Simultaneous switching of two different CO2-switchable amines in the same solution

Most CO2-responsive systems operate by using a base in water that is expected to be mostly deprotonated when under an atmosphere of air and mostly protonated under an atmosphere of CO2. This concept has led to the development of many different CO2-responsive materials such as solvents, polymers, surfactants, and solutes. As CO2-responsive materials research continues, more complex systems may be developed, including systems containing two different bases with different basicities. Understanding the influence each base has on the protonation equilibrium of the other base is important for designing systems in which effective deprotonation and protonation occur. This article presents a model that can predict the solution pH and the % protonation of two different bases at various concentrations under air and CO2. Experimental data was collected to demonstrate the successful simultaneous switching of two amines and to evaluate the accuracy of the predictive model. The simultaneous switching of two different CO2-switchable amines in the same solution was determined to be possible but only if the amine concentrations and basicities are within certain ranges, and only if the pKaH values of the two bases differ by no more than 3 units.

Responsive Polymer Brush Design and Emerging Applications for Nanotheranostics

Responsive polymer brushes are a category of polymer brushes that are capable of conformational and chemical changes in response to external stimuli. They offer unique opportunities for the control of bio-nano interactions due to the precise control of chemical and structural parameters such as the brush thickness, density, chemistry, and architecture. The design of responsive brushes at the surface of nanomaterials for theranostic applications has developed rapidly. These coatings can be generated from a very broad range of nanomaterials, without compromising their physical, photophysical, and imaging properties. Although the use of responsive brushes for nanotheranostic remains in its early stages, in this review, the aim is to present how the systems developed to date can be combined to control sensing, imaging, and controlled delivery of therapeutics. The recent developments for such design and associated methods for the synthesis of responsive brushes are discussed. The responsive behaviors of homo polymer brushes and brushes with more complex architectures are briefly reviewed, before the applications of responsive brushes as smart delivery systems are discussed. Finally, the recent work is summarized on the use of responsive polymer brushes as novel biosensors and diagnostic tools for the detection of analytes and biomarkers.

CO2/N2-Responsive Nanoparticles for Enhanced Oil Recovery During CO2 Flooding

During CO₂ flooding, serious gas channeling occurs in ultra-low permeability reservoirs due to the high mobility of CO₂. The chief end of this work was to research the application of responsive nanoparticles for mobility control to enhance oil recovery. Responsive nanoparticles were developed based on the modification of nano-silica (SiO₂) by 3-aminopropyltrimethoxysilane (KH540) via the Eschweiler-Clark reaction. The proof of concept for responsive nanoparticles was investigated by FT-IR, ¹H-NMR, TEM, DLS, CO₂/N₂ response, wettability, plugging performance, and core flooding experiments. The results indicated that responsive nanoparticles exhibited a good response to control nanoparticle dispersity due to electrostatic interaction. Subsequently, responsive nanoparticles showed a better plugging capacity of 93.3% to control CO₂ mobility, and more than 26% of the original oil was recovered. Moreover, the proposed responsive nanoparticles could revert oil-wet surfaces to water-wet, depending on surface adsorption to remove the oil from the surface of the rocks. The results of this work indicated that responsive nanoparticles might have potential applications for improved oil recovery in ultra-low permeability reservoirs.

Surface-Initiated Atom Transfer Radical Polymerization for the Preparation of Well-Defined Organic-Inorganic Hybrid Nanomaterials

Surface-initiated atom transfer radical polymerization (SI-ATRP) is a powerful tool that allows for the synthesis of organic-inorganic hybrid nanomaterials with high potential applications in many disciplines. This review presents synthetic achievements and modifications of nanoparticles via SI-ATRP described in literature last decade. The work mainly focuses on the research development of silica, gold and iron polymer-grafted nanoparticles as well as nature-based materials like nanocellulose. Moreover, typical single examples of nanoparticles modification, i.e., ZnO, are presented. The organic-inorganic hybrid systems received according to the reversible deactivation radical polymerization (RDRP) approach with drastically reduced catalyst complex concentration indicate a wide range of applications of materials including biomedicine and microelectronic devices.

A new visible light and temperature responsive diblock copolymer

A visible light and temperature responsive diblock copolymer of poly[6-(2,6,2′,6′-tetramethoxy-4′-oxyazobenzene) hexyl methacrylate]-block-poly(N-isopropylacrylamide) (PmAzo-b-PNIPAM) was synthesized via RAFT polymerization by carefully tuning the polymerization conditions.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

pH-Responsive polymers

This review summarizes pH-responsive monomers, polymers and their derivative nano- and micro-structures including micelles, cross-linked micelles, microgels and hydrogels.