pH and salt responsive poly(N,N-dimethylaminoethyl methacrylate) cylindrical brushes and their quaternized derivatives

We present the synthesis and characterization of poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) cylindrical brushes, their pH responsiveness, and the corresponding quaternized analog, poly{[2-(methacryloyloxy)ethyl] trimethylammonium iodide} (PMETAI) brushes. PDMAEMA brushes were prepared by atom transfer radical polymerization (ATRP) using the grafting-from strategy. Initiating efficiencies of the ATRP processes were determined by cleaving the side-chains and gel permeation chromatography (GPC) analysis. Due to the slow initiation and steric hindrance, the initiating efficiency is only around 50%. The PDMAEMA brushes show worm-like structures and pH responsiveness, as proven by dynamic light scattering (DLS), atomic force microscopy (AFM), and cryogenic transmission electron microscopy (cryo-TEM) measurements. Strong cationic polyelectrolyte PMETAI brushes were produced by quaternization of the PDMAEMA brushes. AFM and cryo-TEM images showed similar worm-like morphologies for the PMETAI brushes. The PMETAI brushes collapsed in solution with high concentration of monovalent salt, as proven by DLS and AFM results.     

Polymer brush coatings for combating marine biofouling

A variety of functional polymer brushes and coatings have been developed for combating marine biofouling and biocorrosion with much less environmental impact than traditional biocides. This review summarizes recent developments in marine antifouling polymer brushes and coatings that are tethered to material surfaces and do not actively release biocides. Polymer brush coatings have been designed to inhibit molecular fouling, microfouling and macrofouling through incorporation or inclusion of multiple functionalities. Hydrophilic polymers, such as poly(ethylene glycol), hydrogels, zwitterionic polymers and polysaccharides, resist attachment of marine organisms effectively due to extensive hydration. Fouling release polymer coatings, based on fluoropolymers and poly(dimethylsiloxane) elastomers, minimize adhesion between marine organisms and material surfaces, leading to easy removal of biofoulants. Polycationic coatings are effective in reducing marine biofouling partly because of their good bactericidal properties. Recent advances in controlled radical polymerization and click chemistry have also allowed better molecular design and engineering of multifunctional brush coatings for improved antifouling efficacies.     

PDMAEMA/PSF中空纤维外压纳滤膜对无机盐的截留性能研究

主要研究聚甲基丙烯酸N,N-二甲氨基乙酯（PDMAEMA）/聚砜（PSF）中空纤维外压纳滤膜对不同种类无机盐的截留性能,并研究了无机盐溶液的浓度、运行压力、溶液温度、pH对截留性能的影响.实验表明：PD-MAEMA/PSF中空纤维纳滤膜荷正电,对离子的截留有选择性,对阳离子的截留顺序为：Mg^2＋＞Na^＋＞K^＋,对阴离子的截留顺序为：Cl^-＞Br^-＞I^-.随着盐溶液浓度的增加,截留率和通量均下降,所制备的纳滤膜对无机盐的截留表现出对温度、pH的敏感性.     

Preparation of antibacterial PDMAEMA‐functionalized multiwalled carbon nanotube via atom transfer radical polymerization

Poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) was grafted onto the bromine‐functionalized multiwalled carbon nanotubes (MWNTs) by applying an atom transfer radical polymerization (ATRP). The PDMAEMA‐functionalized MWNT was characterized by Fourier transform infrared, transmission electron microscopy, Raman spectroscopy, thermal gravimetric analysis, and four‐probe resistivity meter. The wt % of PDMAEMA present in the PDMAEMA‐functionalized MWNT was estimated by applying the thermogram results for thermal gravimetric analysis. Variations of PDMAEMA content in the PDMAEMA‐functionalized MWNT were tried by changing the ATRP process conditions such as the type of ligand and copper complex, the amount of DMAEMA based on the weight of bromine‐functionalized MWNT, and the polymerization temperature. The phase behavior of PDMAEMA‐functionalized MWNT in water depending on temperature and pH value was analyzed, and the PDMAEMA‐functionalized MWNT showed the amphipathic nature. The PDMAEMA‐functionalized MWNT clearly showed an antibacterial effect against E. coli as well as S. aureus. The highest viability loss of E. coli achieved in this study was ～ 42% with the PDMAEMA‐functionalized MWNT containing 53.9 wt % of PDMAEMA. The PDMAEMA‐functionalized MWNT showed sheet resistance less than ～ 9.68 × 10³ Ω/sq. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2013     

Synthesis and characterization of thermo‐ and pH‐sensitive block copolymers bearing a biotin group at the poly(ethylene oxide) chain end

A poly(ethylene oxide)‐block‐poly(dimethylamino ethyl methacrylate) block copolymer (PEO‐b‐PDMAEMA) bearing an amino moiety at the PEO chain end was synthesized by a one‐pot sequential oxyanionic polymerization of ethylene oxide (EO) and dimethylamino ethyl methacrylate (DMAEMA), followed by a coupling reaction between its PEO amino and a biotin derivative. The polymers were charac terized with ¹H NMR spectroscopy and gel permeation chromatography. Activated biotin, biotin‐NHS (N‐hydroxysuccinimide), was used to synthesize biotin‐PEO‐PDMAEMA. In aqueous media, the solubility of the copolymer was temperature‐ and pH‐sensitive. The particle size of the micelle formed from functionalized block copolymers was determined by dynamic light scattering. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3552–3558, 2006     

Effect of molecular weight and polymer concentration on the triple temperature/pH/ionic strength-sensitive behavior of poly(2-(dimethylamino)ethyl methacrylate)

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) samples were synthesized via aqueous atom transfer radical polymerization with DP_n of 35, 151, 390, and 546 and dispersity of 1.13, 1.17, 1.20, and 1.18, respectively. All samples were exposed to temperature and pH variations at different concentration of polymer and salt (NaCl). Results indicated that cloud point (T_cl) can be controlled by changing DP_n, polymer concentration, and ionic strength of solution. According to results, T_cl of the PDMAEMA chains shifted to lower temperatures with increasing solution pH at all molecular weight ranges due to deprotonation of tertiary amine groups in polymer structure. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, higher polymer concentration acted as driving force to decrease cloud point of samples and formation of aggregates that was more predominant for higher molecular weights at alkaline media. T_cl of PDMAEMA chains decreased with increasing ionic strength even at low pH values for low molecular weight polymers.     

Acetyl‐α‐d‐mannopyranose‐based cationic polymer via RAFT polymerization for lectin and nucleic acid bindings

Functional cationic polymers carrying mannose moieties were synthesized in a facile manner by employing RAFT polymerization. Initially, a protected carbohydrate based monomer, [2‐(2,3,4,6‐tetra‐O‐acetyl‐α‐d ‐mannopyranosyloxy)ethyl methacrylate (AcManEMA)], was prepared by the O‐glycosylation of 2‐hydroxyethyl methacrylate (HEMA). Subsequently, a macroRAFT agent of poly[2‐(dimethyl)amino ethyl methacrylate] (PDMAEMA) was generated, and a further chain extension polymerization with AcManEMA was carried out in dioxane to form a acetylated mannose cationic diblock copolymer, PDMAEMA‐b‐PAcManEMA. It was attained in high yields and displayed low dispersity (Ð). Acetylated mannose moieties on the polymer were deprotected with sodium methoxide and the amines from the DMAEMA block were protonated to yield a cationic diblock glycopolymer, PDMAEMA‐b‐PManEMA. The cationic property of polymers were characterized by mixing with a negatively charged siRNA duplex and a pDNA, and aggregates of 102 and 233 nm were obtained, respectively. Agarose gel shift assay revealed that the polymers were able to retain the nucleic acids as large polymer complexes. Lectin binding assay proved that the mannose residue on the polymers were only able to bind specifically with ConA. PNA lectin was employed as a control and did not show specific binding. The cationic glycopolymer could be advantageous in targeted nucleic acids delivery in specific cells. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44947.     

Novel Polymer-Bentonite Sorbent for Recovery of Antioxidant Polyphenols from Cornus mas L. through Integrated Process Extraction/Adsorption: Optimization of Extraction Parameters by Response Surface Methodology

Here, ultrasound-assisted extraction with ultrasonic probe of total polyphenolic content from leaves of cornelian cherry (Cornus mas L.) was studied. Batch adsorption was carried out to concentrate polyphenol extract using bentonite/2-(dimethyl amino) ethyl methacrylate composite adsorbent. The extraction was optimized through face central composite design combined with response surface methodology. It was found that bentonite/2-(dimethyl amino) ethyl methacrylate composite exhibits significant adsorption capacity (2407.50 mg-GAE/g-bentonite/2-(dimethyl amino) ethyl methacrylate composite) for polyphenols in cornelian cherry leaves. It was observed that pH was the crucial factor and highest adsorption capacity was obtained at pH 10.     

ATRP in the design of functional materials for biomedical applications

Atom Transfer Radical Polymerization (ATRP) is an effective technique for the design and preparation of multifunctional, nanostructured materials for a variety of applications in biology and medicine. ATRP enables precise control over macromolecular structure, order, and functionality, which are important considerations for emerging biomedical designs. This article reviews recent advances in the preparation of polymer-based nanomaterials using ATRP, including polymer bioconjugates, block copolymer-based drug delivery systems, cross-linked microgels/nanogels, diagnostic and imaging platforms, tissue engineering hydrogels, and degradable polymers. It is envisioned that precise engineering at the molecular level will translate to tailored macroscopic physical properties, thus enabling control of the key elements for realized biomedical applications.