Hyperbranched Poly(propylene oxide): A Multifunctional Backbone-Thermoresponsive Polyether Polyol Copolymer

Recent Progress and Future Advances on Aqueous Monovalent-Ion Batteries towards Safe and High-Power Energy Storage

Aqueous monovalent-ion batteries have been rapidly developed recently as promising energy storage devices in large-scale energy storage systems owing to their fast charging capability and high power densities. In recent years, Prussian blue analogues, polyanion-type compounds, and layered oxides have been widely developed as cathodes for aqueous monovalent-ion batteries because of their low cost and high theoretical capacity. Furthermore, many design strategies have been proposed to expand their electrochemical stability window by reducing the amount of free water molecules and introducing an electrolyte addictive. This review highlights the advantages and drawbacks of cathode and anode materials, and summarizes the correlations between the various strategies and the electrochemical performance in terms of structural engineering, morphology control, elemental compositions, and interfacial design. Finally, this review can offer rational principles and potential future directions in the design of aqueous monovalent-ion batteries.

Nonionic Surfactant Properties of Amphiphilic Hyperbranched Polyglycerols

The surfactant properties of amphiphilic hyperbranched polyglycerols (HPGs) were investigated. The HPGs were prepared by ring-opening multibranching polymerization of glycidol using hydrophobic initiators of varying size and structure. The cloud points for all HPG surfactants were found to be >80 °C in deionized water with >1 wt % NaCl. The HPG surfactants with hydrophilic-lipophilic balance values between 16 and 18 were found to form stable octanol/water (o/w) emulsions within a 24 h period. Several surface properties, including critical micelle concentration (CMC), efficiency of surface tension reduction (pC₂₀), effectiveness of surface tension reduction (γ_CMC), surface excess concentration at the CMC (Γ_max), minimum area/molecule at the interface (A_min), and the CMC/C₂₀ ratio of the HPG surfactants were measured in deionized water at 22.6 °C. In general, increasing HPG size was marked by an increase in minimum surface area per molecule (A_min) at the aqueous liquid/air interface. This increase in size also led to lower CMC and greater pC₂₀ values of HPG surfactants prepared with Tergitol 15-S-7 initiator (HPG 5a-5d), a commercially available ethylene glycol oligomer with a branched hydrophobic tail.

Amphiphilic hyperbranched polymers: synthesis, characterization and self-assembly performance

Abstract

A series of amphiphilic hyperbranched polymers (AHP-s, the “s” refers to the algebra of AHP) were synthesized by the reaction between hydroxyl-terminated hyperbranched polymers (HBP-s, the “s” refers to the algebra of HBP) and palmitoyl chloride. FTIR, NMR and GPC were used to determine the structure of AHP-s, the results showed that AHP-s exhibits core-shell structure. The thermal properties of polymers were investigated by DSC and TGA. It was found that AHP-2, AHP-3 and AHP-4 display higher thermal stability than AHP-1 (AHP-1, AHP-2, AHP-3 and AHP-4 represent the first, second, third and fourth generation AHP, respectively). Furthermore, the self-assembly performance of AHP-s in THF solvent was investigated by TEM and SEM. Finally, the encapsulation capacity of the AHP-s for methyl orange (MO) was explored at different concentrations of AHP-s and pH conditions. It was found that AHP-s is capable of accommodating hydrophilic guest MO. Moreover, the higher generation of AHP-s, the stronger encapsulation capacity obtained. And the encapsulation capacity closely associated with the pH of encapsulation system.

Graphical abstract

Synthesis of novel polyethers with abundant reactive sites and diverse skeletons based on the ring-opening reaction of D–A cyclopropanes

Based on the ring-opening reaction of D–A cyclopropanes, a facile synthesis of novel polyethers is developed with molecular weights up to 17.7 kg mol⁻¹.

Synthesis of Novel pH-Tunable Thermoresponsive Hydroxyl-Terminated Hyperbranched Polyether

In this study, a new pH-tunable thermoresponsive hydroxyl-terminated hyperbranched polyether (HTHP 2) was successfully prepared via a one-pot cationic polymerization technique and postmodification. In the first step, hydroxyl-terminated hyperbranched polyether containing double bonds (HTHP 1) were synthesized. Then, through thiol-ene "click" reaction, pH-responsive carboxyl groups were introduced to the target polymer of HTHP 2. The products were characterized via Fourier-transform infrared spectra (FTIR), nuclear magnetic resonance (NMR), and size-exclusion chromatography-multiangle laser light scattering (SEC-MALLS). Moreover, dynamic light scattering (DLS) and UV-Vis spectroscopy was employed to study the pH- and thermoresponsiveness in detail. Results showed that HTHP 2 possessed typical pH-controllable thermoresponsive behavior. By regulating the solution pH value range 3.0-5.4, LCST of HTHP 2 could be changed from 12.8 to 68.0 °C. Meanwhile, the cell viabilities of A549 cells were more than 80% for in vitro cytotoxicity tests of HTHP 2, suggested that HTHP 2 polymers are of good biocompatibility for up to 24 h.

LCST-Type Hyperbranched Poly(oligo(ethylene glycol) with Thermo- and CO2 -Responsive Backbone

A novel hyperbranched lower critical solution temperature (LCST) polymer with sharp temperature and CO₂ -responsive behaviors is presented in this study. The target polymer of hyperbranched poly(oligo(ethylene glycol) (HBPOEG) is constructed using POEG as the backbone and tertiary amines as branch points. Phase transition of HBPOEG in aqueous solution is investigated by heating and cooling the system; the results indicate that HBPOEG in aqueous solution has a concentration-dependent phase transition behavior with excellent repeatability. Moreover, LCST of HBPOEG can be tuned by bubbling CO₂ into the solution, as the tertiary amines can be protonated and the solubility of the polymer would increase by bubbling CO₂ into the system, leading to an increase of LCST of the polymer. Further bubbling N₂ to remove CO₂ can reversibly turn back the LCST to its original value. This backbone-based hyperbranched LCST polymer with both CO₂ and temperature responsiveness can be applied in application areas like drug delivery, gene transfection, functional coatings, etc.

Synthesis of multi-arm star thermo-responsive polymers and topology effects on phase transition

Linear and star thermo-responsive polymers of poly(N-acryloylsarcosine methyl ester) [(PNASME)_n] and poly(N-isopropylacrylamide) [(PNIPAM)_n] with arm number n = 1, 2, 3 and 4 were synthesized following a core-first method via solution RAFT polymerization employing a series of mono- and multi-functional chain transfer agents.

Hyperbranched polyglycerol derivatives exhibiting normal or abnormal thermoresponsive behaviours in water: facile preparation and investigation by turbidimetry and fluorescence techniques

Polymers exhibiting an abnormal thermoresponsive behaviour, in which increase in the polymer concentration in water leads to an increase in the phase transition temperature, are few, and no plausible strategy has been addressed to prepare these polymers. For illuminating a feasible common strategy to prepare polymers with an abnormal thermoresponsive behaviour, in this study, we systematically prepared a series of hyperbranched polyglycerol (HPG) derivatives through a facile esterification reaction between HPG and aliphatic acids having different carbon numbers (X). Turbidimetry measurements demonstrate that thermoresponsive HPGs can be obtained only when HPGs are conjugated with aliphatic units of X ≤ 8. The conjugation of HPG with aliphatic units of X ≤ 4 resulted in thermoresponsive HPGs with a normal thermoresponsive behaviour. For the preparation of thermoresponsive HPGs with an abnormal thermoresponsive behaviour, X should be controlled in the range of 5-8. Fluorescence measurements with nile red as the fluorescent probe demonstrate that the existence of relatively strong hydrophobic interaction is a key factor to ensure that the polymer exhibits an abnormal thermoresponsive behaviour in water. Moreover, turbidimetry and fluorescence techniques are complementary for measuring the phase transition behaviour and suitable for different polymer concentration regions.

Amphiphilic hyperbranched polyglycerols in a new role as highly efficient multifunctional surface active stabilizers for poly(lactic/glycolic acid) nanoparticles

Amphiphilic hyperbranched polyglycerols synthesized with alkyl alcohol initiators are efficient surfactants and stabilizers for poly(lactic/glycolic acid) nanoparticles, which offer various new possibilities for surface functionalized nanosystems.

Stimuli-responsive hyperbranched poly(amidoamine)s integrated with thermal and pH sensitivity, reducible degradability and intrinsic photoluminescence

Stimuli-responsive HPA-C4s integrated with thermal and pH sensitivity, reducible degradability and intrinsic photoluminescence were successfully prepared and characterized.

Preparation of water-soluble hyperbranched polymers with tunable thermosensitivity using chain-growth CuAAC copolymerization

Thermoresponsive hyperbranched polymers with dangling oligo(ethylene oxide) chain on every monomer unit were constructed using the chain-growth copper-catalyzed azide–alkyne cycloaddition (CuAAC) copolymerization of two AB₂-F monomers.

Polymerization of Ethylene Oxide, Propylene Oxide, and Other Alkylene Oxides: Synthesis, Novel Polymer Architectures, and Bioconjugation

The review summarizes current trends and developments in the polymerization of alkylene oxides in the last two decades since 1995, with a particular focus on the most important epoxide monomers ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). Classical synthetic pathways, i.e., anionic polymerization, coordination polymerization, and cationic polymerization of epoxides (oxiranes), are briefly reviewed. The main focus of the review lies on more recent and in some cases metal-free methods for epoxide polymerization, i.e., the activated monomer strategy, the use of organocatalysts, such as N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) as well as phosphazene bases. In addition, the commercially relevant double-metal cyanide (DMC) catalyst systems are discussed. Besides the synthetic progress, new types of multifunctional linear PEG (mf-PEG) and PPO structures accessible by copolymerization of EO or PO with functional epoxide comonomers are presented as well as complex branched, hyperbranched, and dendrimer like polyethers. Amphiphilic block copolymers based on PEO and PPO (Poloxamers and Pluronics) and advances in the area of PEGylation as the most important bioconjugation strategy are also summarized. With the ever growing toolbox for epoxide polymerization, a "polyether universe" may be envisaged that in its structural diversity parallels the immense variety of structural options available for polymers based on vinyl monomers with a purely carbon-based backbone.

Water-soluble and redox-responsive hyperbranched polyether copolymers based on ferrocenyl glycidyl ether

Hyperbranched polymers based on glycidol and ferrocenyl glycidyl ether are prepared, characterized, and their redox behavior in water is studied and quantified with Mößbauer spectroscopy.

Hyperbranched poly(triazole) with thermal and metal ion dual stimuli-responsiveness

Hyperbranched poly(triazole) bearing oligo(ethylene glycol) terminal groups is dual stimuli-responsive to thermal conditions and metal ions and is capable for the selective absorption of Ag⁺ ion on tuning temperature.

Novel pH-tunable thermoresponsive polymers displaying lower and upper critical solution temperatures

Novel pH-tunable thermoresponsive 3-azido-2-hydroxypropyl methacrylate-based polymers displaying LCST and UCST in phosphate buffer solutions were successfully synthesized by ATRP.

Bioapplications of hyperbranched polymers

The recent research progress in biological and biomedical applications of hyperbranched polymers has been summarized in this review.

Nanodynamics of dendritic core-multishell nanocarriers

The molecular dynamics of polymeric nanocarriers is an important parameter for controlling the interaction of nanocarrier branches with cargo. Understanding the interplay of dendritic polymer dynamics, temperature, and cargo molecule interactions should provide valuable new insight for tailoring the dendritic architecture to specific needs in nanomedicine, drug, dye, and gene delivery. Here, we have investigated polyglycerol-based core-multishell (CMS) nanotransporters with incorporated Nile Red as a fluorescent drug mimetic and CMS nanotransporters with a covalently bound fluorophore (Indocarbocyanine) using fluorescence spectroscopy methods. From time-resolved fluorescence depolarization we have obtained the rotational diffusion dynamics of the incorporated dye, the nanocarrier, and its branches as a function of temperature. UV/vis and fluorescence lifetime measurements provided additional information on the local dye environment. Our results show a distribution of the cargo Nile Red within the nanotransporter shells that depends on solvent and temperature. In particular, we show that the flexibility of the polymer branches in the unimolecular state of the nanotransporter undergoes a temperature-dependent transition which correlates with a larger space for the mobility of the incorporated hydrophobic drug mimetic Nile Red and a higher probability of cargo-solvent interactions at temperatures above 31 °C. The measurements have further revealed that a loss of the cargo molecule Nile Red occurred neither upon dilution of the CMS nanotransporters nor upon heating. Thus, the unimolecular preloaded CMS nanotransporters retain their cargo and are capable to transport and respond to temperature, thereby fulfilling important requirements for biomedical applications.

Modification of lignin with dodecyl glycidyl ether and chlorosulfonic acid for preparation of anionic surfactant

Improving the surface activity of lignin through chemical modification for preparation of anionic surfactant.

Fabrication of thermoresponsive nanogels by thermo-nanoprecipitation and in situ encapsulation of bioactives

Thermo-nanoprecipitation is presented as a versatile, surfactant-free, and mild synthetic method for the preparation of thermoresponsive nanogels and in situ encapsulation of bioactives.

New directions in thermoresponsive polymers

Interest in thermoresponsive polymers has steadily grown over many decades, and a great deal of work has been dedicated to developing temperature sensitive macromolecules that can be crafted into new smart materials. However, the overwhelming majority of previously reported temperature-responsive polymers are based on poly(N-isopropylacrylamide) (PNIPAM), despite the fact that a wide range of other thermoresponsive polymers have demonstrated similar promise for the preparation of adaptive materials. Herein, we aim to highlight recent results that involve thermoresponsive systems that have not yet been as fully considered. Many of these (co)polymers represent clear opportunities for advancements in emerging biomedical and materials fields due to their increased biocompatibility and tuneable response. By highlighting recent examples of newly developed thermoresponsive polymer systems, we hope to promote the development of new generations of smart materials.

Impact of Amino-Functionalization on the Response of Poly(ethylene glycol) (PEG) to External Stimuli

It is shown that amino-functionalization of poly(ethylene glycol) (PEG) with the comonomer N,N-diethyl glycidyl amine (DEGA) triggers the emergence of extraordinary stimuli responsiveness and phase behavior of PEG. In dependence of the solution pH, tapered PEG-co-PDEGA exhibits a highly cooperative two-step inverse phase transition with respect to temperature. The polymer forms dispersed metastable nanoglobules in the medically relevant temperature range around human body temperature. Independently, cloud points can be adjusted between 40 and 90 °C via the pH of the solution. Changing the polymer architecture to a block structure, in pronounced contrast, the polymer exhibits a gradual growth of micelles with temperature until macroscopic aggregation takes place. Thus, through amino-functionalization of PEG, one can precisely control the temperature range and the mechanism of the inverse phase transition of this promising polymer-therapeutics candidate by adjusting solution conditions and polymer topology.