N-vinylacetamide Research Articles

Cytocompatible hydrogel derived from dextrin and Poly(N-Vinyl acetamide) toward controlled antimicrobial release

The work aims to develop a biopolymer-dextrin-based three-dimensional crosslinked hydrophilic material for antimicrobial delivery. The copolymer (Dxt-PNVA) has been prepared by in-situ grafting of poly(N-vinylacetamide), followed by cross-linking with N,N'-methylenebisacrylamide with dextrin. By varying the concentrations of the reactants, an optimized copolymer (Dxt-PNVA 5) with the lowest % of crosslinking has been chosen for biomedical applications. The copolymeric gel has been characterized in detail using various techniques, followed by its cytocompatibility study using HeLa Cell lines that confirm the cytocompatible nature of the material. Copolymeric gel is a suitable material for the effective release of two antimicrobials (amoxicillin trihydrate and ornidazole) from tablet formulation for a prolonged period of 24 h. The obtained data demonstrates that the cytocompatible hydrogel has the potential characteristics of a daily dose administration for amoxicillin trihydrate and ornidazole.

Design of metal salt/amide-based deep eutectic monomers toward sustainable production of ion-conductive polymers by radical polymerization

Deep eutectic electrolytes are a recent focus in the development of energy-related fields, particularly in the area of Li batteries to combine with safer, sustainable, and cost-effective electrolytes. We herein describe a solvent-free synthetic route to ion-conductive polymers from metal salt/amide-based deep eutectic monomers (DEMs), which were prepared by mixing amido-containing solid monomers with metal salts under suitable feed ratios. N-Isopropyl acrylamide (NIPAM) and N-vinylacetamide (NVA) were selected as vinyl monomers bearing an amido functional group that can act as a hydrogen bond donor. Lithium chloride (LiCl), zinc chloride (ZnCl2), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), which can act as hydrogen bond acceptors, were employed as metal salts. The simple mixing of NIPAM with solid LiTFSI in a 5:1 M ratio at 60 °C for 0.5 h afforded liquid NIPAM/0.2LiTFSI, which exhibited the characteristic eutectic effect. By mixing NIPMA with ZnCl2 in a suitable feed ratio, NIPAM/0.25ZnCl2 was obtained as a white turbid liquid at room temperature. Similarly, NVA/0.2LiCl and NVA/0.2LiTFSI were obtained as transparent liquids from solid NVA. In addition, the thermally-induced free-radical polymerization of the metal salt/amide-based DEMs in the bulk and in solution resulted in the formation of the corresponding polymers. Poly(NVA/0.2LiTFSI) exhibited the highest ionic conductivity of 2.83 × 10−6 S/cm at 50 °C. Polymeric products were also obtained by photoinduced radical polymerization from liquid DEMs without the use of volatile organic solvents under an air environment. These results reveal that the DEMs developed in this study can provide a green and sustainable process for the radically-induced production of novel ion-conductive polymers in air.

Synthesis of Poly(N-vinylamide)s and Poly(vinylamine)s and Their Block Copolymers by Organotellurium-Mediated Radical Polymerization.

Controlled polymerization of acyclic N-vinylamides, that is, N-methyl-N-vinylacetamide (NMVA), N-vinylacetamide (NVA), and N-vinylformamide (NVF), by organotellurium-mediated radical polymerization (TERP) is reported. The corresponding poly(N-vinylamide)s with controlled molecular weight and low dispersity (Ð<1.25) were obtained with high monomer conversion in all cases. This is the first report on the controlled polymerization of NVF. Hydrolysis of the polymers, in particular PNVF, occurred quantitatively under mild reaction conditions, giving structurally controlled poly(vinylamine)s. Block copolymers containing poly(N-vinylamide) and poly(vinylamine) segments were also synthesized in a controlled manner.

Synthesis of Poly(N‐vinylamide)s and Poly(vinylamine)s and Their Block Copolymers by Organotellurium‐Mediated Radical Polymerization

AbstractControlled polymerization of acyclic N‐vinylamides, that is, N‐methyl‐N‐vinylacetamide (NMVA), N‐vinylacetamide (NVA), and N‐vinylformamide (NVF), by organotellurium‐mediated radical polymerization (TERP) is reported. The corresponding poly(N‐vinylamide)s with controlled molecular weight and low dispersity (Ð&lt;1.25) were obtained with high monomer conversion in all cases. This is the first report on the controlled polymerization of NVF. Hydrolysis of the polymers, in particular PNVF, occurred quantitatively under mild reaction conditions, giving structurally controlled poly(vinylamine)s. Block copolymers containing poly(N‐vinylamide) and poly(vinylamine) segments were also synthesized in a controlled manner.

Synthesis of polystyrene@silica particles through soap-free emulsion polymerization and sol-gel reaction on polymer surfaces

Polystyrene@silica particles were produced through soap-free emulsion polymerization (SFEP) of styrene and N-vinylacetamide (NVA) via the sol-gel reactions of tetraethyl orthosilicate (TEOS) on polymer particle surfaces. Different amounts of NVA were used to prepare polystyrene particles using the SFEP process. The particles covered with poly-NVA then underwent the Stöber process to form an outer silica shell. NVA was found to stabilize the polymer colloids and improve their stability by steric effects, even after the positive charge on the polymer surface was partially neutralized by the electrostatically adsorbed TEOS, which tends to induce particle aggregation. Further, the –NH functional groups on NVA catalyzed the hydrolysis of TEOS in the sol-gel reaction to form silica. Consequently, small, monodisperse, and stable core-shell particles were formed despite having a low zeta potential.

Design of polymer particles maintaining dispersion stability for the synthesis of hollow silica particles through sol-gel reaction on polymer surfaces

To synthesize polystyrene-silica core-shell particles and silica hollow particles, soap-free emulsion polymerization was carried out using styrene and N-vinylacetamide (NVA), and the Stöber method using tetraethyl orthosilicate (TEOS) was performed on the polymer particle surfaces. Here, NVA acts as a stabilizer for the polymer colloids, maintaining dispersion stability by synthesizing hydration layers even when the electrostatic adsorption of TEOS had occurred, and as a catalyst for the sol-gel reaction. NVA was polymerized by the cationic initiator located on the surface of the polystyrene particles to maintain dispersion stability by a steric effect. Therefore, the sol-gel reactions proceeded more efficiently on the surface of polymer particles, facilitated by the much larger surface area. Finally, the polymer core was removed by heating to prepare highly monodisperse silica hollow particles.

In-situ Adsorption of Polymer Particles on Multi-wall Carbon Nanotubes Using Colloidal Techniques

A novel technique for the adsorption of polymer particles on carbon nanotubes was developed. First, the surfaces of multi-wall carbon nanotubes (MWCNTs) were coated with poly(N-vinyl acetamide) (PNVA) to confer them hydrophilicity together with good dispersion stability in water owing to a steric effect between the hydration layers. Second, the hydrophilic MWCNTs were covered with polymethyl methacrylate (PMMA) particles bearing positive charges—synthesized using V-50—through electrostatic interactions. These polymers were obtained by soap-free emulsion polymerization. The in-situ adsorption of PMMA particles on surface MWCNTs were attributed to the hydration layers of the modified MWCNTs, and electrostatic interactions between PMMA particles and the modified MWCNTs. It can be expected that the PMMA particles adsorbed on the carbon nanotubes hold the potential to serve as glue between carbon nanotube and PMMA in the composite.

Syntheses of Biologically Active 2-Arylcyclopropylamines

The 2-arylcyclopropylamine (ACPA) motif is often seen in biologically active compounds. This review focuses on the synthesis of biologically active ACPAs and categorizes, by reaction type, the synthetic methods used toward such compounds. 1 Introduction 2 Cyclopropanation Using Diazo Compounds 2.1 Styrene 2.2 Cinnamate 2.3 Vinyl Phthalimide 2.4 Vinyl Acetamide 2.5 Oxazolone 2.6 Diketopiperazine 3 Cyclopropanation Using Ylides 3.1 Cinnamate 3.2 Nitrostyrene 3.3 Oxirane 3.4 Nitroacetate 4 Transformation of Cyclopropanes 4.1 Iodocyclopropane 4.2 Aminocyclopropane 5 Miscellaneous Methods 5.1 Kulinkovich Reaction 5.2 Three-Component Reaction 5.3 Intramolecular Nucleophilic Cyclization 5.4 Intramolecular Mitsunobu Reaction 5.5 Rearrangement from Cyclobutanone 6 Summary

Thermal Treatment of Poly (N-vinylformamide) Produced Hydrogels Without the Use of Chemical Crosslinkers.

Hydrogel preparations using poly(N-vinylformamide) (PNVF) and poly(N-vinylacetamide) (PNVA), which are composed of non-conjugated vinyl monomers, N-vinylformamide (NVF) and N-vinylacetamide (NVA), were investigated without chemical crosslinkers. Hydrogen bonding interaction between the polymers and poly(ethylene glycol) have been firstly attempted to result in unstable film, which is easily soluble in water. On the other hand, the simple thermal treatment of the PNVF films at 200 °C for several hours produced the hydrogels after water immersion, although PNVA did not produce any hydrogels under the same condition. The swelling ratios of the formed hydrogel ranged from 100 to 250. The analysis of the supernatant reveals the structural change at alpha proton of PNVF. Furthermore, the decrease of molecular weights were observed by SEC analysis when the hydrogels formed. The possible mechanism of the crosslinking reaction is also discussed. The present study provides the novel method to prepare PNVF hydrogels without the use of chemical crosslinkers.

Synthesis of hydrocolloid through polymerization of styrene and N-vinyl acetamide by AIBN

The soap-free emulsion polymerization of styrene with hydrophilic monomer, N-vinyl acetamide (NVA), using oil-soluble initiator was carried out to synthesize polymeric particles with good dispersion stability and improve the polymer yield. As a result, it was found that the polymer yield and dispersion stability were enhanced by the promotion of polymerization by the dissolved monomers and hydrogen bonding between NVA on the particle surface and water molecules in the bulk. Accordingly, this polymer colloid showed the nature of hydrocolloid by their hydration layers because its dispersion stability was kept even when the electrolytes were added to the system. In the conventional soap-free emulsion polymerization, the counter ions including the water-soluble initiators were remained in the water phase. However, because all of chemical components in the present study were consumed for the polymerization, the impurities except polymers were hardly remained in the bulk.

Rapid Photogelation of Amphiphilic Poly(N-vinylacetamide) Bearing Coumarin Moiety in Water and Organic Solvents

Abstract Copolymers of N-vinylacetamide (NVA) and its derivative (NVA-coumarin) were synthesized bearing photoresponsive moieties. The dimerization of NVA-coumarin was confirmed under irradiation with ultraviolet light (&amp;gt;280 nm). Copolymers showed photoresponsiveness and amphiphilic characteristics, based on both poly(NVA) and coumarin.

Amphiphilic Poly(N‐vinyl acetamide) Gels Strengthened with Swelling Solvent

Improving fragility is important for the practical application of gels. In this study, the mechanical strength of gels composed of poly(N‐vinyl acetamide) (PNVA) and glycols is investigated focusing on the retained solvent in the gels. The solvent for the PNVA hydrogel is adequately replaced by various glycols. Using poly(ethylene glycol) (PEG) with molecular weights of 400 or 600 g mol−1, the compressive strength of the gel is dramatically enhanced to approximately 10 MPa while that of hydrogel is 0.2 MPa. This is because of solvent viscosity, interaction between PEG and PNVA, and the favorable aggregation of the PNVA. From FTIR spectroscopy investigations, the absorption bands of the carbonyl and amino groups of PNVA gels with PEG400 are shifted as compared with PNVA gels in water, suggesting hydrogen bond formation. image

Investigation of the Kinetic Hydrate Inhibitor Performance of a Series of Copolymers ofN-Vinyl Azacyclooctanone on Structure II Gas Hydrate

A series of copolymers of N-vinylazacyclooctanone (VACO) with more hydrophilic monomers, including the 5–7 ring N-vinyl lactams, N-vinyl-N-methyl acetamide (VIMA), and N-vinyl acetamide (NVA), have been synthesized. Their performance as kinetic hydrate inhibitors (KHIs) was compared to poly(N-vinylazacyclooctanone) (PVACO) homopolymer in high pressure rocking cells using a Structure II hydrate-forming natural gas mixture. The best 1:1 copolymer between any two of the four N-vinyl lactams was found to be for VP/VACO copolymer. 1:1 VACO/VIMA copolymers were also shown to be a superior KHI to PVACO, whereas copolymers of other ratios of these two monomers were less effective KHIs. 2-Butoxyethanol (BGE) was also found to be a good solvent and synergist for 1:1 VACO/VIMA copolymers. Finally, 1:1 N-vinyl lactam/NVA copolymers were shown to have worse KHI performance than the equivalent 1:1 N-vinyl lactam/VIMA copolymers at similar molecular weights.

One-pot controlled synthesis of double thermoresponsive N-vinylcaprolactam-based copolymers with tunable LCSTs

N-Vinylcaprolactam (NVCL) was copolymerized statistically for the first time in a controlled manner with hydrophilic N-vinylamide or hydrophobic vinylester monomers in order to precisely tune up and down the lower critical solution temperature (LCST) of the resulting copolymers. The incorporation of these segments in complex architectures was also considered. Several narrowly distributed NVCL-based copolymers were prepared by cobalt-mediated radical polymerization (CMRP) using the bis-(acetylacetonato)cobalt(II) complex as a controlling agent and N-methyl-N-vinylacetamide (NMVA), N-vinylacetamide (NVA), vinyl acetate (VAc) or vinyl pivalate (VPi) as comonomers. PNVCL-containing block copolymers having two discrete LCSTs were also synthesized following a one-pot strategy based on the sequential CMRP of NVCL followed by the copolymerization of NMVA with the residual NVCL. Upon gradual heating of aqueous solutions of such double thermoresponsive copolymers, we noticed a transition from free chains to micelles before full dehydration and collapse of the block copolymers. These advances represent a significant step towards the development of a platform based on thermoresponsive PNVCL copolymers with a single phase separation or multistep assembly behaviors.

Key Role of Intramolecular Metal Chelation and Hydrogen Bonding in the Cobalt‐Mediated Radical Polymerization of N‐Vinyl Amides

This work reveals the preponderance of an intramolecular metal chelation phenomenon in a controlled radical polymerization system involving the reversible trapping of the radical chains by a cobalt complex bis(acetylacetonato)cobalt(II). The cobalt-mediated radical polymerization (CMRP) of a series of N-vinyl amides was considered with the aim of studying the effect of the cobalt chelation by the amide moiety of the last monomer unit of the chain. The latter reinforces the cobalt-polymer bond in the order N-vinylpyrrolidone<N-vinyl caprolactam<N-methyl-N-vinyl acetamide, and is responsible for the optimal control of the polymerizations observed for the last two monomers. Such a double linkage between the controlling agent and the polymer, through a covalent bond and a dative bond, is unique in the field of controlled radical polymerization and represents a powerful opportunity to fine tune the equilibrium between latent and free radicals. Possible hydrogen bond formation is also taken into account in the case of N-vinyl acetamide and N-vinyl formamide. These results are essential for understanding the factors influencing Co-C bond strength in general, and the CMRP mechanism in particular, but also for developing a powerful platform for the synthesis of new precision poly(N-vinyl amide) materials, which are an important class of polymers that sustain numerous applications today.

Fouling-resistant properties of a surface-modified poly(ether sulfone) ultrafiltration membrane grafted with poly(ethylene glycol)-amide binary monomers

Poly(ether sulfone) (PES) membrane surfaces were modified by grafting poly(ethylene glycol) methyl ether methacrylate (PEG) with vinylamides including N-vinylformamide (NVF), N-vinylacetamide (NVA) or N-methyl-N-vinylacetamide (MVA) via a photo-induced graft polymerization (PGP) method coupled with a recently developed high throughput platform (HTP) technology. Synergistic fouling reduction by grafting PEG with a vinylamide was observed. Fouling was orchestrated using 1 mg mL −1 bovine serum albumin (BSA) as a model foulant. The optimum composition for grafting each PEG–vinylamide pair in terms of fouling reduction, permeation resistance and protein sieving was sought. Fouling index, ℜ, was used to quantify the intensity of fouling. The degree of grafting (DG) of PEG and vinylamides were analyzed using FTIR–ATR spectroscopy. Lower fouling (reduced ℜ value) was observed with mixed monomer as compared with single monomer grafts. The lowest fouling index (ℜ = − 0.56 ± 0.29) was obtained by grafting 0.06 mol L −1 PEG and 0.14 mol L −1 NVA. This also gave a higher permeability as compared with that before BSA fouling. Using a Hansen solubility analysis with degree of grafting, the data suggests pore-narrowing by grafting during the surface modification process.

Design and synthesis of N-vinylacetamide derivative with bulky group by nucleophilic substitution reaction

Cyclohexyl, adamantyl, and triphenylmethyl groups were employed for the nucleophilic substitution reaction with N-vinylacetamide (NVA), in order to investigate the bulky substituents effects on molecular structures in N-vinyl monomers. Although normal alkyl halides were known to produce N-substituted NVA, alkyl halides with secondary and tertiary carbons did not occur nucleophilic substitution reaction. On the contrary, triphenylmethyl group was introduced into β-position on NVA, accompanied with hydrogen transfer. The refined crystal structure of β-triphenylmethyl-N-vinylacetamide revealed intermolecular linear hydrogen bonds and aromatic bulky triphenylmethyl group supported the structure.

Interpenetrating Polymer Networks of Poly(N-vinylacetamide) and Poly(acrylic acid) Applied to Novel Amphiphilic Drug Release Substrates with Mechanically Modified Strengths

Abstract Gels with interpenetrating polymer networks were prepared with N-vinylacetamide (NVA) and acrylic acid (AAc) as novel substrates for transdermal therapeutic systems. The gelation of NVA at 1 M in AAc gel sustained the amphiphilic character, and a poorly water-soluble drug was kept in the gel with ethanol as solvent. Mechanical strengths were five times larger in value than those of simple poly(N-vinylacetamide) gels.

Cell Adhesion and Proliferation on Poly(N-vinylacetamide) Hydrogels and Double Network Approaches for Changing Cellular Affinities

Poly(N-vinylacetamide) hydrogels (PNVA gels) were synthesized to investigate their basic characteristics for biomedical applications such as water contact angles, protein uptake, and mouse fibroblasts (L-929) cell adhesion. Because PNVA gels show hydrophilic features, double network (DN) hydrogels were prepared by the secondary polymerization of N-vinylacetamide (NVA) or acrylamide (AAm) in PNVA gels (NVA/NVA DN gels and NVA/AAm DN gels, respectively), in order to vary PNVA gel features for biocompatibility. Contact angles for both DN gels decreased to around 20 degrees, whereas both PNVA and PAAm gels were over 30 degrees. On the other hand, more protein tended to adsorb to DN gels than single network hydrogels. Compared to PNVA gel, cell adhesion and proliferation on NVA/NVA DN gel were improved with less swelling ratio and much protein uptake, while no significant difference was observed on NVA/AAm DN gel, probably due to more hydrophilic character, supported by lowest water contact angle. These complicated structure change in DN gels would provide a new methodology for tuning the biocompatibility of hydrogels and for controlling surface hydrophilic characteristics and network structures.

Diversification of Nonionic Amphiphilic Poly(N-vinylacetamide) Hydrogels by a Double Network Approach

Abstract The amphiphilic aprotic vinyl monomer, N-vinylacetamide (NVA), was firstly employed to fabricate double network (DN) hydrogels in water at 37 °C. Although N,N-methylenebisacrylamide as a crosslinker did not form hydrogels, novel crosslinker which is based on the structure of NVA was effective in creating first and second network hydrogels. DN structures of nonionic NVA hydrogels will expand the pool of various functional hydrogels, as well as give rise to stronger NVA hydrogel preparations.