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.
This article describes an experimentally versatile strategy for producing inorganic/organic nanocomposites, with control over the microstructure at the nano‐ and mesoscales. Taking inspiration from ...biominerals, CaCO3 is coprecipitated with anionic diblock copolymer worms or vesicles to produce single crystals of calcite occluding a high density of the organic component. This approach can also be extended to generate complex structures in which the crystals are internally patterned with nano‐objects of differing morphologies. Extensive characterization of the nanocomposite crystals using high resolution synchrotron powder X‐ray diffraction and vibrational spectroscopy demonstrates how the occlusions affect the short and long‐range order of the crystal lattice. By comparison with nanocomposite crystals containing latex particles and copolymer micelles, it is shown that the effect of these occlusions on the crystal lattice is dominated by the interface between the inorganic crystal and the organic nano‐objects, rather than the occlusion size. This is supported by in situ atomic force microscopy studies of worm occlusion in calcite, which reveal flattening of the copolymer worms on the crystal surface, followed by burial and void formation. Finally, the mechanical properties of the nanocomposite crystals are determined using nanoindentation techniques, which reveal that they have hardnesses approaching those of biogenic calcites.
A bioinspired one‐pot method is presented which generates nanocomposites comprising copolymer vesicles and worms occluded within calcite single crystals. Detailed characterization of the nanocomposites shows that the microstructures of the host crystals are controlled by size, shape, and surface chemistry of their copolymer occlusions, giving rise to hardnesses comparable to many calcite biominerals.
The facile synthesis of amphiphilic hyperbranched copolymers with biodegradability generally suffers from sophisticated specific design and multistep preparation procedures integrating different ...synthetic approaches, leading to difficulty and complexity in scalable manufacture and potential biomedical applications. To develop a robust yet facile strategy toward biodegradable hyperbranched amphiphilic copolymers, we reported in this study the design and synthesis of a reducible macromonomer, 2-((2-hydroxyethyl)disulfanyl)ethyl methacrylate-
graft
-polycaprolactone (HSEMA-
g
-PCL). This macromonomer integrates polymerizable vinyl and hydrophobic poly( -caprolactone) (PCL) units
via
a disulfide link, which enables the successful preparation of two types of biodegradable amphiphilic hyperbranched copolymers,
i.e.
, a hyperbranched statistical copolymer
h
-P(OEGMA-
st
-(HSEMA-
g
-PCL)) and a hyperbranched block-statistical copolymer
h
-P(HSEMA-
g
-PCL)-
b
-POEGMA, with an identical polymer composition but different polymer architectures
via
a reversible addition-fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP) process. The controlled synthesis of biodegradable hyperbranched copolymer panels was supported by the modulated degrees of branching (DBs) (0.05-0.14), narrow polydispersity indexes (
) (1.36-1.74) and CTA functionalities (
f
CTA
) (2.4-4.3). Interestingly, the type and size of the resulting self-assembled aggregates depended on the relative content of the P(HSEMA-
g
-PCL) segment in the hyperbranched copolymers. A comparison study on the colloidal stability revealed greater stability of micelles formed by
h
-P(HSEMA-
g
-PCL)-
b
-POEGMA than that of micelle analogues self-assembled from
h
-P(OEGMA-
st
-(HSEMA-
g
-PCL)) because of the stronger steric hindrance of an individual POEGMA block in a block architecture. Therefore, the former micelle formulation with greater stability was chosen as a better nanocarrier for prolonged blood circulation. Doxorubicin (DOX)-loaded
h
-P(HSEMA-g-PCL)-
b
-POEGMA copolymer micelles showed an intracellular reduction-promoted drug release and efficient inhibition of MCF-7 cell proliferation. Taken together, the reducible hydrophobic macromonomer developed herein provides a facile yet robust strategy for biodegradable amphiphilic hyperbranched copolymers, and the block-statistical structure is identified as a better polymer architecture for controlled release applications.
A reducible hydrophobic macromonomer, HEMA-
g
-PCL, developed herein provides a facile yet robust strategy for biodegradable amphiphilic hyperbranched copolymers.
•Poly(2-methyl-1,3-propanediyl succinate) (PMPS) was applied as a soft segment.•PLLA-b-PMPS-b-PLLAs were synthesized as new biodegradable thermoplastic elastomers.•The triblock copolymers showed Tg ...at lower than −20 °C and Tm at around 150 °C.•Their tensile tests demonstrated their low modulus and high elongation.•Their biodegradation tests were performed using enzymes and seawater.
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Triblock copolymers, poly(L-lactide)-b-poly(2-methyl-1,3-propanediyl succinate)-b-poly(L-lactide) (PLLA-b-PMPS-b-PLLA), were synthesized as new biodegradable thermoplastic elastomers by two-step polymerization. In the first step, hydroxy-telechelic poly(2-methyl-1,3-propanediyl succinate) (PMPS) was synthesized from 2-methyl-1,3-propanediol (MP, small excess) and succinic acid (SA) using two-stage reaction of esterification and simple polycondensation processes. In the second step, plant derived L-lactide (LLA) was polymerized using the bifunctional PMPS as a macroinitiator to synthesize PLLA-b-PMPS-b-PLLA triblock copolymers. The structures of the triblock copolymers as well as the PMPS macroinitiator were characterized by NMR and GPC analysis. PMPS is an amorphous polymer with Tg at lower than −24 °C. The triblock copolymers also exhibited low Tg for the PMPS segment at lower than −20 °C as well as Tm at around 150 °C for the PLLA segment. The tensile tests of the triblock copolymers demonstrated their low modulus and high elongation. The biodegradation tests of these polymers were also performed using enzymes and seawater to reveal their biodegradability.
Ionic liquids (ILs), solely composed of cations and anions, are regarded as a novel class of promising liquids, potentially applicable to energy devices, reaction media, separation materials,
etc.
...ILs have also attracted great attention as new media for molecular self-assembly, capable of producing novel soft materials with unique features never observed for conventional soft materials containing organic and aqueous solvents. In this review, we focus on recent developments in block copolymer (BCP) self-assembly in ILs. Self-assembled structures formed by dilute and concentrated BCP solutions in ILs are discussed in detail. Ion gels formed by BCP self-assembly have received special interest because they exhibit excellent physical properties of tunable viscoelasticity and solution processability without impairing the intrinsic properties of ILs, such as nonvolatility, nonflammability, and high ionic conductivity. Applications of ion gels based on BCP self-assembly for electric double layer capacitors, lithium-ion batteries, and electroactive soft actuators are also addressed.
Recent developments in block copolymer self-assembly in ionic liquids are reviewed from both fundamental and applied aspects.
Macromolecular Cross-Metathesis (MCM) reactions on commercial Polybutadiene (PBD) and Polyisoprene (PIP) homopolymers, in the presence of first generation Grubbs and Hoveyda-Grubbs catalysts, are ...reported. 13C-NMR resonances of butadiene(B)/isoprene(I) heterosequences show block-copolymer formation, with blocks longer than a hundred monomer units, even for long reaction times. DSC scans of MCM products show that, with MCM time, PBD crystallinity progressively disappears while the well separated Tg of the two homopolymers merge to an intermediate single Tg. This indicates that PBD and PIP blocks are completely miscible when their lengths are reduced to a few hundred units. 13C NMR spectra also show that, for the considered MCM process, double bond isomerizations are definitely more frequent than heterosequence formations.
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•Induction of miscibility on Polybutadiene/Polyisoprene blends.•Block copolymer formation by Macromolecular Cross-Metathesis.•blends with single Tg, irrespective of the high block length.•Grubbs and Howeyda-Grubbs catalysts for Macromolecular Cross-Metathesis.
A novel linked‐half‐sandwich lutetium–bis(allyl) complex (C5Me4C5H4N)Lu(η3‐C3H5)2 (1) attached by a pyridyl‐functionalized cyclopentadienyl ligand was synthesized and fully characterized. Complex 1 ...in combination with Ph3CB(C6F5)4 exhibited unprecedented dual catalysis with outstanding activities in highly syndiotactic (rrrr>99 %) styrene polymerization and distinguished cis‐1,4‐selective (99 %) butadiene polymerization, respectively. Strikingly, this catalyst system exhibited remarkable activity (396 kg copolymer (molLu h)−1) for the copolymerization of butadiene and styrene. Irrespective of whether the monomers were fed in concurrent mode or sequential addition of butadiene followed by styrene, diblock copolymers were obtained exclusively, which was confirmed by a kinetics investigation of monomer conversion of copolymerization with time. In the copolymers, the styrene incorporation rate varied from 4.7 to 85.4 mol %, whereas the polybutadiene (PBD) block was highly cis‐1,4‐regulated (95 %) and the polystyrene segment remained purely syndiotactic (rrrr>99 %). Correspondingly, the copolymers exhibited glass transition temperatures (Tg) around −107 °C and melting points (Tm) around 268 °C; typical values for diblock microstructures. Such copolymers cannot be accessed by any other methods known to date. X‐ray powder diffraction analysis of these diblock copolymers showed that the crystallizable syndiotactic polystyrene (syn‐PS) block was in the toluene δ clathrate form. The AFM micrographs of diblock copolymer showed a remarkable phase‐separation morphology of the cis‐1,4‐PBD block and syn‐PS block. This represents the first example of a lutetium‐based catalyst showing both high activity and selectivity for the (co)polymerization of styrene and butadiene.
Challenge to a dual: Under the activation of Ph3CB(C6F5)4, a pyridyl‐functionalized cyclopentadienyl lutetium–bis(allyl) complex exhibited unprecedented dual behavior for syndiotactic (rrrr>99 %) styrene polymerization and cis‐1,4‐selective (99 %) butadiene polymerization.
Developing an intelligent drug delivery/release system, which can transport drugs to the target tissues precisely and release drugs timely, is an important challenge in chemotherapy. A multistage ...sensitive drug delivery system is designed by inserting a folate (FA) modified lipid and a pH/temperature dual‐sensitive amphiphilic copolymer into a liposome bilayer. The stretchable copolymer plays a role in protection on FA ligand for more accurate targeting. Then, the stretch ability of the copolymer in the liposome bilayer is verified by using the Langmuir–Blodgett film technique. The interaction between the 1,2‐dipalmitoyl‐sn‐glycerol‐3‐phosphocholine (DPPC) monolayer and hybrid liposomes is found to increase, indicating the FA ligand is exposed due to the copolymer shrinking with increasing temperature. Fluorescence polarization measurements demonstrate that the insertion of the copolymer improves the stability of the liposome and offers pH‐controllability for drug release. As a result, the drug leakage of the hybrid liposome is restrained significantly at pH 7.4, while at an acidic pH, the drug release is accelerated. The designed pH/temperature dual‐sensitive copolymer is expected to provide more precise targeting and environmentally controlled drug release to drug delivery systems based on liposomes.
A pH/temperature dual‐sensitive copolymer, P(MEO2MA90‐co‐OEGMA10)‐PDPA22, is designed and synthesized to have a cloud point temperature of 42.6 °C and a triggering pH value at 6.8. Combining this sensitive copolymer and a tumor‐targeted 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine polyethylene glycol folic acid (DSPE‐PEG‐FA) copolymer with the lipid bilayer, a hybrid liposome system is fabricated to realize accurate targeting and controllable drug release.
Preferential formation of β phase PVDF via an anti-solvent crystallization process. Electrostatic interactions at the boundary layer between dimethyl acetamide and methanol with additives are ...suggested to be the origin of high β phase content in PVDF homopolymer, blends and block copolymers with PMMA.
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•Preferential formation of PVDF β crystalline phase via anti-solvent crystallization.•Ion concentration in methanol as precipitant determines the fraction of β phase PVDF.•Precipitant methanol contains HCl, NaCl, CaCl2, potassium salts or water as additive.•Method applicable to PVDF homopolymer, blends and block copolymers with PMMA.
In this contribution the anti-solvent crystallization of poly(vinylidene fluoride) (PVDF) as well as its blends and block copolymers with poly(methyl methacrylate) (PMMA) is considered. The impact of precipitation conditions such as solvent, precipitant, and its additives on the type of the PVDF crystalline phase is shown. Special attention is paid to the fraction of β crystalline phase in the material. Generally, increased ion concentrations result in higher β phase contents. With sufficient amounts of CaCl2, LiCl, and HCl in methanol almost only the β crystalline phase of PVDF is obtained. The presence of PMMA is not necessarily required for β phase formation.
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