is preferred when NBB > NSC. Dynamic interfacial tension (γ) and fluorescence recovery after photobleaching (FRAP) measurements show that the BBCP configuration influences the areal density and in-plane diffusion at the fluid interface. The characteristic relaxation times associated with BBCP adsorption (τA) and reorganization (τR) were determined by fitting time-dependent interfacial tension measurements to a sum of two exponential relaxation functions. Both τA and τR initially increased with NBB up to 92 repeat units, due to the larger hydrodynamic radius in solution and slower in-plane diffusivity, attributed to a shorter cross-sectional diameter of the side-chains near the block junction. This trend reversed at NBB = 190, with shorter τA and τR attributed to increased segregation strength and exposure of the bare water/toluene interface due to tilting and/or wiggling of the backbone chains, respectively. The adsorption energy barrier decreased with higher NBB, due to a reduced BBCP packing density at the fluid interface. This study provides fundamental insights into macromolecular assembly at fluid interfaces, as it pertains to unique bottlebrush block architectures.

Peculiar Behaviour of Methyl Methacrylate (MMA) Emulsion Polymerization-induced Self-assembly (PISA) Mediated by RAFT Using Poly(methacrylic acid) (PMAA) Macromolecular Chain Transfer Agent.

Reversible addition-fragmentation chain transfer (RAFT) emulsion polymerization of methyl methacrylate (MMA) is successfully performed in water in the presence of a poly(methacrylic acid) (PMAA) macromolecular chain transfer agent (macroCTA) leading to the formation of self-stabilized PMAA-b-PMMA amphiphilic block copolymer particles. At pH = 3.7, the reactions are well-controlled with narrow molar mass distributions. Increasing the initial pH, particularly above 5.6, results in a partial loss of reactivity of the PMAA macroCTA. The effect of the degree of polymerization (DPn) of the PMMA block, the solids content, the nature of the hydrophobic segment and the pH on the morphology of the obtained diblock copolymer particles is then investigated. Worm-like micelles are formed for a DPn of PMMA of 20 (PMMA20), while "onion-like" particles and spherical vesicles are obtained for PMMA30 and PMMA50, respectively. In contrast, spherical particles are obtained for the DPns higher than 150. This unusual evolution of particle morphologies upon increasing the DPn of the PMMA block seems to be related to hydrogen bonds between hydrophilic MAA and hydrophobic MMA units. This article is protected by copyright. All rights reserved.

Dual lanthanide Complexes-Loaded ratiometric nanothermometer for elucidating intracellular variations of temperature and calcium transport

Herein, we report a ratiometric nanothermometer to study the correlation of heat/temperature and intracellular calcium transport. Firstly, poly(methyl methacrylate)-based copolymeric nanoparticles (NPs) from nanoprecipitation encapsulates two lanthanide complexes (Eu(DNPD)3Phen and Sm(DBM)3Phen) to enhance fluorescence of lanthanide ions (Ln3+). NPs were thereafter coated with an amphiphilic block copolymer pluronic F-127 to prevent nonspecific interaction between NPs and proteins, which ensures internalization of the nanothermometer into living cells. The back energy transfer (BET) from the excited state of Ln3+ to the triplet energy levels of ligand endows the temperature dependence on ratiometric fluorescence of Eu3+ and Sm3+. This nanothermometer has excellent anti-interference ability, ensuring accurate cell temperature measurement within a range of 29.0–40.0℃. It exhibits a maximum relative thermal sensitivity of 1.9 % ℃-1 at 29.0℃ and a minimum temperature resolution of 0.1℃ at 39.0℃ in live HeLa cells. The nanothermometer was applied for studying temperature or heat induced intracellular Ca2+ transport. It illustrated that free cytoplasmic Ca2+ concentration ([Ca2+]i) increased only when the cell temperature reached a certain threshold under photothermal stimulation, and the rise of temperature corresponds to the increase of [Ca2+]i. Furthermore, Ca2+ burst induced Ca2+ transport from cytoplasm to endoplasmic reticulum, which promoted ATP hydrolysis along with the rise of intracellular temperature. 200 s stimulation with FCCP enhanced ca. 1.7℃ of intracellular temperature along with 2.2 folds increment of [Ca2+]i, as FCCP induces Ca2+ efflux from mitochondria by increasing proton concentration therein. These results indicate that a close relationship between intracellular temperature and Ca2+ transport, which is of great significance for further understanding the role of temperature in signaling pathways and neurotransmitter release events.

Ultrasmall Inorganic Mesoporous Nanoparticles: Preparation, Functionalization and Application.

Ultrasmall mesoporous nanoparticles (< 50nm), a unique porous nanomaterial, have been widely studied in the last decade owing to the abundant advantages, involving rich mesopores, low density, high surface area, numerous reaction sites, large cavity space, ultrasmall size, etc. It has been widely used in a range of applications, involving absorption, catalysis, energy storage, fluorescence imaging, and drug delivery/therapy. This paper presents a review of recent advances in the preparation, functionalization and applications of ultrasmall inorganic mesoporous nanoparticles for the first time. The soft monomicelles-directed method, in contrast to the hard-template and template-free methods, is more flexible in the synthesis of mesoporous nanoparticles. This is because the amphiphilic micelle has tunable functional blocks, controlled molecule masses, and adjusted configurations and mesostructures. Focus on the soft micelle directing method, monomicelles could be classified into four types, i.e., the Pluronic-type block copolymer monomicelles, laboratory-synthesized amphiphilic block copolymers monomicelles, the single-molecule star-shaped block copolymer monomicelles, and the small-molecule anionic/cationic surfactant monomicelles. This paper also reviews the functionalization of the inner mesopores and the outer surfaces, which includes constructing the yolk-shell structures (encapsulated nanoparticles), anchoring the active components packed on the shell and building an asymmetric Janus architecture. Then, several representative applications, involving catalysis, energy storage, and biomedicines are presented. Finally, the prospects and challenges of controlled synthesis and large-scale applications of ultrasmall mesoporous nanoparticles in the future are foreseen. This article is protected by copyright. All rights reserved.

Synthesis of PEGylated amphiphilic block copolymers with pendant linoleic moieties by combining ring-opening polymerization and click chemistry.

This study focused on synthesizing and characterizing PEGylated amphiphilic block copolymers with pendant linoleic acid (Lin) moieties as an alternative to enhance their potential in drug delivery applications. The synthesis involved a two-step process, starting with ring-opening polymerization of ε-caprolactone (CL) and propargylated cyclic carbonate (MCP) to obtain PEG-b-P(CL-co-MCP) copolymers, which were subsequently modified via click chemistry. Various reaction conditions were explored to improve the yield and efficiency of the click chemistry step. The use of anisole as a solvent, N-(3-azidopropyl)linoleamide as a substrate, and a reaction temperature of 60°C proved to be highly efficient, achieving nearly 100% conversion at a low catalyst concentration. The resulting copolymers exhibited controlled molecular weights and low polydispersity, confirming the successful synthesis. Furthermore, click chemistry allows for the attachment of Lin moieties to the copolymer, enhancing its hydrophobic character, as deduced from their significantly lower critical micelle concentration than that of traditional PEG-b-PCL systems, which is indicative of enhanced stability against dilution. The modified copolymers exhibited improved thermal stability, making them suitable for applications that require high processing temperatures. Dynamic light scattering and transmission electron microscopy confirmed the formation of micellar structures with sizes below 100 nm and minimal aggregate formation. Additionally, 1H NMR spectroscopy in deuterated water revealed the presence of core-shell micelles, which provided higher kinetic stability against dilution.

Regulating the chiroptical expression of aggregated solvophobic core by solvophilic segments.

The investigation of chiral supramolecular stacking is of essential significance for the understanding of the origin of homochirality in nature. Unlike structurally well-defined amphiphilic liposomes, it remains unclear whether the solvophilic segments of the amphiphilic block copolymer play a decisive role in the construction of asymmetric superstructures. Herein, we present insights into the stacking patterns and morphological regulation in azobenzene-containing block copolymer assemblies solely by modulating the solvophilic chain length. The solvophilic poly(methacrylic acid) (PMAA) segments of different molecular weights could cause multi-mode chirality inversions involving stacking transitions between intra-chain π-π stacking, inter-chain H-aggregation and J-aggregation. Furthermore, the length of the solvophilic PMAA also affects the morphology of the chiral supramolecular assemblies; rice grain-like micelles, worms, nanofibers, floccules and lamellae could be prepared at different solvophilic-solvophobic balance. The comprehensive mechanism was collectively revealed by utilizing various measurement methods, such as including circular dichroism (CD), small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). This study highlights the critical importance of fully dissolved solvophilic segments for the chiroptical regulation of the aggregated core, providing new insights into the arrangement of chiral supramolecular structures in polymer systems. This article is protected by copyright. All rights reserved.

A Versatile Synthesis Platform Based on Polymer Cubosomes for a Library of Highly Ordered Nanoporous Metal Oxides Particles.

Polymer cubosomes (PCs) have well-defined inverse bicontinuous cubic mesophases formed by amphiphilic block copolymer bilayers. The open hydrophilic channels, large periods, and robust physical properties of PCs are advantageous to many host-guest interactions and yet not fully exploited, especially in the fields of functional nanomaterials. Here, the self-assembly of poly(ethylene oxide)-block-polystyrene block copolymers is systematically investigated and a series of robust PCs is developed via a cosolvent method. Ordered nanoporous metal oxide particles are obtained by selectively filling the hydrophilic channels of PCs via an impregnation strategy, followed by a two-step thermal treatment. Based on this versatile PC platform, the general synthesis of a library of ordered porous particles with different pore structures , tunable large pore size (18-78nm), high specific surface areas (up to 123.3m2g-1 for WO3) and diverse framework compositions, such as transition and non-transition metal oxides, rare earth chloride oxides, perovskite, pyrochlore, and high-entropy metal oxides is demonstrated. As typical materials obtained via this method, ordered porous WO3 particles have the advantages of open continuous structure and semiconducting properties, thus showing superior gas sensing performances toward hydrogen sulfide.

Polymersomes: A Novel Approach for Cancer Theranostics

Background: In the recent epochs of advancement in the field of oncology, polymersomes- based drug delivery systems have witnessed a significant breakthrough. Nano-sized carriers formed from amphiphilic block-copolymers, have distinctive compositions and structures, enabling them to encapsulate a diverse range of compounds. Objective: This comprehensive review aims to highlight the significant advancements reflecting progress made in the past few decades and their potential in cancer treatments, offering a promising future for improved patient outcomes and as a tool for theranostics. Method: Different approaches for synthesizing nanocarriers with distinct responsive characteristics have been mentioned. Redox-responsive polymersomes are designed, and their self-assembly behavior is studied. pH-responsive are created using specific copolymers, while enzyme-responsive ones are engineered to degrade in the presence of lysosomal enzymes using various approaches like thin-film hydration, nanoprecipitation, etc. Result: Polymersomes have exhibited remarkable breakthroughs in cancer theranostics and addressed various challenges associated with drug targeting, diminishing the toxicity, and related issues, exhibiting advantages such as enhanced stability, prolonged circulation time, and the ability to encapsulate both hydrophilic and hydrophobic substances. Over the past few decades, they have been proven as a breakthrough approach for cancer therapy. Conclusion: Polymersomes present a promising platform for advancing cancer therapeutics and diagnostics, offering a multifunctional approach that combines targeted drug delivery with imaging capabilities. Their versatility makes them valuable tools for researchers and practitioners in the field of medicine.

Bioinspired menstrual blood‐derived stem cells‐conditioned medium/polymersome nanoparticles for the treatment of carbon tetrachloride‐induced acute liver failure in mice

AbstractAcute liver failure is a life‐threatening syndrome, for which liver transplantation is presently the most effective treatment. Unfortunately, such treatment is extremely limited by a shortage of donor organs. Stem cell therapy offers a promising treatment strategy for acute liver failure. Yet, therapeutic efficacy and potential are hampered by administration route and safety concerns. In this work, we fabricated menstrual blood‐derived stem cells‐conditioned medium/polymersome hybrid nanoparticles that were self‐assembled from amphiphilic block copolymers via the direct hydration method and encapsulated therapeutic bioactive factors within the aqueous core of vesicles. The merit of vesicular architecture enabled the loading capacity of distinct proteins and the maintenance of biological activity. These hybrid nanoparticles can be steadily taken up into cytoplasm and promote hepatocyte proliferation in vitro. Prolonged in vivo circulation time brought higher accumulation in livers. The therapeutic nanoparticles alleviated hepatic injury and promoted liver recovery in mice with carbon tetrachloride‐induced liver failure. Considering the feasibility and benefit of the hybrid nanoparticle therapy, it provided a potential strategy to treat acute liver failure.

Designed and tailor-made double hydrophilic block copolymer-graphene nanoplatelet hybrids for reinforcing epoxy thermosets

Because of their propensity to build micellar nanostructures, amphiphilic block copolymers (ABCs) are an appropriate and unique toughening agent for epoxy systems individually on their own and in grafted form. The presence of epoxiphilic and phobic ends in ABCs is responsible for the self-assembly and the micellar structure. Nanofiller-grafted ABCs can effectively enhance the toughness of epoxy via the synergistic interaction of nanofillers and the ABCs. Even though there is sound literature supporting the effect of ABCs in epoxy, the action of double hydrophilic block copolymers (DHBC) in the epoxy matrix is less handled. Hence, the grafting of nanofillers in DHBCs and their subsequent role in tuning the properties of epoxy is a new concept. Hence this paper tries to bridge the gap via studying the effect of grafted fillers based on DHBCs in epoxy matrix. As a result, the current study focuses on the synthesis of double hydrophilic graphene nanoplatelets (rGO-g-DHBC) via nitrogen oxide-mediated polymerization for epoxy toughening application. The prepared rGO-g-DHBC was effectively utilized for epoxy toughening applications, resulting in a 457% improvement in toughness without compromising its inherent tensile strength. The mechanism behind the improved toughness was elucidated with the help of a scanning electron microscope, and the thermal, and rheological characteristics were studied.

A Review Concept on Polymer Micelles

Polymeric micelles present a viable approach for research on drug delivery and targeting. Compared to surfactant micelles, polymeric micelles are nanoscale colloid particles that self-assemble from amphiphilic block co-polymers. Their inner core has the ability to solubilize significant amounts of hydrophobic substances. This article has covered a number of topics regarding polymeric micelles, including their fundamentals, which include their size, shape, chemistry, general characteristics, structure analysis, and mechanism of production. The many kinds of polymeric micelles were also emphasised.

Determination of the individual block lengths of the block copolymers of Poly(trimethylene carbonate) by liquid chromatography at critical conditions

Amphiphilic block copolymers based on poly(trimethylene carbonate) (PTMC) have gained significant attention for biomedical applications owing to their unique degradation characteristics. Ring-opening polymerization (ROP) is the most widely employed method for polymerization of cyclic carbonates, especially for trimethylene carbonate (TMC). Herein, di- and tri-block copolymers of PTMC are synthesized by ROP of TMC using poly(ethylene glycol) monomethyl ether (MeO-PEG) or poly(ethylene glycol) (PEG) as a macro-initiator, respectively. The synthesized products are characterized by size-exclusion chromatography (SEC) and nuclear magnetic resonance spectroscopy (1H NMR) for their molar mass and chemical composition, respectively. However, these techniques are inconclusive about several pertinent aspects of the block copolymers, such as individual block length and unwanted homopolymer content. To address these limitations, liquid chromatography at critical conditions of both PEG and PTMC are employed. Chromatographic critical conditions for PTMC are reported for the first time in the current study. The analysis protocol successfully reveals the individual block lengths of both blocks of the block copolymers, along with the quantification of the unwanted homopolymers in the samples. The individual block lengths and the presence of homopolymers significantly affect the self-assembly capability and drug-loading capacity of amphiphilic block copolymers. Thus, the study divulges important information crucial for the development of structure-property correlations, which is essential for optimizing the performance of these block copolymers in biomedical applications.

Photonic Pigments of Polystyrene-block-Polyvinylpyrrolidone Bottlebrush Block Copolymers via Sustainable Organized Spontaneous Emulsification.

Prior studies on photonic pigments of amphiphilic bottlebrush block copolymers (BBCPs) through an organized spontaneous emulsification (OSE) mechanism have been limited to using polyethylene glycol (PEG) as the hydrophilic side chains and toluene as the organic phase. Herein, a family of polystyrene-block-polyvinylpyrrolidone (PS-b-PVP) BBCPs are synthesized with PVP as the hydrophilic block. Biocompatible and sustainable anisole is employed for dissolving the obtained BBCPs followed by emulsification of the solutions in water. Subsequent evaporation of oil-in-water emulsion droplets triggers the OSE mechanism, producing thermodynamically stable water-in-oil-in-water (w/o/w) multiple emulsions with uniform and closely packed internal droplet arrays through the assembly of the BBCPs at the w/o interface. Upon solidification, the homogeneous porous structures are formed within the photonic microparticles that exhibit visible structural colors. The pore diameter is widely tunable (150∼314 nm) by changing the degree of polymerization of BBCP (69∼110), resulting in tunable colors across the whole visible spectrum. This work demonstrates useful knowledge that OSE can be generally used in the fabrication of ordered porous materials with tunable internal functional groups, not only for photonic applications, but also offers a potential platform for catalysis, sensing, separation, encapsulation, etc.

Self‐assembly imprinting fabrication of shell‐crosslinking fluorescent nanoparticles for the detection of sialic acid

AbstractA new strategy for preparing sialic acid (SA)‐quenching fluorescent nanoparticles by macromolecular self‐assembly and molecular imprinting technique is suggested. An amphiphilic block copolymer polystyrene‐b‐poly(glycidyl methacrylate) (PS‐b‐PGMA) was designed and synthesized. After functionalization, PS‐b‐PGMA was co‐assembled with the template molecule SA to prepare SA‐imprinted fluorescent nanoparticles, named as nano‐FMIPs. In this process, the shell layers of nanoparticles were photo‐crosslinked upon 365 nm UV light to stabilize the recognition site. The size of the crosslinked shell was found to be increased to 420 ± 5 nm by TEM and DLS measurements. After extraction of SA, recognition cavities complementary in shape, size, and chemical function toward the template SA were left on the surface of nano‐FMIPs, which can selectively rebind the target SA in a mixture of structurally similar compounds. It is found that SA can significantly quench the fluorescence intensity of nano‐FMIPs linearly within a concentration range of 1 × 10−2 ~ 2 × 10−6 mol L−1 and a detection limit of 1.55 × 10−6 mol L−1. This strategy provides a new approach for preparing surface‐imprinted nano‐FMIPs for the quantitative detection of SA, and the nano‐FMIPs may have great potential for biomedical application.

Morphological Transformation and Surface Engineering of Glycovesicles Driven by Bioinspired Hydrogen Bonds of Nucleobases.

Glycopolymer-based supramolecular glycoassemblies with signal-driven cascade morphological deformation and accessible surface engineering toward bioinspired functional glycomaterials have attracted much attention due to their diverse applications in fundamental and practical scenarios. Herein, we achieved the cascade morphological transformation and surface engineering of a nucleobase-containing polymeric glycovesicle through exploiting the bioinspired complementary multiple hydrogen bonds of complementary nucleobases. First, the synthesized thymine-containing glycopolymers (PGal30-b-PTAm249) are capable of self-assembling into well-defined glycovesicles. Several kinds of amphiphilic adenine-containing block copolymers with neutral, positive, and negative charges were synthesized to engineer the glycovesicles through the multiple hydrogen bonds between adenine and thymine. A cascade of morphological transformations from vesicles to ruptured vesicles with tails, to worm-like micelles, and finally to spherical micelles were observed via continuously adding the adenine-containing polymer into the thymine-containing glycovesicles. Furthermore, the surface charge properties of these glyconano-objects can be facilely regulated through incorporating various adenine-containing polymers. This work demonstrates the potential application of a unique bioinspired approach to precisely engineer the morphology and surface properties of glycovesicles for boosting their biological applications.

Closely Packed Core-Shell Micelle Structures of Double Hydrophilic Miktoarm Star Copolymers at the Air-Water Interface.

The aggregation behavior of amphiphilic block copolymers at the air-water interface has been extensively studied, but less attention was given to that of star copolymers. In this work, we studied the interfacial aggregation behavior of two double hydrophilic pH- and temperature-responsive miktoarm star copolymers of poly[di(ethylene glycol) methyl ether methacrylate]-poly[2-(dimethylamino)ethyl methacrylate] (PDEGMA3-PDMAEMA3 and PDEGMA4-PDMAEMA7, the subscripts denote arm numbers) with different molecular weights. The effects of subphase pH and temperature on the monolayer isotherms and hysteresis curves of the two star copolymers and the morphologies of their Langmuir-Blodgett (LB) films were studied by the Langmuir film balance technique and atomic force microscopy, respectively. At the air-water interface, the two star copolymers tend to form closely packed micelles. These micelles exhibit a core-shell structure, where the small hydrophobic core consists of cross-linker of ethylene glycol dimethacrylate (EGDMA) and the carbon backbones of PDEGMA and PDMAEMA arms and the short hydrophilic shell is composed of di(ethylene glycol) and tertiary amine side groups. With increasing subphase pH, the surface pressure versus molecular area isotherms shift toward larger mean molecular areas as a result of the enhanced interface adsorption of nonprotonated tertiary amine groups. The isotherm shift of PDEGMA3-PDMAEMA3 monolayers is primarily attributed to high density of tertiary amine groups in the shells, while that of PDEGMA4-PDMAEMA7 is mainly attributed to high density of di(ethylene glycol) groups in the shells. The hysteresis degrees in the monolayers of the two copolymers under alkaline and neutral conditions are greater than those under acidic conditions due to the decreased protonation degree of the tertiary amine groups. At 10 °C, the mobility of the shells is poor and the isotherms are located on the right. Above the lower critical solution temperature, di(ethylene glycol) groups contract, which causes a slight shift of the isotherms toward smaller mean molecular areas.

Neutral Block Copolymer Assisted Gene Delivery using Hydrodynamic Limb Vein Injection.

Three different amphiphilic block copolymer families are synthesized to investigate new opportunities to enhance gene delivery via Hydrodynamic Limb Vein (HLV) injections. First a polyoxazoline-based family containing mostly one poly(2-methyl-2-oxazoline) (PMeOx) block and a second block POx with an ethyl (EtOx), isopropyl (iPrOx) or phenyl substituent (PhOx) is synthesized. Then an ABC poly(2-ethyl-2-oxazoline)-b-poly(2-n-propyl-2-oxazoline)-b-poly(2-methyl-2-oxazoline) triblock copolymer is synthesized, with a thermosensitive middle block. Finally, polyglycidol-b-polybutylenoxide-b-polyglycidol copolymers with various molar masses and amphiphilic balance are produced. The simple architecture of neutral amphiphilic triblock copolymer is not sufficient to obtain enhanced in vivo gene transfection. Double or triple amphiphilic neutral block copolymers are improving the in vivo transfection performances through HLV administration as far as a block having an lower critical solution temperature is incorporated in the vector. The molar mass of the copolymer does not seem to affect the vector performances in a significant manner.

Polysaccharides as a Hydrophilic Building Block of Amphiphilic Block Copolymers for the Conception of Nanocarriers.

Polysaccharides are gaining increasing attention for their relevance in the production of sustainable materials. In the domain of biomaterials, polysaccharides play an important role as hydrophilic components in the design of amphiphilic block copolymers for the development of drug delivery systems, in particular nanocarriers due to their outstanding biocompatibility, biodegradability, and structural versatility. The presence of a reducing end in polysaccharide chains allows for the synthesis of polysaccharide-based block copolymers. Compared with polysaccharide-based graft copolymers, the structure of block copolymers can be more precisely controlled. In this review, the synthesis methods of polysaccharide-based amphiphilic block copolymers are discussed in detail, taking into consideration the structural characteristics of polysaccharides. Various synthetic approaches, including reductive amination, oxime ligation, and other chain-end modification reactions, are explored. This review also focuses on the advantages of polysaccharides as hydrophilic blocks in polymeric nanocarriers. The structure and unique properties of different polysaccharides such as cellulose, hyaluronic acid, chitosan, alginate, and dextran are described along with examples of their applications as hydrophilic segments in the synthesis of amphiphilic copolymers to construct nanocarriers for sustained drug delivery.

Temperature-Sensitive Materials for Oil and Gas Drilling Applications.

With the vigorous development of the petroleum industry, improving the efficiency of oil and gas exploitation has become an important issue. Temperature-sensitive materials show great potential for application in the development and production of oil and gas fields due to their unique temperature-responsive properties. This paper reviews the application of temperature-sensitive materials in oil and gas drilling and introduces the characteristics of three types of temperature-sensitive materials: N-substituted acrylamide polymers, amphiphilic block copolymers, and peptides. Because these materials can change their physical state at specific temperatures, this paper discusses in detail the role of various temperature-sensitive materials as plugging agent, thickener, oil displacing agent, flocculant, and tackifier in oil and gas field operations, as well as the mechanism of action and performance of temperature-sensitive materials in practical oil and gas drilling operations. As we have not yet seen relevant similar literature, this paper aims to discuss the innovative application of temperature-sensitive materials in the oil and gas drilling process, and at the same time points out the problems in the current research and applications as well as future development directions. Through analysis and comparison, we provide an efficient and environmentally friendly materials selection option for the petroleum industry in order to promote the progress and sustainable development of oil and gas extraction processes.

Synthesis of PEG-Polycycloether Block Copolymers: Poloxamer Mimics Containing a Rigid Helical Block.

Poloxamers are amphiphilic block copolymers consisting of poly(ethylene glycol) (PEG) and poly(propylene glycol) segments. Their self-assembly and interfacial properties are tied to the relative hydrophilicity and hydrophobicity of each block and can therefore be adjusted by changing block lengths. Here, a series of PEG-polycycloether block copolymers is synthesized that have the same structure as a poloxamer, but they encompass a rigid polycyclic backbone as the hydrophobic block. A variety of polymer structures are synthesized, for example diblock or triblock architectures, with/without olefinic units, atactic or isotactic backbone, and different block lengths. Due to their amphiphilicity, self-assembly into spherical aggregates (diameters ranging from 64 to 132nm) at low concentrations (critical aggregation concentration as low as 0.04mgmL-1) is observed in water. Low surface tensions (as low as 26.7 mNm-1) are observed as well as the formation of stable high internal phase emulsions (HIPEs) irrespective of the oil/water ratio. This contrasts with the properties of the commonly used poloxamers P188 or P407 and illustrates the significance of the rigid polycycloether block. These new colloidal properties offer new prospects for applications in emulsion formulations for biomedicine, cosmetics, and the food industry.