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Recent Developments in MOF-Polymer Composites
Published in Ram K. Gupta, Tahir Rasheed, Tuan Anh Nguyen, Muhammad Bilal, Metal-Organic Frameworks-Based Hybrid Materials for Environmental Sensing and Monitoring, 2022
Polymerization within the confined spaces (nanochannels) of MOFs allows the control of the environment around the polymers, their molecular weight, stereoregularity, polymer sequence, and their chain arrangement. Unique host guest synergies are observed upon encapsulating functional polymers into MOFs. The first example of polymerization in the nanochannels of [M2(1,4-benzenedicarboxylate)2(triethylenediamine)] (M = Cu2+ or Zn2+) was performed by Uemura et al. [4] and is presented in Figure 3.2. Polymerization of the styrene (St) monomer was induced by heating the mixture with a radical initiator 2,2-azobis(isobutyronitrile) to construct the final composite of MOFs with polystyrene. XRD data of the composite confirms the retention of the pore structure of the MOFs during polymerization. For the analysis of the resulting polymer, the MOF structure was decomposed to obtain PSt. Due to the effective protection of the polymer inside the nanochannels, the propagating radical was free from side reactions and the recovered PSt showed homogenous molecular weight distribution as compared to a polymer synthesized using traditional techniques.
N-(2-hydroxypropyl)-methacrylamide] for Biomedical Applications
Published in Raphael M. Ottenbrite, Sung Wan Kim, Polymeric Drugs & Drug Delivery Systems, 2019
Rong-Zheng Lu, Pavla Kopečková, Jindrich Kopeček
Semitelechelic HPMA polymers were synthesized by free radical polymerization of HPMA using 2,2’-azobis(isobutyronitrile) (AIBN) as the initiator and alkyl mercaptans as chain transfer agents. Alkyl mercaptans with different functional groups, namely, 2-mercaptoethylamine, 3-mercapto-propionic acid, 3-mercaptopropionic hydrazide, and methyl 3-mercapto-propionate, were used as the chain transfer agents; ST HPMA polymers with amino, carboxy, hydrazo, and methyl ester end groups, respectively, were prepared (Scheme 1) [20]. The functional end groups of the ST HPMA polymers can be transformed to other active functional groups. For example, ST-PHPMA-COOCH3 was transformed to ST-PHPMA-CONHNH2 by the reaction with an excess of hydrazine [20]. Semitelechelic polymers with N-hydroxysuccinimide (HOSu) ester end groups ST-PHPMA-COOSu were synthesized by esterification of ST-PHPMA-COOH with a large excess of N-hydroxysuccinimide with dicyclohexyl carbodiimide (DCC) as coupling agent. The ST-PHPMA-COOSu will react with amino groups on proteins and on biomedical surfaces. The molecular weight of the ST-PHPMA after polymer analogous esterification did not change, confirming the assumption that the secondary OH groups of the HPMA monomer were not reactive under the experimental conditions used [20]. Synthesis of ST-PHPMA polymers [20].
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Published in Eli Ruckenstein, Hangquan Li, Chong Cheng, Concentrated Emulsion Polymerization, 2019
Xiang Zheng Kong, Eli Ruckenstein
Styrene (St), methyl methacrylate (MMA), and acrylic acid (AA) were purchased from Aldrich, and the inhibitors were removed prior to polymerization by passing the monomers through an inhibitor remover prepacked column (Aldrich). The monomer, octamethyl tetracyclosiloxane (D4, Aldrich), the coupling agents between the core, and the shell polymers, namely, 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl cyclotetrasiloxane (VD4, Aldrich) and 3-(trimethoxylsilyl)propyl methacrylate (MATS, 98%, Aldrich), as well as sodium dodecylbenzene sulfonate (SDBS, Aldrich), were used as received. A linear alkylbenzene sulfonic acid (ABSA, assay 98%, Alfa) was employed as catalyst and surfactant in the cationic polymerization of D4. ABSA (RC6H4SO3H) is a mixture of alkylbenzene sulfonic acids with 1 wt % R = C10, 40 wt % R = C11, 28 wt % R = C12, and 31 wt % C13 and higher alkyls. A 3N solution of sodium hydroxide (99.99%, Aldrich) was prepared and employed as catalyst in the anionic emulsion polymerization of D4. The initiators employed in radical polymerizations (ammonium persulfate, APS, 99.99%, Aldrich; or azobis-isobutyronitrile, AIBN, Polysciences Inc.) were used as received. Distilled and deionized water with a conductivity of 0.05 μS/cm was employed.
Synthesis of PVA/PVP based hydrogel for biomedical applications: a review
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Mohamed Saad Bala Husain, Arun Gupta, Basma Yahya Alashwal, Swati Sharma
The integral components of the hydrogels synthesis are the monomer, initiator and cross-linker for the hydrogels prepared by radical polymerization (Mishra, Vats, and Clark 2015). Aside from radical polymerization of mixtures of vinyl monomers, chemically crosslinked hydrogels can also be obtained by radical polymerization of polymers derivatized with polymerizable groups (macromonomer) Figure 1 (Ebara et al. 2014). In general, hydrogels can be prepared from free radical polymerization with tunable mechanical properties and variable gel thicknesses by modulating the polymer chain length, cross-linking density, and reaction times (Jaegle et al. 2017). Polymerization is usually initiated by free-radical generating compounds such as benzoyl peroxide, 2,2-azo-isobutyronitrile (AIBN), and ammonium peroxide sulphate or by using UV-, gamma- or electron beam-radiation (Caló and Khutoryanskiy 2015).
Selective removal of pyridine in fuel by imprinted polymer (poly 4-vinyl aniline-co-DVB) as adsorbent
Published in Petroleum Science and Technology, 2019
Sinazo Mathidala, Adeniyi S. Ogunlaja
To 10 mL of 4-vinyl aniline, 5 mL of divinyl benzene was added, this was followed by the addition of 0.1065 g of pyridine. The resulting mixture was stirred until a homogenous mixture was obtained. Polymerization was performed under nitrogen atmosphere at 70 °C for 48 h in the presence of 0.05 g of 2,2-azobis(isobutyronitrile) (AIBN). After the process of polymerization was completed, the resulting imprinted polymer was crushed gently, and then washed several times with warm ethanol/acetonitrile (1:1) to remove the template “pyridine” molecule (Scheme 1), thereafter air dried and weighed (2.1 g). The use of a cross linker is advantageous for the rapid solidification of adsorbent as well as for preserving template molecule cavities.
Control of interfacial structures and anti-platelet adhesion property of blood-compatible random copolymers
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Daiki Murakami, Yuto Segami, Tomoya Ueda, Masaru Tanaka
PMEA and PBA were synthesized as reported previously [31]. The random copolymers of PMEA and PBA were synthesized by free radical copolymerization, using 2,2′-azobis-isobutyronitrile (AIBN) as an initiator in 1,4-dioxane at 75 °C for 6 h. The reaction scheme is shown in Scheme 1. To vary the composition of the copolymers, monomer feed ratios of 78:22, 47:53 and 25:75 (MEA: BA, mol%) were used. The copolymers synthesized with feed ratios of 78:22 and 47:53 were purified by reprecipitation in n-hexane three times. In case of the copolymer in the feed ratio of 25:75, it was reprecipitated in water four times, because the polymer was soluble in hexane due to the high BA ratio. All three were stirred in water over 24 h.