Preparation and antimicrobial activity of terpene-based polyurethane coatings with carbamate group-containing quaternary ammonium salts

A series of novel carbamate group-containing quaternary ammonium salts (QASs) have been synthesized, which were subsequently used as antimicrobial agent and incorporated into polyurethane coatings through crosslinking with terpene-based polyol and polyisocyanate. The chemical structures of QASs were characterized by FT-IR, ¹H NMR, and ¹³C NMR. The effects of QASs on the properties of coatings were investigated. The results showed that the resulting coatings exhibited significant antimicrobial activity against both Staphylococcus aureus and Escherichia coli by introducing QASs into the polyurethane networks. Furthermore, with the increasing of QAS content, the antimicrobial activity and adhesion of the coatings were enhanced, while the pencil hardness, water resistance and thermal stability of the coatings were decreased.     

Antimicrobial polyurethane coatings based on ionic liquid quaternary ammonium compounds

The antimicrobial effect of ionic liquids (ILs) as comonomers in polyurethane surface coatings was investigated. Ionic liquid-containing coatings were prepared from a hydroxyl end-capped liquid oligoester and a triisocyanate crosslinker. Three different commercially available hydroxyl end-capped ionic liquids were covalently incorporated into the coatings in order to end up with antimicrobial polyurethane films. The ionic liquids used in this study were chosen because of their structural similarities to other antimicrobial quaternary ammonium compounds (QACs). Prepared films have been examined against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli type bacteria, and showed strong antimicrobial activity.     

Zwitterionic siloxane-polyurethane fouling-release coatings

An approach to the design of polyurethane coatings having amphiphilic/zwitterionic surfaces via a self-stratification approach has been explored for marine non-fouling applications. Zwitterionic materials such as poly(sulfobetaine methacrylate) poly(SBMA), are used as non-fouling materials due to their protein resistance properties. ABA-type triblock copolymers, poly(SBMA)-block-PDMS-block-poly(SBMA), having PDMS as the central block and poly(SBMA) as the flanking blocks with secondary amines at the junction points were synthesized using ring opening equilibration polymerization (ROEP), Michael addition and atom transfer radical polymerization (ATRP). A series of triblocks were synthesized and incorporated into a polyurethane coating system and were evaluated for water contact angle (WCA), surface energy (SE) and pseudobarnacle adhesion (PB). The fouling-release (FR) performance of the coatings was evaluated in the laboratory using a suite of representative marine organisms. The coatings showed excellent FR performance toward the bacterium Halomonas pacifica and the diatom (microalga) Navicula incerta while the bacterium Cellulophaga lytica and sporelings of the green macroalga Ulva linza showed a relatively higher affinity for amphiphilic coating surfaces when compared to a series of standard control coatings.     

Rechargeable antimicrobial coatings for poly(lactic acid) nonwoven fabrics

A novel heterocyclic N-halamine acetate homopolymer was synthesized and characterized by ATR-IR, NMR and MALDI-TOF spectroscopy and TGA and DSC analysis. The homopolymer was coated onto poly(lactic acid) (PLA) meltblown nonwoven fabric, and the surfaces were rendered biocidal upon exposure to dilute sodium hypochlorite solution. The coatings were quite stable versus UVA and florescent light exposure. Moreover, they exhibited long-term shelf-life stability, and they were rechargeable when oxidative chlorine on the surfaces was partially exhausted after three months storage. It was found that the chlorinated fabrics exhibited effective antimicrobial activity with about six logs inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 30 min of contact time. The coated PLA possesses potential for use in antimicrobial food packaging, filters, and hygiene products.     

Development of moisture cure polyurethane–urea coatings using 1,2,3-triazole core hyperbranched polyesters

This article reports the development of moisture cure polyurethane–urea coatings. The coating has been developed using different generations of novel 1,2,3-triazole core containing hyperbranched polyester polyols (THBP). For the synthesis of THBP, the core molecule, tetra hydroxyl-terminated di-triazole (THTD), has been synthesized by click reaction involving ethylene diazide and 2-butyne-1,4-diol. The polycondensation reaction between the core THTD and 2,2-bis (hydroxymethyl) propionic acid (Bis-MPA) at different mole ratios has been used to get first (THBPG-1), second (THBPG-2), and third (THBPG-3) generations of triazole core hyperbranched polyesters. The structural investigations of these THBPs have been carried out by ¹H NMR, ¹³C NMR, and FTIR spectroscopy. The different generations of THBPs were further reacted with 1-isocyanato-4-[(4-isocyanatocyclohexyl) methyl] cyclohexane (H₁₂-MDI) at OH:NCO ratio of 1:1.2 to get –NCO terminated triazole core hyperbranched polyurethanes. They were cured under atmospheric moisture to get hyperbranched polyurethane–urea coatings and were named as THBPUG-1, THBPUG-2, and THBPUG-3. FTIR has been used to confirm the formation of polyurethane coatings. The TGA and DMTA have been used to determine the thermal stability and dynamic mechanical properties of the coatings, respectively. The corrosion resistance properties of the coatings have been studied by salt spray and electrochemical test. The coatings were also evaluated for microbial resistance. The results indicate that the thermal stability, glass transition temperature, and corrosion resistance properties increase with an increase in generation number of THBPs used for coating development. All three generations of coating films show excellent antimicrobial activity. Based on overall combined structure–property relationship study, these types of coatings will be useful as multifunctional applications in marine and moist environments.     

Development of PU Coatings from Neem Oil Based Alkyds Prepared by the Monoglyceride Route

This work deals with the preparation of alkyd resins from neem oil and their utilization in preparation of polyurethane coatings. Alkyd resins were synthesized by reaction of neem oil monoglycerides with four different divalent acids like phthalic anhydride, maleic anhydride, itaconic acid, and dimer fatty acid. The alkyds formation was studied by determining the acid number of the reaction mixture at regular intervals of time and the extents of the polyesterification reactions were calculated during the formation of alkyds. The structures of synthesized alkyds were confirmed by FT‐IR and ¹H‐NMR spectroscopic analysis and also by end group analysis such as hydroxyl and acid values. The synthesized alkyds were reacted with TDI to prepare PU coatings and their performance was compared with PU coatings prepared from a commercial alkyd.     

A high-efficacy and regenerable antimicrobial resin containing quaternarized N-halamine groups

A novel macroporous cross-linked antimicrobial resin containing quaternarized N-halamine groups, poly(1-chloro-5,5-dimethylhydantoinyl-3-ethyl-p-ethenylphenylmethyl dimethylammonium chloride) (Cl-PSQH), has been synthesized by a facile three-step reaction. The as-prepared resins were characterized by FT-IR, X-ray photoelectron spectroscopy, and zeta-potential measurement. Antimicrobial tests showed that Cl-PSQH was capable of about a 7-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 1 min of contact. Also, its regenerability and preliminary storage stability were investigated.     

Synthesis of mechanically robust antimicrobial nanocomposites by click coupling of hyperbranched polyurethane and carbon nanotubes

This study demonstrates that mechanically robust antimicrobial nanocomposites of multiwalled carbon nanotubes (MWCNTs) and hyperbranched polyurethane (HBPU) can be prepared via a click chemistry reaction. Various compositions of HBPU-functionalized MWCNTs were synthesized from reactions of azide moiety-containing HBPU with alkyne-functionalized MWCNTs. The HBPU-functionalized MWCNTs were characterized morphologically using transmission electron microscopy and field emission scanning electron microscopy and chemically using Fourier transform infrared spectrometry, Raman spectroscopy, and X-ray photoelectron spectroscopy. The functionalized MWCNTs exhibited excellent dispersion in the HBPU matrix, and as a result, superior mechanical and strong antibacterial properties were obtained. The antimicrobial properties were examined by use of gram-negative bacteria Escherichia coli (E. coli). Consequently the click coupled bonding of MWCNTs with HBPU was very efficient for regulating the composite properties and achieving high performance materials.     

Synthesis and antimicrobial activity of quaternary ammonium-functionalized POSS (Q-POSS) and polysiloxane coatings containing Q-POSS

An array of quaternary ammonium-functionalized POSS (Q-POSS) compounds were synthesized and their antimicrobial properties toward the Gram-negative bacterium, Escherichia coli, and the Gram-positive bacterium, Staphylococcus aureus, determined in aqueous solution. Using Q-POSS compositions that exhibited broad spectrum antimicrobial activity in solution, the utility of the Q-POSS compounds as an antimicrobial additive for polysiloxane coatings was determined. The results of the investigation showed that Q-POSSs possessing a relatively low extent of quaternization and longer alkyl chain lengths provided the highest antimicrobial activity in solution. For polysiloxane coatings containing Q-POSS molecules as an antimicrobial additive, coating surface energy, surface morphology, and antimicrobial properties were found to be strongly dependent on Q-POSS composition. Coatings based on Q-POSSs possessing the lowest extent of quaternization displayed antimicrobial activity while analogous coatings produced using Q-POSSs possessing the highest extent of quaternization showed no antimicrobial activity. The lack of antimicrobial activity exhibited by coatings possessing Q-POSSs with a relatively high extent of quaternization was attributed to agglomeration of Q-POSS molecules through the formation of intermolecular interactions involving the quaternary ammonium moieties. Agglomeration would be expected to reduce diffusivity and inhibit interaction of the Q-POSS molecules with microbial cells.     

Poly(ethylene) glycol-modified,amphiphilic, siloxane–polyurethane coatings and their performance as fouling-release surfaces

Amphiphilic siloxane–polyurethane (AmSiPU) coatings were prepared using a series of polyisocyanate prepolymers modified with polydimethyl siloxane (PDMS) and poly(ethylene glycol) (PEG). Fouling-release performance of the AmSiPU coatings was evaluated through laboratory biological assays using several representative marine organisms. First, polyisocyanate prepolymers with compositional variation in PDMS and PEG were synthesized and characterized using Fourier transform infrared spectroscopy (FTIR) and isocyanate titrations. Then, the prepolymers were incorporated into coatings. Surface wettability of the coatings was evaluated using contact angle and surface energy measurements. Coatings’ surfaces were also characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). ATR-FTIR and XPS experiments revealed that both PDMS and PEG moieties were present on the surface suggesting amphiphilic character. AFM phase images show microphase separation. AmSiPU coatings show excellent fouling-release performance toward bacteria (Cellulophaga lytica), the diatoms (Navicula incerta), and the green algae (Ulva linza), demonstrating comparable or superior performance to many commercial amphiphilic fouling-release coatings. Despite the incorporation of hydrophilic PEG, AmSiPU coatings show good macrofouling release which is often challenging with amphiphilic coating systems. AmSiPU coatings are a nontoxic and tough fouling-release solution with comparable performance to benchmarks in the fouling-release coatings market.     

Silver- and Zinc-Decorated Polyurethane Ionomers with Tunable Hard/Soft Phase Segregation

Segmented polyurethane ionomers find prominent applications in the biomedical field since they can combine the good mechanical and biostability properties of polyurethanes (PUs) with the strong hydrophilicity features of ionomers. In this work, PU ionomers were prepared from a carboxylated diol, poly(tetrahydrofuran) (soft phase) and a small library of diisocyanates (hard phase), either aliphatic or aromatic. The synthesized PUs were characterized to investigate the effect of ionic groups and the nature of diisocyanate upon the structure–property relationship. Results showed how the polymer hard/soft phase segregation was affected by both the concentration of ionic groups and the type of diisocyanate. Specifically, PUs obtained with aliphatic diisocyanates possessed a hard/soft phase segregation stronger than PUs with aromatic diisocyanates, as well as greater bulk and surface hydrophilicity. In contrast, a higher content of ionic groups per polymer repeat unit promoted phase mixing. The neutralization of polymer ionic groups with silver or zinc further increased the hard/soft phase segregation and provided polymers with antimicrobial properties. In particular, the Zinc/PU hybrid systems possessed activity only against the Gram-positive Staphylococcus epidermidis while Silver/PU systems were active also against the Gram-negative Pseudomonas aeruginosa. The herein-obtained polyurethanes could find promising applications as antimicrobial coatings for different kinds of surfaces including medical devices, fabric for wound dressings and other textiles.     

The effect of formulation variables on fouling-release performance of stratified siloxane–polyurethane coatings

The effects of formulation variables, such as type of polyol, solvent type and solvent content, and coating application method, on the surface properties of siloxane–polyurethane fouling-release coatings were explored. Fouling-release coatings allow the easy removal of marine organisms from a ship’s hull via the application of a shear force to the surface. Self-stratified siloxane–polyurethane coatings are a new approach to a tough fouling-release coating system. Combinatorial High Throughput Experimentation was employed to formulate and characterize 24 different siloxane–polyurethane coatings applied using drawdown and drop-casting methods. The resulting coatings were tested for surface energy using contact angle measurements. The fouling-release performance of the coatings was tested using a number of diverse marine organisms including bacteria (Halomonas pacifica and Cytophaga lytica), sporelings (young plants) of the green macroalga (Ulva linza), diatom ((microalga) Navicula incerta), and barnacle (Amphibalanus amphitrite). The performance of the majority of the coatings was found to be better than the silicone standards, Intersleek^® and Silastic^® T2. An increase in solvent content in the formulations increased the surface roughness of the coatings. Coatings made with polycaprolactone polyol appeared to be somewhat rougher compared to coatings made with the acrylic polyol. The adhesion strength of sporelings of Ulva increased with an increase in solvent content and increase in surface roughness. The adhesion strengths of Ulva sporelings, C. lytica, and N. incerta were independent of application method (cast or drawdown) in contrast to H. pacifica adhesion, which was dependent on the application method.     

Antimicrobial functionalization of poly(ethylene terephthalate) fabrics with waterborne N‐halamine epoxides

A water dispersible terpolymer of [2‐(methacryloyloxy)ethyl]trimethylammonium chloride, glycidyl methacrylate and hydantoinyl acrylamide was synthesized and coated on poly(ethylene terephthalate) fabrics through a pad‐dry‐cure procedure. The coatings were rendered biocidal upon exposure to dilute household bleach solution. The halogenated fabrics exhibited great antimicrobial functionality with about six logs inactivation of S. aureus and E. coli O157:H7 within only two min of contact time. Moreover, the coatings were found to be very stable against repeated washings and UVA light exposure. It was shown that [2‐(methacryloyloxy)ethyl]trimethylammonium monomer is very useful in preparing waterborne N‐halamines which can impart rechargeable, effective, and stable antimicrobial coatings to poly(ethylene terephthalate) fabrics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43088.     

Synthesis,characterization and self-crosslinking of glycidyl carbamate functional resins

Multifunctional glycidyl carbamate functional resins were synthesized, characterized, and self-crosslinked coatings were prepared and characterized. Coatings based on glycidyl carbamate (GC) functional oligomers are attractive because they combine polyurethane properties with epoxide reactivity. The glycidyl carbamate functional resins were synthesized via reactions of the biuret adduct and isocyanurate trimer of hexamethylene diisocyanate (HDI) with glycidol. Resins were characterized using gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy and ¹³C NMR spectroscopy. Coatings were prepared to study the self-crosslinking reaction without additional hardener. Self-crosslinked coatings had an excellent combination of solvent resistance, good hardness and high impact resistance. The glycidyl carbamate resin from the biuret isocyanate adduct (BGC) was found to be more reactive during cure than glycidyl carbamate from the isocyanurate isocyanate trimer (IGC) as determined by hardness, solvent resistance, and T_g measurements. Thermogravimetric analysis (TGA) of the resins did not show thermal decomposition below 250 °C.     

Novel tailor-made diols for polyurethane coatings using a combination of controlled radical polymerization,ring opening polymerization,and click chemistry

Novel dihydroxy functional 3-arm star polymers were synthesized using a combination of atom transfer radical polymerization, ring opening polymerization, and click chemistry. The diols were characterized using gel permeation chromatography, Fourier transform infrared spectroscopy, and ¹H NMR spectroscopy. The diols were incorporated into polyurethane coatings, which were characterized using differential scanning calorimetry, thermogravimetric analysis, pendulum hardness, water contact angle, and methyl ethyl ketone double rubs. The coatings showed an increase in the water contact angle values as the percentage of the polystyrene-based diol was increased. Similarly, the coatings with the poly(tert-butyl acrylate)-based diols showed a decrease in the glass transition temperature values with an increase in the diol content. It is expected that the use of controlled radical polymerization would allow for the synthesis of novel tailor-made functional polymers to achieve tunable coatings properties.     

Investigation of the effect of ZnO nanoparticles on the thermomechanical and microbial properties of hyperbranched polyurethane‐urea hybrid composites

Hybrid coatings of hyperbranched polyurethane‐urea (HBPUU) containing ZnO nanoparticles were prepared by mixing the hyperbranched polyurethane with the nanoparticles. The films were stored at room temperature and laboratory humidity conditions for one week to yield completely cured hybrid films. The ZnO nanoparticles were found to be well dispersed in the polymer up to 3 wt%. The structure–property relationship of various HBPUU–ZnO hybrid coatings was analysed using a Fourier transform infrared peak deconvolution technique with a Gaussian curve‐fitting procedure, while their viscoelastic, thermomechanical and surface morphology were studied using X‐ray diffraction, dynamic mechanical thermal analysis, thermogravimetric analysis, a universal testing machine, scanning electron microscopy, atomic force microscopy and contact angle instruments. The thermal stability and mechanical properties of the hybrid composite films improved with increasing ZnO content, which was believed to be due to thermal insulation in the presence of nanoparticles. Water contact angle data suggested that the hydrophobic character of the hybrid composites increased with increasing nanoparticle concentration. The antimicrobial property of the HBPUU–ZnO hybrid coatings was studied using the disc diffusion method. HBPUU–ZnO hybrid coatings showed good antimicrobial properties compared to HBPUU. Copyright © 2012 Society of Chemical Industry     

Polymer/silica nanohybrids by means of tetraethoxysilane sol–gel condensation onto waterborne polyurethane particles

Stable waterborne polyurethane/silica hybrid dispersions were obtained by sol–gel reaction of tetraethoxysilane added to previously synthesized waterborne polyurethane nanodispersions. Two series of polyurethane/silica nanostructures with different silica contents were synthesized using pure polyurethane particles and polyurethane particles previously functionalized with (3-aminopropyl)triethoxysilane (APTES) as colloidal templates. The optimum experimental conditions for tetraethoxysilane sol–gel reaction (T = 75 °C and semi batch polymerization conditions) leading to the formation of silica/polyurethane aqueous nanodispersions were established. The presence of silica was confirmed using TGA, FTIR, ²⁹Si NMR and TEM. TEM images showed an excellent final dispersion of the silica nanoparticles in the polymer matrix when silane functionalized polyurethane nanoparticles were used.     

Biocidal polymers active by contact. II. Biological evaluation of polyurethane coatings with pendant quaternary ammonium salts

Films of polyurethane were prepared by reaction of hydroxytelechelic polybutadienes carrying covalently bound quaternary ammonium salts with an aliphatic triisocyanate. These coatings exhibited high biocidal activity against Gram-positive and Gram-negative bacteria, yeasts, and moulds. It was found that many parameters controlled the bioactivity such as the time of contact between films and bacteria, the [NCO]/[OH] ratio used to prepare the cured polyurethane, the concentration of quaternary ammonium salts in the coating, and the length of the alkyl chain from C₈ to C₁₆ linked to the quaternary nitrogen atom. A secondary phenomenon of diffusion only observed with the shorter alkyl chains (C₈ and C₁₀) was shown to be due to synthesis residues. After these water-soluble impurities are eliminated, the biocidal activity remains excellent: then it is due only to a contact polymer bacteria. © 1993 John Wiley & Sons, Inc.     

Damage resistance of SiC and Si3N4 coatings with control of microstructure and thickness

We investigated the contact damage and indentation stress–strain behavior of silicon carbide (SiC) coatings and binary coatings consisting of SiC and silicon nitride (Si₃N₄), synthesized on graphite substrates with porosities of 10 and 13% by a solid–vapor reaction, in order to determine the coatings’ damage resistance. The coating thickness was affected by the porosity of the substrate. The coatings on the substrate with 13% porosity showed a graded interface structure below the top dense layer. The SiC coatings were thicker than the SiC/Si₃N₄ composite coatings. The SiC coatings made the substrates hard, and SiC-coated substrates exhibited higher stress–strain curves than the substrates alone, but the SiC/Si₃N₄ composite coatings appeared unaffected. The coating thickness played an important role in limiting the effect of damage. The hardness values of the SiC coatings were higher than those of the substrates and the SiC/Si₃N₄ coatings. These corresponded well with the indentation stress–strain curves. The values of each coating showed saturated points depending on the applied load. This indicated that the substrate itself influenced the damage resistance of the coatings because of the layered structure of a harder coating with a softer substrate. The coatings enhanced contact damage and transmitted the damage to the substrates at a high load of P = 2000 N. Both coatings showed an extensive subsurface damage, independent of the porosity of the substrate. In cyclic indentation tests, the contact diameters linearly increased with the number of cycles and depended on the porosity of the substrate, showing smaller contact diameters by coating the substrate.     

UV-curable nano-silver containing polyurethane based organic–inorganic hybrid coatings

The preparation of nano-silver containing polyurethane based UV-curable organic–inorganic hybrid coatings that have antibacterial activity is presented in this paper. Trimethoxysilane end-capped bis[(4-β-hydroxyethoxy)phenyl] methyl phosphine oxide urethane was synthesized as a coupling agent and used to improve the compatibility between the organic and inorganic phases of the hybrid coating. Due to its strong antibacterial activity, silver nanoparticles were prepared and added to the nanocomposite formulations. The relationships between the amount of coupling agent and the final coating properties were investigated. The hybrid coatings presented good thermal stability. Tests for abrasion, hardness, gloss, and adhesion of the coatings were also performed. The morphological investigation was performed by SEM to determine the size of the silver nanoparticles. The nano-silver containing coatings exhibited good antibacterial activity against E. coli and S. aureus.