Hemostatic Sponge Based on Modified Alginate and Water-Soluble Chitosan for Rapid Hemorrhage Control.

Synthesis of densely grafted copolymers with tert-butyl methacrylate/2-(dimethylamino ethyl) methacrylate side chains as precursors for brush polyelectrolytes and polyampholytes

Structure investigation of poly((2-dimethylamino)ethyl methacrylate)/sodium dodecylsulfate complexes in concentrated poly((2-dimethylamino)ethyl methacrylate) solutions using small angle neutron scattering

Three different ratios of double hydrophilic block copolymers poly [2-(dimethylamino) ethyl methacrylate]-b-poly(oligo(ethylene oxide) monomethyl ether methacrylate)-b-poly [2-(dimethylamino) ethyl methacrylate] (PDMAEMA-b-POEOMA-b-PDMAEMA) were synthesized by reversible addition fragmentation chain-transfer polymerization (RAFT), which was one of the controlled/living radical polymerization. The chain structure and component of such copolymers were characterized by spectroscopic studies (FTIR, 1H NMR). The interaction of PDMAEMA-b-POEOMA-b-PDMAEMA copolymers with copper sulfate and copper chloride solution was studied. It was found that the anion SO42-, Cl-1 could have an effect on the structure and coordination of the Cu(II) complexes, which were confirmed by FTIR and scanning electron micrographs (SEM).

Zwitterionic block copolymers can form polyion complex (PIC) micelles without any additional ionic compounds because their backbones contain both cationic and anionic residues. For the generation of polyion complex (PIC) micelles with tunable isoelectric points (pI), the zwitterionic block copolymers, poly(ethylene oxide)45-b-[poly(2-succinyloxyethyl methacrylate)x-r-poly(2-(dimethylamino)ethyl methacrylate)y] (PEO45-b-(PSEMAx-r-PDMAy)) zwitterionic block copolymers were synthesized via atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) and 2-(dimethylamino)ethyl methacrylate (DMA), and subsequent succinylation of the hydroxy groups on HEMA. The electrostatic interaction between oppositely charged 2-succinyloxyethyl methacrylate (SEMA) and DMA residues led to spontaneous micelle formation of the zwitterionic block copolymers in an aqueous solution. The pH-dependent protonation/deprotonation behavior of the SEMA and DMA residues induced a change in the net charge of the micelle. Since the pIs of PIC micelles are closely related to the SEMA to DMA ratio (x/y) of the zwitterionic block, PIC micelles with certain pI values, which can be predicted by simple calculations based on the average pKa values of DMA and SEMA, can be easily tailored to achieve our objectives. Open image in new window

In this paper, polyvinyl acetates (PVAcs) were prepared by free radical emulsion polymerisation at room temperature in the presence of persulphate and commercially available reducing agent monomer of 2-(dimethyl amino)ethyl methacrylate (DMAEMA). The molecular weight and the radius of gyration of the PVAcs were analysed by using gel permeation chromatography and dynamic/static light scattering，the storage modulus in a wide and high-frequency range of PVAcs microrheological properties was studied by the diffusive wave spectroscopy (DWS). By adjusting the concentration of persulphate and DMAEMA, Cole-Cole plots were used to demonstrate that a series of branched PVAcs with different branching degree were obtained. The increase of the DMAEMA concentration led to a higher degree of branching, the branched PVAcs showed low storage modulus and lower chain entanglement. The method can synthesise branched polymers through emulsion polymerisation at room temperature, enriching the synthesis of vinyl branched polymers，and offer a promising future for preparing branched vinyl polymers on a large scale and at low cost.

A natural polymer-based porous sponge with capillary-mimicking microchannels for rapid hemostasis

Polyethylene (PE) plates grafted with a neutral hydrophilic monomer, methacrylamide (MAAm), and a cationic monomer, 2-(dimethylamino)ethyl methacrylate (DMAEMA), (PE-g-PMAAm)-g-PDMAEMA plates, were prepared by the two-step photografting. The Cr(VI) ion adsorption of the resultant (PE-g-PMAAm)-g-PDMAEMA plates was investigated as a function of the initial pH value, temperature, and grafted amounts of PMAAm and PDMAEMA. The adsorption capacity of the (PE-g-PMAAm)-g-PDMAEMA plates had the maximum at the initial pH value of 3.0 and the initial adsorption rate increased with the temperature and increased with the amount of grafted DMAEMA. This result suggests that protonated dimethylamino groups present in the inside of the grafted layer are increasingly involved in the Cr(VI) ion adsorption by the increase in the water absorptivity through the formation of the intermediate grafted layer of PMAAm. The maximum adsorption ratio of 0.510 was obtained for a (PE-g-PMAAm)-g-PDMAEMA plate with G MAAm = 30 μmol/cm2 and G DMAEMA = 1.7 μmol/cm2. The maximum adsorption capacity obtained in this study was comparable to or higher than those of other adsorbents for Cr(VI) ions. The adsorption behaviour obeyed the pseudo-second order kinetic model and was well described by the Langmuir isotherm model, suggesting that the adsorption of Cr(VI) ions occurs through the electrostatic interaction between protonated dimethylamino groups and ions. Cr(VI) ions were successfully desorbed in such eluents as NaCl, NaCl containing NaOH, NH4Cl, NH4Cl containing NaOH, and NaOH and (PE-g-PMAAm)-g-PDMAEMA plates were repeatedly used without considerable loss in the adsorption capacity.

Synthesis of ‘living’ poly(2-dimethylaminoethyl methacrylate) and stimuli responsive/multifunctional block copolymers effective in fabrication of CdS ‘smart’ ‘Q-Particles’

A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP). A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE). Then l-poly(EO-co-EEGE) was cyclized. The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD. The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide, and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA), and a series of pH- and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained. The behavior of pH- and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS). The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured. Under the same conditions, the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value. The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA. The average hydrodynamic diameters (D h) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.

ABSTRACTPolyethylene (PE) plates grafted with a neutral monomer, 2-hydroxyethyl methacrylate (HEMA), and a cationic monomer, 2-(dimethylamino)ethyl methacrylate (DMAEMA), (PE-g-PHEMA)-g-PDMAEMA plates were prepared by the two-step photografting. The Cr(VI) ion adsorption behavior of the (PE-g-PHEMA)-g-PDMAEMA plates was investigated as a function of the amounts of grafted HEMA, amount of grafted DMAEMA, initial pH value, and temperature. The adsorption capacity of the DMAEMA-grafted PE (PE-g-PDMAEMA) and (PE-g-PHEMA)-g-PDMAEMA plates had the maximum value at the initial pH value of 3.0, independent of the temperature. The adsorption capacity of (PE-g-PHEMA)-g-PDMAEMA plates increased with the amount of grafted HEMA (GHEMA) in the first-step grafting. The increase in the water absorptivity of the grafted layers and thereby the increase in the degree of protonation of dimethylamino groups on grafted PDMAEMA chains were found to lead to the increase in the adsorption capacity. This adsorption capacity was higher than or comparable to those of other polymeric adsorbents for Cr(VI) ions. The Cr(VI) ion adsorption behavior on both PE-g-DMAEMA and (PE-g-PHEMA)-g-PDMAEMA plates obeyed the mechanism of the pseudo-second-order kinetic model and was well expressed by Langmuir isotherm. The high values of the Langmuir constant suggest that the adsorption of Cr(VI) ions occurs through an electrostatic interaction between protonated dimethylamino groups on grafted PDMAEMA chains and ions. Cr(VI) ions were successfully desorbed from PE-g-PDMAEMA and (PE-g-PHEMA)-g-PDMAEMA plates in eluents such as NaCl, NaCl containing NaOH, NH4Cl, NH4Cl containing NaOH, and NaOH.

A new methacrylate monomer 4-fluorobenzyl methacrylate (FBM) was synthesized and its radical copolymerization with 2-(dimethylamino)ethyl methacrylate (DMAEMA) was studied in 1,4-dioxane solution at 65°C using 2,2′-azobisisobutyronitrile as an initiator. The synthesized monomer and copolymers were characterized by FTIR, 1H and 13C NMR spectroscopy. The analysis of reactivity ratios revealed that FBM is less reactive than DMAEMA, and copolymers formed are statistically in nature. Thermogravimetric analysis of the polymers reveals that the thermal stability of the copolymers increases with an increasing in the mole fraction of FBM in the copolymers. Glass transition temperatures of the copolymers decreased with an increasing in the mole fraction of FBM in the copolymers. The polymers exhibit the semiconducting behavior, and the electrical conductivity increases with increasing both of the temperature and DMAEMA content in copolymer.

The physicochemical and rheological properties of a water-soluble chitosan (WSC) derivative were characterized in order to facilitate its use as a novel material for biomedical applications. The WSC was prepared by conjugating glycidyltrimethylammonium chloride (GTMAC) onto chitosan chains. Varying the molar ratio of GTMAC to chitosan from 3:1 to 6:1 produced WSCs with a degree of substitution (DS) that ranged from 56% to 74%. The WSC with the highest DS was soluble in water up to concentrations of 25 g/dL at room temperature. An increase in the polymer concentration gradually increased both the pH and conductivity of the WSC solutions. The rheological properties of the WSC solutions were found to be dependent on the salt and polymer concentrations as well as the DS value. In the absence of salt, the rheological behavior of the WSC was found to be typical of that for a polyelectrolyte in the dilute solution regime. However, the addition of salt decreased the viscosity of the polymer solution due to the reduction of electrostatic repulsions by the positively charged trimethylated ammonium groups of the WSC. In the concentrated regime, the viscosity of the WSCs was found to follow a power-law expression. The lowest DS WSC had the more favorable viscoelastic properties that were attributed to its high molecular weight, as confirmed by the stress relaxation spectra and intrinsic viscosity measurements. The effect of DS on the degree of interaction between WSC and the lipid egg phosphatidylcholine was investigated by FTIR analysis. Overall, the lower DS WSC had enhanced rheological properties and was capable of engaging in stronger intermolecular physical interactions.

Recently, numerous scientific articles related to water soluble chitosan (WSC) have been released. Since the solubility of chitosan is restricted to acidic media, and there is an increasing demand against to the derivative of the chitosan polymer, which is mainly to obtain a material both having solubility in aqueous media and also being chitosan property. One of the benefits of synthesis of water soluble chitosan is to obtain a water soluble polymer is easily miscible with a variety of compounds in aqueous solutions. In this review, water soluble chitosan derivatives are principally examined in terms of their biological and other applications. Biological activities of WSC derivatives are analyzed in the sense of antioxidant, antimicrobial and anticancer activity, respectively. Thereby, the collected data may be useful to compare novel synthesized water soluble chitosan derivatives with alternative structures.

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.

The hydrolytic stability of poly(2-(dimethylamino)ethyl methacrylate) was investigated and compared with the stability of its monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA), with 2-(dimethylamino)ethyl isobutyrate (DMAEIB), representing the repeating unit in the polymer, and with the related 3-(dimethylamino)propyl methacrylate (DMAPMA) (H0/pH range −0.5 to +12, at 37 °C, in aqueous solution). At pH < 3, the unsaturated DMAEMA and DMAPMA were more stable than the saturated DMAEIB. At pH 4−8, DMAEMA and DMAEIB were equally stable, but less stable than DMAPMA. This has been ascribed to a coordination of the protonated dimethylamino group and the ester carbonyl, rendering the ester more susceptible to nucleophilic attack of a hydroxyl ion. At alkaline pH (>pKa) no differences in stability between the compounds were found. P(DMAEMA), either in its free form or complexed to DNA, was substantially more stable to hydrolytic degradation than DMAEMA and DMAEIB. Fluorescence measurements performed with a copolymer of DMAEMA and dansyl ethyl methacrylamide showed that the dielectric constant (εr) experienced in the environment of the polymer backbone, was low (about 7). This microenvironment might be the reason for the hydrolytic stability of the polymer, since the hydrolysis of the monomer decreased substantially with decreasing εr of the medium. Accelerated degradation (80 °C, pH 1 and 7) of p(DMAEMA) and poly(2-(dimethylamino)ethyl acrylate), p(DMAEA), showed that p(DMAEA) was more sensitive to hydrolysis. This can be explained by the assumption that, due to the lack of the methyl group, the εr in the environment of the acrylate backbone is higher than the εr in the environment of the p(DMAEMA) backbone.