Poly Dimethylaminoethyl Methacrylate Research Articles

Quaternized polydimethylaminoethyl methacrylate polymer brushes functionalized magnetic graphene oxide for efficient removal of diclofenac from complex environments: synthesis, adsorption performance, DFT calculation and mechanism

Diclofenac as one of the most widely used anti-inflammatory drugs has been found in various aqueous environments in recent years. In this work, a quaternized polydimethylaminoethyl methacrylate functionalized polydopamine-coated magnetic graphene oxide (denoted MGO@PDA@PDMAEMA*) was prepared for the efficient removal of diclofenac. The polydopamine (PDA) was coated on MGO and then the dopamine derivative containing surface-initiated polymerization initiator was immobilized on the MGO@PDA by controlling the self-polymerization of dopamine and dopamine derivative. Finally, PDMAEMA brushes were grafted onto MGO@PDA by atom transfer radical polymerization, and quaternization by reacting with bromopropane. The morphology and structure of the MGO@PDA@PDMAEMA* are characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and vibrating sample magnetometer and Zeta potential analysis. The MGO@PDA@PDMAEMA* exhibits the excellent thermal and chemical stability, high zeta potential (54.74 mV) and magnetic responsivity (36.57 emu·g−1), which can be used as an ideal adsorbent for rapid isolation of targets. The adsorption isotherms and kinetics of diclofenac followed well with the Langmuir model and pseudo-second-order kinetic model, respectively. The maximum saturation adsorption capacity from Langmuir model was 1960.8 mg·g−1 under pH 5 at temperature of 293 K, and the removal rate of diclofenac was more than 90% within half an hour. The adsorption and density functional theory demonstrated that the quaternary ammonium ion on the MGO@PDA@PDMAEMA* was the main electrostatic binding site to diclofenac. More importantly, high removal efficiency of diclofenac in the environmental water confirmed the potential of MGO@PDA@PDMAEMA* as a diclofenac adsorbent.

Low fouling/scaling double network thin film composite nanofiltration membranes with improved desalination performance

Conventional poly(piperazineamide) [poly(PIP)] thin film composite (TFC) nanofiltration (NF) membranes undergo severe fouling/scaling and -show low barrier towards heavy metal ions and organic solutes. Herein, we report the preparation of double network (DN) TFC NF membranes to address these issues. In situ interfacial polymerization between PIP + poly(2-dimethyl aminoethyl)methacrylate (PDMA) and trimesoyl chloride+activated dihalide provides DN-TFC NF membranes. Formation of DN leads to the lowering of negative charge and narrowing down the pore size distribution of the membranes. PEGylated DN-TFC membranes have been prepared using copolymers of PEG and PDMA to demonstrate the adaptability of this chemistry and to increase the antifouling property. The DN-TFC membranes show water permeance of 7.9–8 L m−2 h−1 bar−1 and higher rejection of MgCl2 (90–94 %), Co2+ (96–98 %) and bisphenol A (91–94 %) as compared to that of the pristine (74 %, 70 % and 80 %) and the reported negatively charged (9–83 %, 60 % and 48–97.6 %) NF membranes. DN-TFC membranes show Na2SO4 rejection of ∼98 %, close to the reported membranes (98–99 %). The fouling and scaling resistant behaviors of the DN-TFC membranes (Flux recovery ratio = 90–94 % and 93–95 %) are greatly enhanced as compared to that of the pristine membrane (∼82 % and 76 %). DN-TFC membranes show great promises for the purification of water.

A soluble pH-responsive host-guest-based nanosystem for homogeneous exosomes capture with high-efficiency

Exosomes offer ideal biomarkers for liquid biopsies. However, high-efficient capture of exosomes has been proven to be extreme challenging. Here, we report a soluble pH-responsive host-guest-based nanosystem (pH-HGN) for homogeneous isolation of exosomes around physiological pH. The pH-HGN consists of two specifically functionalized modules. First, a pH-responsive module, poly-dimethylaminoethyl methacrylate, provides homogeneous capture circumstances and sharp pH-triggered self-assembly separation in aqueous solution to improve capture efficiency and reduce nonspecific adsorption. Second, a host-guest module, poly-acrylamide azobenzene and β-cyclodextrin linked with exosomes-specific antibody, could act as the "cleavable bridge" to specific capture and subsequent rapid release of captured exosomes through host-guest interaction between β-cyclodextrin and AAAB moieties. The pH-HGN offered high capture efficiencies for exosomes from two different cell lines, which were 90.2% ± 0.28% and 87.0% ± 4.6% for H1299 and MCF-7 cell-derived exosomes, respectively. The purity of isolated exosomes was (1.49 ± 0.71) × 1011 particles/µg, which was 4.1 times higher compared with the gold standard ultracentrifugation (UC) method. Furthermore, the isolated exosomes via the pH-HGN can preserve well integrity and biological activity. The developed pH-HGN was further successfully applied to differentiate lung cancer patients from healthy persons. These findings indicated that pH-HGN is a promising strategy in exosomes-based research and downstream applications.

Biocompatible hierarchical zwitterionic polymer brushes with bacterial phosphatase activated antibacterial activity

Hierarchical polymer brushes have been considered as an effective and promising method for preventing implant-associated infections via multiple antibacterial mechanisms. Herein, a bacterial phosphatase responsive surface with hierarchical zwitterionic structures was developed for timely dealing with the polymeric implant-associated bacterial infection. The hierarchical polymeric architecture was subtly realized on model polypropylene (PP) substrate by sequential photo living grafting of poly (2-(dimethylamino) ethyl methacrylate (PDMAEMA) bottom layer and zwitterionic poly (sulfobetaine methacrylate) (PSBMA) upper layer, followed by the conversion of the PDMAEMA into the zwitterionic structure via successive quaternization and phosphorylation reactions. Owing to shielding the bottom polycations, the hierarchical zwitterionic polymer brushes guaranteed the surface with the optimal biocompatibility under the normal physiological environment. Once bacteria are invaded, the surface bactericidal activity of the bottom layer can be rapidly and automatically activated owing to the transition triggered by bacterial phosphatase from zwitterion to polycation. Additionally, ameliorated by the upper layer, the hierarchical surface showed obvious adhesion resistance to dead bacterial cells and notably migrated the cytotoxicity of exposed polycation after completion of the bactericidal task. As a proof-of-principle demonstration, this self-adaptive hierarchical surface with sensitive bacterial responsiveness and biocompatibility showed great potential in combating hernia mesh-related infection. This work provides a promising and universal strategy for the on-demand prevention of medical device-associated infections.

Selectively triggered cell detachment from poly(N-isopropylacrylamide) microgel functionalized substrates

The stimuli-triggered cell attachment/detachment from responsive polymer-coated surfaces is influenced by several parameters including electrostatic interactions, wettability and swelling of the polymer coating. Herein, the supported dual thermo- and pH-responsive cationic poly(N-isopropylacrylamide) microgel, surface-functionalized with polyethylene glycol (PEG) or poly-2-dimethylaminoethylmethacrylate (PDMAEMA), were used as substrates to investigate the role of these parameters on the cell behavior. The microgel were covalently immobilized on glass coverslips and their stimuli-triggered cell detachment ability towards cultured bEnd.3, MCF7 and U138 cell lineages was investigated. The microgel surface-functionalized with PEG chains presented cell adhesion and proliferation rates comparable to controls, while providing the best thermo-triggered detachment performance with MCF7 and U138 cells. This behavior was associated with a preserved hydrophilic character of the microgel surface regardless of the temperature and pH. The swelling behavior of all microgels tuned by pH gave rise to significant cellular detachment only for U138 cells. However, bEnd.3 cell detachment could not be triggered neither by temperature nor pH, regardless of the microgel surface coating.

Multiresponsive Microgels: Toward an Independent Tuning of Swelling and Surface Properties.

Dual-responsive poly-(N-isopropylacrylamide) (PNIPAM) microgels surface-functionalized with polyethylene glycol (PEG) or poly-2-dimethylaminoethyl methacrylate (PDMAEMA) were developed to enable the swelling behavior and surface properties of the microgels to be tuned independently. The thermo-triggered swelling and pH-triggered surface properties of the microgels were investigated in aqueous suspensions using dynamic light scattering and on substrates using the surface forces apparatus. Grafting polymer chains on the microgel surface did not impede the thermo-triggered swelling behavior of the microgels in suspensions and immobilized on substrates. An unprecedented decoupling of the swelling behavior and surface properties could be obtained. More particularly, the thermo-triggered swelling behavior of the PNIPAM underlying microstructure could be tuned below and above the phase transition temperature with no change in the surface potential and adhesion provided by the surface non-responsive PEG.

Preparation of a Novel CO2-Responsive Polymer/Multiwall Carbon Nanotube Composite

A CO2-responsive composite of multiwall carbon nanotube (MWCNT) coated with polydopamine (PDA) and polydimethylamino-ethyl methacrylate (PDMAEMA) was prepared. The PDA was first self-polymerized on the surface of carbon nanotube. 2-bromoisobutyryl bromide (BiBB) was then immobilized by PDA and then initiated the ATRP of DMAEMA on the carbon nanotube surface. The resulting composite was characterized by Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The CO2-responsive test was performed by bubbling CO2 into the mixture of MWCNT-PDA-PDMAEMA composite in water. A well-dispersed solution was obtained and the UV-Vis transmittance decreased dramatically. This is attributed to the reaction between PDMAEMA and CO2. The formation of ammonium bicarbonates on the surface of carbon nanotubes leads to the separation of nanotube bundles. This process can be reversed as the removal of CO2 by bubbling N2.

Ultrasonic responsive nanostructures prepared by self-assembly of polymeric single-chain nanoparticles

ABSTRACT Tadpole-like single-chain particle (TSCP) with a crosslinked PDMAEMA (poly(2-dimethylaminoethyl methacrylate)) chain as the head and a tethered POEGMA (oligo(ethylene glycol) monomethyl ether methacrylate) chain as the tail was fabricated by intra-chain crosslinking of PDMAEMA chain of the copolymer POEGMA-b-PDMAEMA (POD). In the selective solvent for the tail, TSCPs formed worm-like micelles, thin films and tubular vesicles in DMF/H2O (1/4, v/v). Different from the traditional one-shot response to ultrasonic treatment, the tubular vesicles underwent rapid structural transformations to spherical vesicles under gentle ultrasonic treatment and fragments under an enhanced ultrasonic treatment. The unique multi-level ultrasonic response behaviour makes the assemblies promising drug carriers featured with the remote and stepwise controlling release of drugs.

Preparation of zwitterionic microspheres of PDMAEMA-b-PMAA by RAFT dispersion polymerization in alcohol, their pH-sensitivity in water, and self-assembly in KCl solution

Zwitterionic microspheres of poly2-(dimethylamino) ethyl methacrylate (PDMAEMA) block polymethacrylic acid (MAA) were prepared by RAFT dispersion polymerization in alcohols. 4-Cyano-4-(phenylcarbonothioylthio) pentanoic acid (CPDB) was used as the RAFT agent. 2,2′-Azobis(2,4-dimethyl) valeronitrile (V65) was used as the initiator, and PDMAEMA-CPDB was used as the macro-chain transfer agent (CTA). 1HNMR was applied to determine the polymerization degrees of both PDMAEMA-CTA and PDMAEMA-b-PMAA. SEM, dynamic light scattering (DLS), and small-angle X-ray diffraction (SAX) were employed to characterize the microspheres. It was observed that the polarity of alcohols impacted the partition of MAA and V65 between the mini-droplets of PDMAEMA-CTA/MAA complexes and the continuous phase, thereby affected on the diameters of microspheres, the total conversion of MAA, and the polymerization degree of PMAA in the copolymers. For example, in methanol, the smallest diameter and polymerization degree of PMAA in the block copolymers were obtained, whereas the total conversion of MAA of the RAFT polymerization system was the highest. Most of RAFT polymerization of MAA occurred nearby PDMAEMA-CTA chains; thus, PDMAEMA-CTA acted as a template to regulate the length of PMAA in the copolymers. pH-sensitive characteristics of microspheres were dependent to the extra length of PDMAEMA-CTA, i.e., the difference of lengths between two blocks. When the length of PMAA was too short, e.g., PDMAEMA600-b-PMAA87, or the length of PMAA was closed to that of PDMAEMA, e.g., PDMAEMA79-b-PMAA93 and PDMAEMA102-b-PMAA131, the amphoteric characteristics of microspheres disappeared. The self-assembly behavior of diblock copolymers in KCl alcohol-water solution was also determined by the extra length of PDMAEMA. Microspheres turned into nanofibers or nano-ribbons, but for PDMAEMA600-b-PMAA87, the microspheres maintained their original spheric morphology. These results indicated that the charge-screening effects of salts played the key roles in the self-assembly.

Temperature-responsive mesoporous silica nanoreactor with polymer gatings immobilized surface via a ‘grafting-to’ approach as peroxidase-like catalyst

Abstract An efficient gold decorated mesoporous silica/polymer hybrid nanoreactor was prepared for catalytic applications. The Huisgen cyclo-addition method was used to immobilize poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA) gatings on the surface of the mesoporous silica using a ‘grafting-to’ approach. The catalyst particles exhibited well-ordered mesoporous structural integrity with well-dispersed gold nanoparticles showing resonance plasma absorption. The catalyst exhibited efficient peroxidase like activity for the oxidation of 3,3,5,5-tetramethylbenzidine in the presence of H2O2, which was found to be in consistent with the standard Michaelis-Menten kinetics. The change in the catalytic activity with temperature was evaluated using 4-nitrophenol reduction as the model reaction. The catalyst showed nonlinear variation of the rate constants with temperature. A sharp decrease in the rate constant was observed above 35 °C due to the thermodynamic volume phase transition of the grafted PDMAEMA chains. In contrast, a typical Arrhenius-type dependence of the rate constant on temperature was observed above and below the transition temperature of PDMAEMA.

Surface modification of SiO2 nanoparticles with PDMAEMA brushes and Ag nanoparticles as antifungal coatings using electron beam assisted synthesis

A model functional, stable and dispersible silver nanoparticles (AgNPs) immobilized on polymeric brushes grafted silica nanoparticle is proposed as antimicrobial additive for coating applications. The aim of this work is to modify silica nanoparticles (SiO2NPs) with poly 2-(dimethyl amino) ethyl methacrylate (PDMAEMA) brushes for template synthesis and immobilization of AgNPs using electron beam assisted grafting and reduction reactions. The PDMAEMA moieties were grafted onto vinyltrimethoxysilane (VTMS) modified SiO2NPs using pre-irradiation and peroxidation grafting approaches. Several grafting parameters, i.e., pre-irradiation doses, DMAEMA monomer concentrations, reaction times and temperatures, were studied to optimize degree of grafting (DG). AgNPs were constructed on the SiO2NPs through the grafted PDMAEMA brushes as polymer shell template. AgNPs were successfully created on SiO2NPs-VTMS-PDMAEMA by electron-induced reduction reaction. DG of the PDMAEMA on SiO2NPs-VTMS was confirmed by gravimetric measurement, FTIR, TGA, TEM, FE-SEM. The nanostructure information and AgNPs immobilization were revealed by UV–Vis, TEM, SEM-EDX and XRD. The optimized grafting degree to obtain desirable appearance was 190%. The AgNPs (6 ± 2 nm) on SiO2NPs-VTMS-PDMAEMA exhibited the characteristic UV-vis absorbance of spherical Ag nanoarchitecture around 418 nm. The AgNPs immobilized SiO2NPs-VTMS-PDMAEMA efficiently inhibited the growth of fungi, i.e., Aspergillus niger and Syncephalatrum racemosum found on building materials.

Effect of DMAEMA content and polymerization mode on morphologies and properties of pH and temperature double-sensitive cellulose-based hydrogels

Double responsive cellulose/ poly 2-(dimethylamino) ethyl methacrylate (PDMAEMA) hydrogels were prepared through in situ radical polymerization. The results from Fourier transform infrared spectroscopy, scanning electron microscopy, mechanical property testing, swelling experiments as well as thermogravimetric analysis demonstrated that 2-(dimethylamino) ethyl methacrylate (DMAEMA) content and polymerization modes played a decisive role in hydrogel’s structure. Firstly, with increasing DMAEMA content, the texture of hydrogel became softer. The incorporation of relatively hard cellulose and the increase in crosslink density markedly strengthened the three-dimensional network structure of hydrogels, and the tensile strength, compression and bending properties of the composite’s hydrogels were fine with the content of DMAEMA in a certain range. When the DMAEMA content increased to 6 g/g(cellulose), the mechanical strength decreased obviously. An increase in the DMAEMA content resulted in a faster initial swelling rate and higher equilibrium swelling ratio (ESR). Secondly, freezing in hydrogel formation was beneficial to formation of interpenetrating network structure, which can raise its initial swelling rate and higher ESR. Freeze–thaw had a certain destructive effect on the micropore structure. Thirdly, three-dimensional structure and the increase of DMAEMA content can also improve the pH and temperature response sensitivity of hydrogels. Thus, the mechanical, swelling and responsive properties of this hydrogel could be adjusted by the DMAEMA content and polymerization modes.

A Novel pH, Thermo, and Magnetic Responsive Hydrogel Nanocomposite Containing Nanogel for Anticancer Drug Delivery

Hydrogels, nanogels, and nanocomposites have attracted much attention as drug delivery systems during the past decades. In this work, a novel drug delivery system was synthesized by incorporation of nanogel into multi responsive hydrogel nanocomposite. At first, nanogel was prepared by copolymerization of N‑isopropylacrylamide (NIPAM) and (2-dimethylamino)ethyl methacrylate (DMA). Then it was embedded it into pH, thermo, and magnetic responsive hydrogel nanocomposite including graft copolymerization of poly(2-dimethylamino)ethyl methacrylate (PDMA) onto salep (PDMA-g-salep) and Fe3O4 nanoparticles (NPs). The synthesized samples were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and atomic force micrographs (AFM). The sensitivity of the synthesized sample to temperature, pH, and magnetic field was studied using the swelling experiments. The drug release ability of the sample was also investigated at different pH, temperatures, and magnetic field. Finally, different kinetic models were used to discuss about the mechanism of drug release from the prepared sample. Our results represented the high efficiency of this kind of hydrogel nanocomposite for applications in cancer therapy.

Reconfigurable assembly of charged polymer-modified Janus and non-Janus particles: from half-raspberries to colloidal clusters and chains.

Understanding the dynamic and reversible assembly of colloids and particles into complex constructs, inspired by natural phenomena, is of fundamental significance for the fabrication of multi-scale responsive and reconfigurable materials. In this work, we investigate the pH-triggered and reconfigurable assembly of structures composed of binary mixtures of oppositely charged polyacrylic acid (PAA)-modified non-Janus and poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)/poly(N-isopropylacrylamide) (PNIPAM)-modified Janus particles driven by electrostatic interactions. Three different target structures are visible both in dispersions and in dry state: half-raspberry structures, colloidal clusters and colloidal chains depending on the mass, numerical and particle size ratio. All formed structures are well-defined and stable in a certain pH range. Half-raspberry-like structures are obtained at pH 6 and numerical ratios NJP/PAA-HP of 1 : 500 (for 200-PAA-HP), 1 : 44 (for 450-PAA-HP) and 1 : 15 (for 650-PAA-HP), respectively, due to electrostatic interactions between the central JP and the excessive PAA-HP. Colloidal chains and cluster-like structures are generated at numerical ratios NJP/PAA-HP of 4 : 5 (for 200-PAA-HP), 4 : 3 (for 450-PAA-HP), and 4 : 1 (for 650-PAA-HP). Moreover, the smaller the size of a “connecting” PAA colloid, the larger is the average length of a colloidal chain. Depending on the particle size ratio SJP/PAA-HP, some of the observed structures can be disassembled on demand by changing the pH value either close to the IEP of the PDMAEMA (for half-raspberries) or PAA (for colloidal clusters and chains) and then reassembled into new stable structures many times. The obtained results open a pathway to pH-controlled reconfigurable assembly of a binary mixture composed of polymeric-modified non-Janus and Janus particles, which allow the reuse of particle building blocks.

Non-Viral Transfection of Human T Lymphocytes

The genetic modification of human T lymphocytes with established non-viral methods is inefficient. Linear polyethylenimine (l-PEI), one of the most popular non-viral transfection agents for mammalian cells in general, only achieves transfection rates in the single digit percentage range for these cells. Here, a well-defined 24-armed poly(2-dimethylamino) ethyl methacrylate (PDMAEMA) nanostar (number average of the molecular weight: 755 kDa, polydispersity: <1.21) synthesized via atom transfer radical polymerization (ATRP) from a silsesquioxane initiator core is proposed as alternative. The agent is used to prepare polyplexes with plasmid DNA (pDNA). Under optimal conditions these polyplexes reproducibly transfect >80% of the cells from a human T-cell leukemia cell line (Jurkat cells) at viabilities close to 90%. The agent also promotes pDNA uptake when simply added to a mixture of cells and pDNA. This constitutes a particular promising approach for efficient transient transfection at large scale. Finally, preliminary experiments were carried out with primary T cells from two different donors. Results were again significantly better than for l-PEI, although further research into the response of individual T cells to the transfection agent will be necessary, before either method can be used to routinely transfect primary T lymphocytes.

A step-wise self-assembly approach in preparation of multi-responsive poly(styrene-co-methyl methacrylate) nanoparticles containing spiropyran

HypothesisSurfactant-free emulsion polymerization has become favorable due to circumventing instability issues reasonably. Incorporation of an appropriate hydrophilic macroRAFT, could provide controlled in-situ self-assembly via copolymerization with hydrophobic monomers into polymer particles. So far, this approach has mostly been studied in dispersion systems and further studies are needed in emulsions. Beside the corresponding mechanistic studies, the prepared latex particles would potentially exhibit smart behaviors by choosing stimuli-responsive monomers. ExperimentsPoly(styrene-co-methyl methacrylate) latexes were prepared by utilizing pH-responsive polydimethylaminoethyl methacrylate as the hydrophilic segment through polymerization induced self-assembly (PISA). A systematic study on the effect of MMA amount, role of smart spiropyran ethylacrylate (SPEA) comonomer and the synthesized macroRAFT for inducing efficient assembly has been performed comparatively for the first time. FindingsSEM and DLS analyses showed the effect of MMA content on the obtaining of spherical particles with bimodal or monodisperse size distributions in both series of samples. Kinetic studies through conversion measurements along with GPC analysis revealed that the incorporation of MMA and SPEA strongly affected the efficiency of in-situ self-assembly, particle formation and RAFT-controllability on molecular weights. Ultimately, acido/basochromism, pH-responsivity and UV-responsivity of the prepared latexes were verified and the results showed their facile and fast multi-responsivity.

Polyelectrolyte brushes as efficient platform for synthesis of Cu and Pt bimetallic nanocrystals onto TiO2 nanowires

A Cu–Pt nanoparticle catalyst supported on TiO2 nanowires (NWs) was prepared through regenerative counterion exchange–reduction using polyelectrolyte brush as template. Cationic polydimethyl aminoethyl methacrylate brushes were grafted onto TiO2 NWs. Cu–Pt nanocrystals were produced by anionic counterions CuCl42− and PtCl62− bound with the polymer brush through in situ reduction with NaBH4 of high density and low polydispersity. The as‐prepared TiO2 NWs/polymer brush/Cu–Pt was characterized by Fourier transform infrared spectroscopy (FT‐IR spectrometry), X‐ray photoelectron spectroscopy, transmission electron microscopy, and UV–Vis adsorption spectrometry analyses. Results showed that the highly dispersed Cu and Pt nanoparticles were present on the surface of the TiO2 NWs/polymer brush. The resultant TiO2 NWs/polymer brush/Cu–Pt exhibited extremely high catalytic activity and reduced p‐nitrophenol at room temperature. Copyright © 2017 John Wiley & Sons, Ltd.

CO2-switchable behavior of chitosan-g-poly[(2-dimethylamino)ethyl methacrylate] as an emulsifier

Chitosan-g-poly[(2-dimethylamino)ethyl methacrylate] was investigated as a CO2-switchable emulsifier in this study. Poly(2-dimethylamino)ethyl methacrylate (PDMAEMA) was prepared by atom transfer radical polymerization followed by grafting to chitosan (CS). The CO2-responsiveness and reversible CO2-switchable temperature- and pH-sensitive behavior of PDMAEMA and CS-g-PDMAEMA were investigated as emulsifiers via simple CO2 and N2 bubbling. The lower critical solution temperatures (LCSTs) of PDMAEMA and CS-g-PDMAEMA aqueous solutions both increased as pH decreased to about pH 7.3, at which point the LCSTs disappeared. At elevated temperatures (e.g. 60°C), CO2 bubbling removed the turbidity in CS-g-PDMAEMA aqueous solution and N2 bubbling restored turbidity. The presence of CS-g-PDMAEMA in a two-phase solution of n-butanol/deionized water enabled the formation of a completely emulsified single phase after CO2 bubbling, which reverted to a two-phase solution on N2 bubbling. Overall, CS-g-PDMAEMA has potential as a CO2-switchable emulsifier.

Superparticles Formed by Amphiphilic Tadpole-like Single Chain Polymeric Nanoparticles and Their Application as an Ultrasonic Responsive Drug Carrier

Herein, we report self-assembly of tadpole-like single chain polymeric nanoparticles (TPPs) and the ultrasonic response of the resultant superparticles. The TPPs are with an intramolecularly crosslinked poly(2-(methacryloyloxy)ethyl pent-4-ynoate)-r-poly(hydroxyethyl methacrylate) (PMAEP-r-PHEMA) chain as the “head” and a poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA) linear chain as the “tail”, and are prepared simply and efficiently by Glaser-coupling of the pendant alkynes in the PMAEP-r-PHEMA block in the common solvent methanol. The formation of the TPPs was confirmed by gel permeation chromatograph, nuclear magnetic resonance spectroscopy, dynamic light scattering, static dynamic scattering, and transmission electron microscopy. In aqueous solution, the amphiphilic TPPs could self-assemble into regular superparticles, driven by aggregation of the hydrophobic “heads”. Since in the structure there is no chain entanglement and the embedding of PDMAEMA chains disturb close-packing of the “heads”, the superparticles are responsive to a low-energy ultrasonic vibration, as evidenced by greatly enhanced release of the functional molecules from the superparticles by treatment of a low-energy ultrasound. Therefore, the superparticles should be very promising in the use as the drug carriers that can be manipulated from a long distance, considering that ultrasonic energy can be focused at a small area in a relatively long distance from the ultrasound-radiating source.

Enhancing acid recovery efficiency by implementing oligomer ionic bridge in the membrane matrix

We report a strategy in improving the diffusion dialysis efficiency of anion exchange membranes (AEMs) by implementing a multi-amine oligomer bridge in the membrane matrix. The multi-amine oligomer, poly-dimethyl aminoethyl methacrylate (PD) was prepared via free radical polymerization, followed by partial quaternization with methyl iodide. The remaining tertiary amine groups were designed to react with benzyl bromide groups in the polymer brominated poly(2,6-dimethyl-1,4-phenylene oxide (BPPO) matrix, thus creating an intermolecular connection. The intermolecular connection serves as crosslinks and also helps to regulate the interconnectivity of the hydrophilic regions. By tuning the molecular weight and the remaining tertiary amine groups within PD, series of AEMs were fabricated. These membranes show potential in recovering waste acid via diffusion dialysis. For example, membrane M-5 shows an extraordinarily high separation factor (SH/Fe) of ∼2074 along with acceptable proton dialysis coefficient (UH=0.0098m/h). The SH/Fe is much higher than that of the conventional quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO) membrane without oligomer cross-linker (UH=0.0080–0.0132m/h,SH/Fe=5–60). The improvement in diffusion dialysis efficiency could be attributed to the improved interconnectivity of the hydrophilic regions, which stems from the incorporation of inter-chain ionic bridge.