Tertiary amine methacrylate based polymers as Corrosion Inhibitors in double distilled water. Part I

In the current study, the inhibitive performances of tertiary amine methacrlate based water soluble diblock copolymers on the corrosion behaviour of AISI 304 stainless steel were investigated in double distilled water (DDW, at pH = 7.6) using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and inductively coupled plasma optical emmision spectrometry (ICP OES) methods. Related diblock copolymers were poly[2-(dimethylamino)ethylmethacrylate] (PDMA), poly[2-(diethylamino)ethylmethacrylate] (PDEA), poly[2-(diisopropylamino)ethylmethacrylate] (PDPA) homopolymers and poly[2-(dimethylamino)ethylmethacrylate]- b-poly[methylmethacrylate] (PDMA-b-PMMA), poly[2-(diethylamino)ethylmethacrylate]-bpoly[ methylmethacrylate] (PDEA-b-PDMA) and poly[2-(diisopropylamino)ethylmethacrylate]-b-poly[2-(dimethylamino) ethylmethacrylate] (PDPA-b-PDMA). Diblock copolymers having different molecular weight and different comonomer ratios. Polarisation curves indicated that all the studied polymers were acting as a mixed type inhibitors. All electrochemical measurements showed that inhibition efficiencies increased with an increase in the inhibitor concentration. It was determined that the increase of inhibitor efficiency by concentration resulted from the adsorption of polymers to metal surface, and the adsorption fitted to Langmuir adsorption equation. Adsorption equilibrium constant (Kads) and free energy of adsorption(ΔGads), which were thermodynamic parameters of adsorption were calculated by benefiting from the drawn adsorption isotherms. The variation in inhibitive efficiency mainly depended on the type and the nature of the substituents present in the inhibitor molecule and also depended on the molecular weight of the inhibitors. The best inhibition in DDW showed VB207 diblock copolymer. Surface images obtained with SEM, EDX and AFM methods, determined by verifying these results that inhibitors decreased the dissolution of metal, and prevented the corrosion

Dark current reduction in ultraviolet metal-semiconductor-metal photodetectors based on wide band-gap semiconductors

Photodetectors on semi-insulating GaN templates were demonstrated. They exhibit lower dark current compared to photodetectors fabricated on regular GaN templates. Similar behavior observed in photodetectors fabricated on epitaxially thick SiC templates. © 2009 IEEE

Thermo-responsive Diblock Copolymer Worm Gels in Non-polar Solvents

Benzyl methacrylate (BzMA) is polymerized using a poly(lauryl methacrylate) macromolecular chain transfer agent (PLMA macro-CTA) using reversible addition–fragmentation chain transfer (RAFT) polymerization at 70 °C in n-dodecane. This choice of solvent leads to an efficient dispersion polymerization, with polymerization-induced self-assembly (PISA) occurring via the growing PBzMA block to produce a range of PLMA–PBzMA diblock copolymer nano-objects, including spheres, worms, and vesicles. In the present study, particular attention is paid to the worm phase, which forms soft free-standing gels at 20 °C due to multiple inter-worm contacts. Such worm gels exhibit thermo-responsive behavior: heating above 50 °C causes degelation due to the onset of a worm-to-sphere transition. Degelation occurs because isotropic spheres interact with each other much less efficiently than the highly anisotropic worms. This worm-to-sphere thermal transition is essentially irreversible on heating a dilute solution (0.10% w/w) but is more or less reversible on heating a more concentrated dispersion (20% w/w). The relatively low volatility of n-dodecane facilitates variable-temperature rheological studies, which are consistent with eventual reconstitution of the worm phase on cooling to 20 °C. Variable-temperature 1H NMR studies conducted in d26-dodecane confirm partial solvation of the PBzMA block at elevated temperature: surface plasticization of the worm cores is invoked to account for the observed change in morphology, because this is sufficient to increase the copolymer curvature and hence induce a worm-to-sphere transition. Small-angle X-ray scattering and TEM are used to investigate the structural changes that occur during the worm-to-sphere-to-worm thermal cycle; experiments conducted at 1.0 and 5.0% w/w demonstrate the concentration-dependent (ir)reversibility of these morphological transitions

Facile formation of highly mobile supported lipid bilayers on surface-quaternized pH-responsive polymer brushes

Poly(2-dimethylamino)ethyl methacrylate) (PDMA) brushes are grown from planar substrates via surface atom transfer radical polymerization (ATRP). Quaternization of these brushes is conducted using 1-iodooctadecane in n-hexane, which is a non-solvent for PDMA. Ellipsometry, AFM, and water contact angle measurements show that surface-confined quaternization occurs under these conditions, producing pH-responsive brushes that have a hydrophobic upper surface. Systematic variation of the 1-iodooctadecane concentration and reaction time enables the mean degree of surface quaternization to be optimized. Relatively low degrees of surface quaternization (ca. 10 mol % as judged by XPS) produce brushes that enable the formation of supported lipid bilayers, with the hydrophobic pendent octadecyl groups promoting in situ rupture of lipid vesicles. Control experiments confirm that quaternized PDMA brushes prepared in a good brush solvent (THF) produce non-pH-responsive brushes, presumably because the pendent octadecyl groups form micelle-like physical cross-links throughout the brush layer. Supported lipid bilayers (SLBs) can also be formed on the non-quaternized PDMA precursor brushes, but such structures proved to be unstable to small changes in pH. Thus, surface quaternization of PDMA brushes using 1-iodooctadecane in n-hexane provides the best protocol for the formation of robust SLBs. Fluorescence recovery after photobleaching (FRAP) studies of such SLBs indicate diffusion coefficients (2.8 ± 0.3 μm s–1) and mobile fractions (98 ± 2%) that are comparable to the literature data reported for SLBs prepared directly on planar glass substrates

Polymerization-Induced Self-Assembly of Block Copolymer Nano-objects via RAFT Aqueous Dispersion Polymerization

In this Perspective, we discuss the recent development of polymerization-induced self-assembly mediated by reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization. This approach has quickly become a powerful and versatile technique for the synthesis of a wide range of bespoke organic diblock copolymer nano-objects of controllable size, morphology, and surface functionality. Given its potential scalability, such environmentally-friendly formulations are expected to offer many potential applications, such as novel Pickering emulsifiers, efficient microencapsulation vehicles, and sterilizable thermo-responsive hydrogels for the cost-effective long-term storage of mammalian cells

Novel zwitterionic ABA-type triblock copolymer for pH-and salt-controlled release of risperidone

An ABA-type triblock copolymer was synthesized through group-transfer polymerization by using poly[2-(diethylamino) ethyl methacrylate] (PDEA) as A block and poly[2-(dimethylamino) ethyl methacrylate] (PDMA) as B block. By utilizing the 1,3-propane sultone to obtain polyzwitterionic triblock copolymer under moderate conditions, PDMA block of the triblock copolymer has been selectively betainized. The selectively betainized block copolymer and its precursor were molecularly dissolved in acidic aqueous media without any use of cosolvent at room temperature. In both cases, an increase in solution pH caused near monodisperse cationic or neutral flower-like micellization with hydrophobic PDEA-core at basic aqueous solution. However, at higher polymer concentrations where precursor triblock copolymer does not exhibit any gelling behavior (10% and higher), polyzwitterionic copolymer derivative can be gelated as a result of inter-chain integration of polyzwitterionic groups. Furthermore, the load of risperidone (RISP) into gel matrix and release studies have been successively realized. The results indicated that the betainized novel gel is appropriate for using as a pH-and salt-controlled risperidone-releasing system. © 2016 Taylor and Francis Group, LLC

The synthesis and solution behaviors of novel amphiphilic block copolymers based on d-galactopyranose and 2-(dimethylamino)ethyl methacrylate

A series of novel stimuli-responsive AB, ABA, and BAB type block copolymers based on 6-O-methacryloyl-1,2:3,4-di-O-isopropylidene-d-galactopyranose (MAIpGP:A block) and 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA: B block) were synthesized via ATRP techniques using ethyl 2-bromoisobutyrate (EBiB) as monofunctional ATRP initiator in the case of diblock copolymer and diethyl meso-2,5-dibromoadipate (DEDBA) as bifunctional ATRP initiator in the case of triblock copolymers. The PMAIpGP blocks of the AB, ABA, and BAB type linear block copolymers were converted to water soluble PMAGP blocks via deprotection process under mild acidic conditions. Both proton NMR and DLS studies demonstrated that block copolymers were temperature-sensitive, whereby the lower critical solution temperature (LCST) of polymers varied with the polymerization degrees of comonomers in the block copolymers. LCST was determined to be between ~35 C and 55 C depending on the type and the comonomer compositions of the block copolymers. It was observed that an increase on the percentage of hydrophilic PMAGP block in block copolymer caused an increase on the LCST value as expected. © 2013 Elsevier Ltd. All rights reserved.Bülent Ecevit ÜniversitesiThis work was supported by Bülent Ecevit University. Research Fund, Turkey (AFP project no: 2011-10-03-09). Appendix

Tertiary amine methacrylate based polymers as corrosion ınhibitors in hcl solution. Part II

In this study, the inhibitive performance of novel synthesised water-soluble of different molecular weight diblock copolymers of derivative methyl methacrylate (VB84, VB206, VB207, VB361, VB371,VB406) on the corrosion behaviour of AISI 304 stainless steel in 10–3 M HCl containing various concentrations of polymers was investigated using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), scanning electron microscopy(SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and inductively coupled plasma optical emmision spectrometry (ICP-OES) methods. Polarisation curves indicated that all studied polymers were acting as mixed type inhibitors. All electrochemical measurements showed that inhibition efficiencies increased with increasing polymer concentration. It was determined that the increase of inhibitor efficiency by concentration resulted from the adsorption of polymers to metal surface, and the adsorption fitted to the Langmuir adsorption equation. The variation in inhibitive efficiency mainly depends on the type and the nature of the substituents present in the polymer molecule and also depends on the molecular weight of the polymer. The best inhibition in 10-3 M HCl shows VB84 homopolymer. Surface images obtained with SEM, EDX, and AFM methods determined by verifying these results that inhibitors decrease the dissolution of metal, prevented the corrosion

Production of LMWH-conjugated core/shell hydrogels encapsulating paclitaxel for transdermal delivery: In vitro and in vivo assessment

PubMed ID: 30708013Topical applications that reduce systemic toxic effects while increasing therapeutic efficacy are a promising alternative strategy. The aim of this study was to provide an enhanced transdermal delivery of low molecular weight heparin (LMWH) through the stratum corneum by using cationic carrier as a novel permeation enhancer. Recent studies have shown that heparin-conjugated biomaterials can be effective in inhibiting tumor growth during cancer treatment due to their high ability to bind growth factors. Paclitaxel (PCL) was co-encapsulated into the same cationic carrier for the purpose of improving of therapeutic efficacy for a combined cancer treatment with LMWH. In vitro and in vivo studies showed that the LMWH and PCL release was significantly affected by polymer molecular weight and block composition. Skin penetration tests have indicated that larger amounts of LMWH were absorbed from LMWH-gel conjugate through SC, than aqueous formula. However, it was found that the plasma transition of LMWH released from gel conjugate was lower compared to the plasma concentration of LMWH released from aqueous solution. It is recommended that PCL-loaded LMWH-conjugated core/shell hydrogels can be used as promising drug release systems for transdermal applications that can improve therapeutic efficacy and reduce side effects in a combined cancer treatment. © 2019 Elsevier B.V.3501Firstly, I would like to thank my supervisor Prof. Dr. Vural Bütün for his constant support and kind advices. This research is supported by TUBITAK (The Scientific and Technological Research Council of Turkey ) under project 3501 - Career Development Program (CAREER). I am grateful to TÜBİTAK for giving me an opportunity to realize of this project (Project number is 113Z584). I would also thank Mehtap Şahin and Hüseyin Şahin for their helps in the synthesis of copolymers