Thermo-/pH-Dual-Sensitive PEG/PAMAM Nanogel: Reaction Dynamics and Plugging Application of CO2 Channeling

Smart hydrogels, owing to their exceptional viscoelastic and deformable capacity in response to environmental stimulation involving temperature and pH, have been successfully applied in oilfields for purposes such as water and/or gas shutoff treatments. However, the CO₂ breakthrough problem in low permeability reservoirs has not been well solved. In this work, a rheological method-based Avrami dynamics model and Dickinson dynamics model were employed to investigate the dynamic gelation process of thermo-/pH-dual-sensitive PEG/PAMAM nanogels to further our understanding of the microstructure of their gelation and pertinence plugging application. Plugging experiments were performed by alternating injections of CO₂ and hydrogel solution in a slug type on three fractured low permeability cores with a backpressure of 13 MPa. The nanogels presented a secondary growth pattern from three to one dimension from micrometer to nanometer size with a morphological transformation from a sphere to an irregular ellipsoid or disk shape. The phase transition temperature was 50 °C, and the phase transition pH was 10. If both or either were below these values, the hydrogel swelled; otherwise, it shrank. Plugging results show that the plugging efficiency was higher than 99%. The maximum breakthrough pressure was 19.93 MPa, and the corresponding residual pressure remained 17.64 MPa for a 10 mD core, exhibiting great plugging performance and high residual resistance after being broken through by CO₂.

Development of a Fluorescent Nanofibrous Template by In Situ SNAr Polymerization of Fluorine-Containing Terphenyls with Aliphatic Diols: Self-Assembly and Optical and Liquid Crystal Properties

Stimulus-responsive supramolecular organogels have been broadly studied, but the assembly of a liquid crystalline organogel with a thermoreversible response remains a challenge. This could be attributed to the difficulty of designing organogelators with liquid crystalline properties. Nucleophilic aromatic substitution (S_NAr) has been utilized to produce a diversity of pentafluorobenzene-containing aromatics, which are very regioselective to para positions. Those pentafluorobenzene-functionalized aromatics have been ideal compounds for the preparation of calamitic liquid crystals. In this context, novel fluoroterphenyl-containing main-chain polyether (FTP@PE) was synthesized using in situ S_NAr polymerization as a convenient and effective synthetic strategy toward the development of fluorescent liquid crystals bearing fluoroterphenyl and ether groups. The fluoroterphenyl unit was synthesized by Cu(I)-supported decarboxylation cross-coupling of potassium pentafluorobenzoate and 1,4-diiodobenzene. The chemical structures of FTP@PE were studied with ¹H/¹³C/¹⁹F nuclear magnetic resonance and infrared spectra. The liquid crystal mesophases were determined with differential scanning calorimetry and polarizing optical microscopy. Ultraviolet-visible absorbance and emission spectral profiles showed solvatochromic activity. The nanofibrous morphologies were studied with a scanning electron microscope. The organogels of FTP@PE were developed in a number of solvents via van der Waals attraction forces of aliphatic moieties and π stacking of fluoroterphenyl groups. They demonstrated thermoreversible responsiveness.

Transparency- and Repellency-Enhanced Acrylic-Based Binder for Stimuli-Responsive Road Paint Safety Improvement Technology

In the current study, an acrylic polymer binder applicable to road signs was successfully developed by mixing various acrylic, acrylate-type, and photoinitiator-based monomer species at different acrylate series/silicone acrylate ratios. An amorphous acrylic monomer was used, and the distance between the polymers was increased to improve transparency. The binder was designed with the purpose of reducing the yellowing phenomenon due to resonance by excluding the aromatic ring structure, which is the main cause of yellowing. The optical properties of the binder were determined according to the content of n-butyl methacrylate/methyl methacrylate and the composition of the crosslinking agent in the formulation. Allyl glycidyl ether and dilauroyl peroxide were used to improve the yellowing problem of benzoyl peroxide, an aromatic photoinitiator. Adding a silicone-based trivalent acrylic monomer, 3-(trimethoxysilyl)propyl methacrylate (TMSPMA), was also found to have a significant effect on the transparency, shear properties, and water resistance of the binder. When 15 wt% TMSPMA was added, the best water repellency and mechanical properties were exhibited. The surface morphology of the improved binder and the peeling part were confirmed using field emission scanning electron microscopy. The acrylic polymer developed in this study can be applied in the coating and adhesive industries.

Acetal-Based Functional Epoxide Monomers: Polymerizations and Applications

Protecting group chemistry is essential for various organic transformation and polymerization processes. In particular, conventional anionic ring-opening polymerization (AROP) often requires proper protecting group chemistry because it is typically incompatible with most functional groups due to the highly basic and nucleophilic conditions. In this context, many functional epoxide monomers with proper protecting groups are developed, including the acetal group as a representative example. Since the early introduction of ethoxyethyl glycidyl ether, there is significant development of acetal-based monomers in the polyethers. These monomers are now utilized not only as protecting groups for hydroxyl groups under AROP conditions but also as pH-responsive moieties for biomedical applications, further expanding their utility in the use of functionalized polyethers. Recent progress in this field is outlined from their synthesis, polymerization, and biomedical applications.

Interactions and Dynamics in Aqueous Solutions of pH-Responsive Polymers: A Combined Fluorescence and Dielectric Relaxation Study

Interaction and dynamics of aqueous solutions of pH-responsive smart polymers are investigated via steady-state, time-resolved fluorescence emission spectroscopy with the help of external local reporter coumarin 153 (C153), while MHz to GHz dielectric relaxation spectroscopic (DRS) measurement reports the intrinsic medium relaxation features. A series of pH-responsive random copolymers (DPL-DP60) comprising of a pH-responsive moiety 2-((leucinyl)oxy)ethyl methacrylate (l-Leu-HEMA) and hydrophobic methyl methacrylate (MMA) are synthesized and characterized. A balance between the pH-responsive (l-Leu-HEMA) and the hydrophobic (MMA) content dictates the phase transition pH, which is found to be ∼5-7 for these aqueous copolymer solutions (1 mg/mL). Dynamic light scattering measurements in aqueous solutions of these polymers reflect a small particle size (∼2-8 nm) at solution pH below their individual phase transition pH, while a large particle size (∼140-340 nm) forms beyond their phase transition pH. No signature of a phase transition pH-driven abrupt change in static and dynamic properties of aqueous polymer solutions has been registered from pH-dependent dielectric relaxation as well as solute (C153)-centric fluorescence measurements. A significant impact of varying the l-Leu-HEMA/MMA segment ratio on steady-state fluorescence emission and rotational anisotropy decay of the fluorophore solute (C153) has been observed. MHz to GHz DRS in aqueous solutions of these pH-responsive polymers reflects bulk water-like dielectric features.

Nitroreductase-responsive polymeric micelles based on 4-nitrobenzyl and AIE moieties for intracellular doxorubicin release

An amphiphilic polymer TNP demonstrated the formation of a nitroreductase-responsive DOX delivery nanoplatform with high sensitivity and selectivity.

Amine-containing diblock terpolymers via AROP: a versatile method for the generation of multifunctional micelles

We herein report the synthesis and block copolymerization via AROP of three glycidyl amine species (PiGA; OPGA, and MPGA) with different hydrophobicity. Micelles formed from these block copolymers respond to changes in pH and H₂O₂ concentration.