N-dimethylaminoethyl Methacrylate Research Articles

Preparation of diblock copolymer nano-assemblies by ultrasonics assisted ethanol-phase polymerization-induced self-assembly

Assemblies are widely used in biomedicine, batteries, functional coatings, Pickering emulsifiers, hydrogels, and luminescent materials. Polymerization-induced self-assembly (PISA) is a method for efficiently preparing particles, mainly initiated thermally. However, thermally initiated PISA usually requires a significant amount of time and energy. Here, we demonstrate the preparation of nano-assemblies with controllable morphologies and size using ultrasound (20 kHz) assisted ethanol-phase RAFT-PISA in three hours. Using poly (N, N-dimethylaminoethyl methacrylate) as the macromolecular reversible addition-fragmentation chain transfer agent (PDMA-CTA) to control the nucleating monomer benzyl methacrylate (BzMA), we obtained nano-assemblies with different morphologies. With the length of hydrophobic PBzMA block growth, the morphologies of the assemblies at 15 wt% solid content changed from spheres to vesicles, and finally to lamellae; the morphologies of the assemblies at 30 wt% changed from spheres micelles to short worms, then vesicles, and finally to large compound vesicles. With the same targeted degree of polymerization, nano-assemblies having a 30 wt% solid content display a more evolved morphology. The input of ultrasonic energy makes the system have higher surface free energy, results the mass fraction interval of solventphilic blocks (fhydrophilic) corresponding to the formation of spherical micelles is expanded from fhydrophilic > 45 % to fhydrophilic > 31 % under ultrasound and the fhydrophilic required to form worms, vesicles, and large composite vesicles decreases in turn. It is worth noting that the fhydrophilic interval of worms prepared by ultrasonics assisted PISA gets larger. Overall, the highly green, externally-regulatable and fast method of ultrasonics assisted PISA can be extended to vastly different diblock copolymers, for a wide range of applications.

Antioxidant-rich brilliant polymeric nanocomposites for quick and efficient non-enzymatic hydrogen peroxide sensor.

In our current research, a new type of functional nanocomposites known as poly(methyl methacrylate/N,N-dimethyl aminoethylmethacrylate/(E)-2-cyano-N-cyclohexyl-3 (dimethylamino) acrylamide) [poly(MMA/DMAEMA/CHAA)] has been developed. These nanocomposites were created using microemulsion polymerization in conjunction with synthesized titanium dioxide (TiO2), and vanadium pentoxide (V2O5) nanoparticles. To understand the physio-chemical characteristics of the poly(MMA/DMAEMA/CHAA) and the metal oxide nanoparticles (MOs) integrated within them, various analytical techniques were employed. These techniques included Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and electrical approaches such as cyclic voltammetry (CV) and electrical impedance spectra (EIS). Based on the TEM results, nanospheres with a well-defined structure were developed for both the pure polymer and its composite with sizes ranging from 45 to 75 nm. All the TiO2 and V2O5-based nanocomposites showed significantly enhanced electrical attributes, with capacitance values surpassing those of the poly(MMA/DMAEMA/CHAA) nanosphere assemblies by a considerable margin. As a result, both direct electron transfer and direct hydrogen peroxide identification were evaluated for the nanocomposites. The amperometry results demonstrated a lower detection limit of 0.0085 μM and a rapid linear sensitivity in the range of 1 to 800 μM. The greatly improved electrolytic qualities of these nanocomposites make them suitable for various applications in fields such as battery storage, sensors, and biosensors.

In vitro DNA plasmid condensation and transfection through pH-responsive nanohydrogel.

Nanohydrogels (NHs) with the benefits of both nanomaterials and hydrogels unlock novel opportunities and applications in biomedicine. Nowadays, cationic NHs have attracted attention in the delivery of genetic materials into cells. Herein, by using reversible addition-fragmentation chain transfer method, an NH-based poly(hydroxyethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate) and cross-linked by poly(ethylene glycol)diacrylate with pH responsiveness character was developed. Several techniques including nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and gel permeation chromatography confirmed the success in the synthesis. The pH responsiveness of the developed NH was shown by transmission electron microscopy and dynamic light scattering technique. The average sizes of NHs in the normal (7.4) and acidic pH (5.5) were 180 and 390nm, respectively. The ability of the developed NH to condense genetic materials was checked using gel retardation assay with different ratios of NH and pCMV6-IRES-AcGFP, as a plasmid encoding green fluorescence protein. Results of gel retardation assay showed a decreasing trend in plasmid electrophoretic mobility with the increase in the NH concentration. The NH/plasmid complexes were stopped completely at the ratio of 5 and the plasmid band vanished at the ratio of 10. The quantitative and qualitative results of the cell transfection experiment using different ratios of NH/plasmid showed the ability of NH to carry plasmid molecules into the cancerous cells. The best transfection efficiency was observed by nanohydrogel/plasmid weight ratio of 10, while other ratios including 2, 5 and 20 showed 0.8, 10 and 12% of transfection efficiency, respectively. All the assessed factors showed that NH has the potential to be considered as an efficient gene delivery vehicle.

Development of Novel Antimicrobial Dental Composite Resin with Nano Cerium Oxide Fillers

Objectives To assess the antibacterial efficacy of experimental dental composite resin with cerium oxide nanoparticles as fillers. Methods The cerium oxide nanoparticles were prepared by the coprecipitation procedure. Synthesized 3wt% CeO2 nanoparticles were added to the composite resin as antibacterial filler. Experimental composite resin was manually prepared by adding ingredients. The resin matrix consisted of two mixed monomers, bisphenol A-glycidyl methacrylate and triethylene glycol dimethacrylate, diketone as the photo initiator, and N, N-dimethylaminoethyl methacrylate as a coinitiator. The antibacterial efficacy against Streptococcus mutans, Streptococcus mitis, Streptococcus aureus, and Lactobacillus spp. bacterial strains was tested using the microdilution method keeping commercially available 3M Filtek Z250 restorative composite as control. Results The experimental dental composite demonstrated 99.503% efficacy against Streptococcus mutans, 99.441% efficacy against Streptococcus mitis, 99.416% efficacy against Streptococcus aureus, and 99.233% efficacy against Lactobacillus spp. Conclusion Integrating cerium oxide nanoparticles as fillers into dental composite resin can be promising in terms of antibacterial activity, provided furthermore study has to be conducted to examine other properties. Clinical Significance. Previous studies attempted adding CeO2 nanoparticles into acrylic resins that showed improvement in mechanical properties, but literature is nil on the dental composite resin and cerium oxide nanoparticles. This study demonstrates the development of an experimental antibacterial dental composite resin that can resolve most of the problems related to secondary caries around dental composite restorations.

Thermo- and pH-responsive POEGMA-b-PDMAEMA-b-POEGMA triblock copolymers

A series of thermo- and pH-responsive triblock copolymers based on poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) and poly(N, N-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesised by RAFT polymerisation. The kinetics of the polymerisation of OEGMA and DMAEMA have been studied. The effect of the degree of polymerisation (DP) of the OEG side chain of the POEGMA block and the PDMAEMA block, temperature, pH, solvent, and concentration on the phase behaviour of the POEGxMAy-b-PDMAEMAz-b-POEGxMAy copolymers solutions were investigated comprehensively. At pH 5, the self-assembly of POEG5MA17-b-PDMAEMAz-b-POEG5MA17 copolymers induced by heating was driven by the POEG5MA dehydration, resulting in structures with hydrodynamic radii RH > 100 nm. On the other hand, at pH 9, 1H NMR studies showed that both blocks, PDMAEMA and POEG5MA, dehydrated with increasing temperature, forming stable aggregates with RH ≈ 20 nm, at a concentration of 0.125 mg mL−1. However, by increasing the concentration to 5 mg mL−1, these aggregates precipitated above 70 °C. The increase in the DP of the PDMAEMA block caused a decrease in the RH of aggregates at pH 7 and 9 at 25 °C. This effect was gradually attenuated by the increase in the DP of the OEG side chain and accompanied by an increase in the Tcp of the PDMAEMA block. Cryo-TEM images showed that the copolymers self-assembled as spherical and elongated micelles depending on their concentration and temperature. The copolymers were capable of Reichardt’s dye incorporation at pH 9, demonstrating the hydrophobic nature of the PDMAEMA core of the self-assembled structures.

Synthesis of tertiary amine functionalized Multi-Stimuli-Responsive latex nanoparticles by semicontinuous emulsion Polymerization: Investigation of responsivities and antimicrobial activity

Stimuli-responsive core–shell nanoparticles (CSNPs) are an important class of smart polymers, which their physical and chemical properties could be changed in response to induced external stimuli. In this study, the amphiphilic CSNPs were synthesized via semi-continuous seeded emulsion polymerization using dimethylamino ethyl methacrylate (DMAEMA) as a hydrophilic monomer, and styrene as a hydrophobic monomer. Developed CSNPs were obtained in two series, poly(N, N-dimethylamino ethyl methacrylate) (PDMAEMA)-polystyrene (PS) core–shell particles and PS-PDMAEMA core–shell particles. The PDMAEMA chains exhibited different responsivities towards temperature rising, pH change, and CO2-gas, which their smart behaviors were investigated by dynamic light scattering (DLS) analysis. The temperature-responsivity of CSNPs was confirmed by observed particle size variation in the case of PDMAEMA-PS (increase) and PS-PDMAEMA (decrease) core–shell latex particles, when temperature increased to 70 °C, above the lower critical solution temperature (LCST) of PDMAEMA. Protonation of tertiary amine functional groups in the presence of CO2 bubbling led to an increase in the size of CSNPs as a result of water swelling of PDMAEMA chains. On the other hand, the size of CSNPs was changed in acidic (pH = 4) and basic (pH = 10) media by swelling and deswelling of PDMAEMA located in the core or shell. Obtained results indicated that maximum antimicrobial activity was observed for PS-PDMAEMA CSNPs compared to PDMAEMA-PS, which is probably due to presence of the PDMAEMA on the surface and increase of positive charge related to amine groups in this sample. The developed antimicrobial latexes have potential applications for using as antibacterial additives in water-based coatings and adhesives.

Lignosulfonate/diblock copolymer polyion complexes with aggregation-enhanced and pH-switchable fluorescence for information storage and encryption

Employing natural polymers as building blocks is favorable to construct sustainable functional materials and realize biomass utilization. Here we developed a series of supramolecular polyion complexes (PICs) composed of lignosulfonate and double-hydrophilic diblock copolymer poly(ethylene oxide-b-N, N-dimethylaminoethyl methacrylate) (PEO114-b-PDMAEMA24), which performed a blue emission with quenching-enhancing tendency and copolymer distribution inversion-involved assembling transformation at pH 5.6 and monotonic greenish-blue fluorescence promotion at pH 9.5 by increasing PEO114-b-PDMAEMA24 contents. Electrostatic interactions and multiple hydrogen bonds were revealed controlled the assembling behavior and affected the emission via altering the restriction of molecular motion, through-space conjunction, and non-luminous complexation. The multiple interacting sites and special topology of diblock copolymer contributed to the efficient fluorescence regulation. Information writing-erasing and encryption-decryption systems were established by utilizing emission intensity regulation and pH-responsive emission chromism. This work paved a new way to enhance lignin fluorescence and broadened potential applications of lignin composites in realms of sensing, imaging, monitoring, and anticounterfeiting.

Physical and Mechanical Properties of Films Based on Graft Copolymers of Chitosan with N, N-Dimethylaminoethyl Methacrylate

The graft-polymerization of N, N-dimethylaminoethylmethacrylate (DMAEMA) on chitosan (CTS) was performed in the presence of ammonium persulfate (PSA) at a temperature of 323K. The effect of the DMAEM concentration in the reaction mixture on the copolymer yield, the degree and effectiveness of grafting, as well as on the physical-mechanical properties of films obtained on the basis of synthesized copolymers was studied. The copolymers formation was prooven by gravimetric method, extraction, and IR spectroscopy. Chitosan-graft-DMAEM copolymers of various compositions were obtained. The grafing degree reached ~ 350 wt. % with the ratio [DMAEMA]/[CTS] = 5 (mol/(base-mol), the grafting effectiveness was ~ 86 wt. % with the ratio [DMAEMA]/[CTS] = 1 (mol/(base-mol). It was established that the changing the copolymers composition lead to variation of tencile strength and deformation characteristics of films widely from 1.4 MPa to 25.7 MPa and from 34% to 413%, correspondingly.

Radiation development of gastroretentive amoxicillin trihydrate floating-alginate based beads for the treatment of helicobacter pylori

Development of controlled drug release carriers with gastroretentive ability is one of the most feasible approaches to improve the bioavailability and efficiency of medical treatment of Helicobacter pylori-induced peptic ulcers. Consequently, modification of alginate with N, N-dimethylamino ethyl methacrylate was occurred via graft copolymerization technique using γ-irradiation. (Alg-g-DMAEMA) copolymers were used to prepare Amoxicillin-Trihydrate floated hollow beads using calcium chloride as crosslinker and calcium carbonate as a gas-forming agent to induce floatability. Swelling behavior, floatability, and gastric retention time were investigated in simulated gastric fluid. Morphological features, drug encapsulation efficiency, and in vitro (AT) release were evaluated. Beads show internal hollow construction with bulk density ranged from 0.393 to 1.533 (g/cm3) and enhanced gastric residence time extended up to 24 h. Drug entrapment efficiency ranged between 63 to 97% with sustainable release behavior extending beyond 15 h depends on beads p (DMAEMA) content. The newly developed pH-sensitive floated (AT) loaded (Alg-g-DMAEMA) beads are promising for increasing gastric residence time with sustained (AT) release which improves its bioavailability for the effective treatment of H. pylori. The in-vitro study showed that (AT) loaded beads eradicate more than 95% of H. pylori after 10 h.

Understanding the role of water in the aggregation of proteins and polymers in aqueous solution using near-infrared spectroscopy

Water plays an important role in chemical and biological processes. For understanding the role of water in the aggregation of proteins and polymers, the variation of water structures in the process of aggregation was studied by near-infrared spectroscopy. The near-infrared spectra of the aqueous R2/wt and poly( N, N-dimethylaminoethyl methacrylate) solutions of different concentrations were measured at different temperatures. The spectral changes of the solutes and water with temperature were analyzed with the help of chemometric methods. In the aggregation of R2/wt, the water species with one hydrogen bond around the NH groups dissociate to initiate the change of the hydrogen bonding network of the hydration water, and then, the water molecules with two hydrogen bonds (S2) near the hydrophobic side chains release from the R2/wt, resulting in the formation of the ordered amyloid fibers. In the aggregation process of low concentration poly( N, N-dimethylaminoethyl methacrylate) solutions, the chains of the polymer tend to form a loose hydrophobic structure below 36°C and then aggregate into a micelle at a lower critical solution temperature of around 39°C. S2 acts as a bridge to connect the polymer chains in the loose hydrophobic structure, and the dissociation of the S2 bridge at high temperature is the reason for the formation of the micelle. For high concentration solution, however, the spectral information of S2 was not found in the aggregation, suggesting a direct formation of the micelle from the dehydrated chains.

Preparation and characterization of Novel Bis-GMA Dental Nanocomposite and their application as dental material: Mechanical Properties and Water Sorption/volumetric shrinkage

Novel Nanocomposite materials on the basis of unsaturated monomers as well as 2,2 propyl bisphenol glycidyl dimethacrylate (Bis-GMA) and unsaturated monomers with Nano inorganic fillers [SiO2, ZrO2 and Hydroxyapatite (HA)] were subjected to process of synthesizing as well as characterizing for the purpose of evaluating their possible applications as restorative materials in the field of dentistry. The initial method has been for generating in addition to characterizing novel Nanocomposites bases on (Bis-GMA), N,N′-methylene bis acryl amide (MBA), acrylic acid(AA) and methylacrylate(MA) monomers. Composites containing Bis-GMA and N,N′-methylene bis acrylamide (MBA) with the ratio (wt/wt) of (40/20), which has been filled with various Nanofiller amounts (up to 5% wt) were prepared. Photo-polymerization has been induced with camphorquinone/N,N-Dimethylaminoethyl methacrylate(CQ/DMAEMA), as photo-initiator system. Physicochemical properties, such as solubility (SL), water sorption (WS), as well as the volumetric shrinkage (VS) have been examined. The mechanical properties of the of dental Nanocomposites flexural strength and compressivewere widely discussed. Characterization will be implemented through the use of FTIR and SEM are applied for showing particle size distribution in addition to particle agglomeration related to the treated Nanofillers in Nano-composites. FTIR spectroscopy has been initially applied for identifying qualitative composition of composition of Nanocomposites. The Thermal stability of all dental Nanocomposites were also studied using the TGA and DSC techniques.

Adsorption and release of caffeine from smart PVDF polyampholyte membrane

pH sensitivity, load, and release of caffeine from polyampholyte, acrylic acid (AAc), and 2-N,N-dimethylamino ethyl methacrylate (DMAEMA) grafted onto DURAPORE® PVDF membrane were studied. Polyampholyte was previously “grafted-from” on membranes by gamma irradiation technique in two steps: (1) PVDF-g-DMAEMA using direct method and (2) grafted AAc by pre-irradiation method, to obtain (PVDF-g-DMAEMA)-g-AAc. The results showed that binary copolymer grafted onto PVDF membrane PVDF-g-DMAEMA-g-AAc acts as responsive porous polymer membrane to control drug delivery. For this project, caffeine was used as a model drug. Drug adsorption was enhanced by the dissociation of grafting chains (PAAc and PDMAEMA) and by drug charge. The adsorption results showed that caffeine was loaded and released by the modified membrane and due to the nature of binary copolymer and the drug adsorption. Additional analysis as mechanical testing, scanning electron microscopy, and contact angle measurements was done to characterize the polyampholyte. This work designates the role of pH-sensitive acid, alkaline, and polyampholyte monomers in the improvement of no functionalized fluoropolymer membranes imparting its pH sensitivity and specific interaction with charged molecules as some drugs, proteins, or metals among others. The present results show that the load and release of caffeine adsorbed onto the pH-sensitive membrane and its strong dependence on pH and grafting degree. The membrane may be suitable for separating drugs from protein aqueous substances for subsequent monitoring and evaluation process.

Scalable and rapid preparation of Janus fabric by trans-printing method for efficient oil/water emulsion separation

The old-fashioned yet effective trans-printing method was adopted to prepare Janus fabric in the study. Nonwoven cotton fabric was firstly immersed in tetrahydrofuran solution containing P(DMAEMA-co-TMSPMA), a polymer synthesized by copolymerization between N, N-dimethylaminoethyl methacrylate (DMAEMA) and 3-(trimethoxysilyl)propylmethacrylate (TMSPMA), followed by thermal treatment, thus endowing the fabric with the demulsification property. Next, one side of the above prepared fabric was overlapped and rolled with donor fabric containing PDMS-g-TMOS, a polymer synthesized by thiol/ene click reaction between multi-vinyl poly(dimethylsiloxane) (vinyl-PDMS) and 3-mercaptopropyltrimethoxysilane (MPTMOS). The PDMS-g-TMOS polymer infiltrated into the fabric cured with P(DMAEMA-co-TMSPMA) to a certain depth, followed by thermal treatment. Thus, the resultant fabric had both the superhyrophilic side for oil coalescence and the superhyrophobic side for oil permeation. The Janus fabric structure was confirmed by metalloscope, unidirectional water transport property (UDWT), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). When the prepared fabric was used to separate model oil hexadecane (HD) from oil-in-water emulsion, the maximum separation speed was 134.5 kg h−1 m−2. The recovery rate of HD respectively reached 96.0% after 60 min and 99.9% after 150 min. The Janus fabric prepared by the trans-printing method is particularly suitable for industrial production and of great industrial value.

Grafting antibacterial polymer brushes from titanium surface via polydopamine chemistry and activators regenerated by electron transfer ATRP

An environmentally benign and convenient approach to impart titanium (Ti) surfaces with antibacterial functionalities was described in this work. Polydopamine (PDA) was first deposited onto an alkali activated Ti substrates. Then 2-bromoisobutyryl bromide (BIBB) was immobilized on the surface of PDA coated Ti. Finally, the BIBB functionalized Ti initiated the polymerization of N, N-diethylaminoethyl methacrylate (DEAEMA) and N, N-dimethylaminoethyl methacrylate (DMAEMA) to obtain Ti@PDA-g-polymer brushes by activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP). The prepared PDEAEMA and PDMAEMA brushes on Ti surfaces would be subsequently quaternized by using 1-bromooctane, which would impart the obtained products with quaternary ammonium groups. The surface compositions of the functionalized Ti were characterized by X-ray photoelectron spectroscopy (XPS). The hydrophilic/hydrophobic properties of the functionalized Ti surfaces were determined by static water contact angle measurements, and morphologies were characterized by scanning electron microscope (SEM). Antibacterial abilities of quaternized PDEAEMA and PDMAEMA coated Ti were evaluated by the contact killing test, in which live/dead cell staining method was employed. The results showed that the quaternized polymer decorated Ti exhibited good bactericidal effects against Escherichi coli (E. coli), and its inhibition rate of E. coli were observed to be nearly 90%.

NIR-Light- and pH-Responsive Graphene Oxide Hybrid Cyclodextrin-Based Supramolecular Hydrogels.

Here, a novel triple-responsive graphene oxide hybrid supramolecular hydrogel based on the electrostatic self-assembly between graphene oxide and a quaternized polymer and the host-guest inclusion between α-cyclodextrins and poly(ethylene glycol) monomethyl ether (mPEG) was constructed. The quaternized polymer was synthesized by quaternization between pH-sensitive poly( N, N-dimethylaminoethyl methacrylate) and bromine end-capped poly(ethylene glycol) monomethyl ether. The supramolecular hydrogels prepared from the host-guest inclusion of poly(ethylene glycol) monomethyl ether and α-cyclodextrins would turn into a mobile sol phase when the temperature was increased above a certain temperature (Tgel-sol). Graphene oxide sheets not only acted as a core material to provide additional cross-linking but also absorbed NIR light and converted NIR light into heat to trigger the gel-sol transition. The constructed graphene oxide hybrid cyclodextrin-based supramolecular hydrogels could respond to NIR light, temperature, and pH, which could be beneficial for controlled release of cargoes and would hold great promise in the field of delivery systems.

Smart pH responsive drug delivery system based on poly(HEMA-co-DMAEMA) nanohydrogel

The advent of smart nanohydrogel has revealed new opportunities for scientists to develop the most efficient anti-cancer vehicles with safe and biocompatible profile. In this experiment, using reversible addition-fragmentation chain transfer polymerization method as a novel, safe and smart pH responsive formulation of poly (hydroxyethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate) and poly (ethylene glycol)-diacrylate as cross-linker were synthesized. The synthesized structure was confirmed by Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance methods. The pH responsive behavior of the synthesized particles was checked by size measurement in two different pH values (5.5 and 7.4) by dynamic light scattering and transmission electron microscopy. The prepared structure had nanometer sizes of 180 in medium with pH of 7.4, when it encountered acidic medium (e.g. pH 5.5), the particles swelled to about 400 nm. The efficiency of the prepared pH responsive nanohydrogels was tested as a drug delivery system. An anti-cancer drug, doxorubicin successfully interacted with this material. The release profiles of nanoparticles carrying drug molecules were checked in two different simulated pH of healthy organs (7.4) and tumor site (5.5). Despite lower release in pH of 7.4 (∼20%), an increased drug release of 80% was obtained in pH of 5.5. The in vitro toxicity assay, apoptosis evaluation and uptake experiments were performed on breast cancer cell line (MCF-7), which showed a time dependency cellular entrance, an enhanced cytotoxicity and apoptosis induction by the doxorubicin loaded nanoparticles. Hemolysis assays confirmed the safety and hemocompatibility of the developed nanohydrogel. The suitable size (<200 nm), pH responsive behavior, anti-proliferative activity and apoptosis induction in cancer cells and hemocompatibility were the noticeable features of the developed doxorubicin adsorbed nanoparticle, which introduced this formulation as an ideal vehicle in anti-cancer drug delivery.

Photo-crosslinked mechanically strong PCL4-PDMAEM hydrogels

In this study, a series of thermo-responsive hydrogels based on N′N-dimethylaminoethyl methacrylate (DMAEM) and methacrylate functionalized poly(caprolactone) (PCL4-IEMA) were prepared by bulk photo-polymerization method. Poly(caprolactone) (PCL) was modified with 2-isocyanatoethylmethacrylate (IEMA) to form a macro-crosslinker due to its excellent biocompatibility to generate high-strength smart hydrogels with pH and temperature responsivity. The synthesized macro-crosslinker and PCL4-PDMAEM hydrogel were characterized by 1H NMR, GPC and FT-IR analyses. Sol-gel transitions were examined by oscillatory measurements in Rheometer under UV light. Swelling kinetics as a function of time, swelling ratios at different pH values and temperatures were studied. pH responsive swelling behavior of PCL4-PDMEAM hydrogels was demonstrated with a highest swelling value at pH = 2. Temperature responsivity was also proved with a LCST around 40 °C between the shrunken and swollen state. Young modulus of the sample was also calculated around 0.3 MPa. The results indicated that using PCL4-IEMA as a macro-crosslinker is an effective way to obtain mechanically strong - tough - hydrogels by means of dissipating the applied energy through flexible crosslink units. In addition, swelling and mechanical properties of the hydrogels could be tailored by varying the amount of the crosslinker.

Tailoring the physico-chemical properties and elasticity of poly(hydroxy-functional methacrylate)-based cationically charged gel beads: Combined hydrophobicity and mechanical durability through frozen droplets

This study describes the experimental methodology to obtain hydroxy-functional methacrylate-based gel beads in millimeter-sized under production conditions by addition of the frozen pre-gel solution into the silicon oil as continuous phase using tetraethyleneglycol dimethacrylate (TEGDMA) as the crosslinking agent. Weakly basic cationic comonomer N,N-dimethylaminoethyl methacrylate (DMAEMA) was included into the polymerization procedure for the production of uniform polycationic moities exhibiting a drastic response against pH. The aim of this work is to determine the actual conditions for optimum bead production and to provide poly(hydroxypropyl methacrylate-co-N,N-dimethylaminoethyl methacrylate)-based P(HPMA-co-DMAEMA) gel beads with simple tools for the physical characterization. By the proposed experimental method, the physico-chemical properties of P(HPMA-co-DMAEMA) gel beads can be controlled by adjusting the pH, temperature of solution, ionic strength as well as the structure of the gel network. From the uniaxial compression tests, the swelling dependent stress–strain characteristics of resulting gel beads was evaluated. The obtained results were consistent with Hertzian elasticity, and were analyzed in terms of the compression modulus of the bead samples. It was found that force acting on the gel beads is the power-law function of the deformation F≈ΔD1.48 which is very close to the theoretical exponent 1.5 predicted by the Hertz equation. The water absorption capacities of P(HPMA-co-DMAEMA) gel beads with basic functional groups were repeatedly measured to obtain the optimal preparation conditions according to the variations of the bead diameters. Its maximal water absorption capacity appeared as 48 times among from 2.3mm to 11.0mm of swollen bead diameters. The swelling equilibria in various aqueous solutions were used to estimate the physico-chemical parameters asa function of gel bead size and swelling equilibrium capacity by correlating with the Flory-Rehner theory.

Preparation and characterization of poly(N-isoproylacrylamide-co-dimethylaminoethyl methacrylate) microgels and their composites of gold nanoparticles

This work reports the crosslinkage of N-Isopropylacrylamide (NIPAM) and N, N-dimethylaminoethyl methacrylate (DMAEMA) in water using N, N’- methylene-bis(acrylamide) (BIS) as crosslinker. The particle size, volume phase transition temperature (VPTT), swelling and deswelling behaviors of the obtained poly(NIPAM-co-DMAEMA) microgels were studied at different temperature and pH using dynamic light scattering (DLS) technique. Additionally, investigation of particle size and VPTT of the microgels was done by altering the content ratio of DMAEMA monomer. The prepared microgels were used as a nanoreactor for the synthesis of gold nanoparticles (Au-NPs) using sodium borohydride (NaBH4) as reducing agent. The in situ synthesized Au-NPs were characterized and visualized by UV–vis Spectroscopy and TEM analysis, respectively. Optical properties of poly(NIPAM-co-DMAEMA)/Au-NPs composite were studied by changing the concentration of gold(III) chloride trihydrate (HAuCl4·3H2O), sodium borohydride (NaBH4) and temperature of the system. The prepared microgel composite were used as a catalyst for the reduction of toxic 4-nitrophenol (4-NP) with apparent rate constant (kapp) of 0.336min−1. Catalytic activities of the microgel composite were tuned by making use of thermoresponsive behavior of the microgels. Due to temperature and pH responsive nature of the synthesized microgels they have potential for application in drug delivery and sensory materials.

Synthesis, characterization and thermal properties of the nano four arms poly(pentaerythritollactide-b-N,N-dimethylaminoethyl methacrylate) derivatives

The nano four arms poly(lactide- b - N,N -dimethylaminoethylmethacrylate) were prepared by pentaerythritol-lactide atom transfer radical polymerization initiators having different repeating units (10, 25, 50 and 100) of L-lactide with the same amount of N , N -dimethylaminoethyl methacrylate by atom transfer radical polymerization reaction. The copolymers were characterized FT-IR, 1 H NMR, 13 C NMR and Gel permeation chromatography. These characterization methods confirmed the structures of prepared copolymers. Scanning electron microscopy, on the other hand, revealed that the presence of a nanostructure in the prepared copolymers attributed to the lactide fibers. Then, the thermal study was carried out on the copolymers the results have proven to increase the thermal stability of the copolymers with the increasing chain length of the lactide.