Trimethoxysilyl Propyldimethyloctadecyl Ammonium Chloride Research Articles

Exploring surface silanols in mesoporous Na-LTA zeolite to enhance its catalytic activity in knoevenagel condensation by grafting amino groups

Mesoporous Na-LTA zeolite was synthesized using the surfactant templating method with the organosilane surfactant [3-(trimethoxysilyl)propyl] octadecyldimethylammonium chloride (TPOAC). The formation of mesopores not only improved the accessibility of the basic catalytic sites but also led to the formation of isolated external silanols. These silanols were used to anchor propylamine groups by reacting with 3-aminopropyltrimethoxysilane (APTMS). The incorporation of propylamine groups in the mesoporous Na-LTA improved its catalytic activity in the Knoevenagel condensation reaction by 40 % due to the presence of extra basic catalytic sites from amino groups. The combination of mesopore generation and functionalization is an efficient strategy for enhancing the performance of Na-LTA zeolite in this reaction.

Efficient and stable perovskite solar cells: The effect of octadecyl ammonium compound side-chain

The extreme vulnerability of hybrid perovskite solar cells (PSCs) to moisture greatly limits the realization of their full potential. Here, we propose an efficient strategy to reinforce the efficiency and the ambient stability of PSCs via employing a series of octadecyl ammonium salts (OASs): octadecyl trimethyl ammonium chloride (OTAC), octadecyl dimethyl benzyl ammonium chloride (ODBAC), and 3-(trimethoxysilyl)propyl octadecyldimethyl ammonium chloride (TOAC), as passivating agents. Among these OASs, TOAC bearing a trimethoxysilane (Si-O-CH3) side chain group most efficiently promoted the efficiency along with the high-humidity stability of PSC devices. TOAC significantly passivated the defects, assisted better energy-level alignment and facilitated charge carrier transport in the devices. The TOAC-passivated PSCs exhibited an increase in the average PCE from 16.62 ± 0.56 % to 20.06 ± 0.68 % with a substantially enhanced fill factor of 80.10 ± 1.82 %. Furthermore, the unencapsulated TOAC-passivated PSCs preserved 90 % of their performance after storage in ambient conditions (25–30 ℃, 50–70 % relative humidity) for 300 h. When no OAS passivator was introduced, the devices were losing more than 74 % of their starting PCE after 150 h. The Si-O-CH3 groups side-chained to the OAS molecules were capable of supporting superior protection to the PSC devices against the permeation of high-moisture. Thereupon, the application of multifunctional octadecyl ammonium salt molecules to passivate defects and tailor the interface energy-level alignment in PSCs offers an encouraging staging to upgrade the PV performance of PSCs.

Highly Permeable Polylactic Acid Membrane Grafted with Quaternary Ammonium Salt for Effective and Durable Water Disinfection.

Given the increasing usage of drinking water purifiers, highly permeable membranes with strong antimicrobial functions are desperately desirable for effective and durable water disinfection. Hereby, we prepared such antimicrobial membranes by chemical grafting of quaternary ammonium salt (QAS) molecules, 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride (TPMMC), onto air plasma pretreated biodegradable polylactic acid (PLA) substrates. The high chemical grafting density promoted very strong and positive zeta potential charge of the resulted PLA-QAS membrane, contributing to effective and broad-spectrum antimicrobial efficiencies (>99.99%) against different microbes, including fungi and conventional and drug-resistant bacteria. The solid grafting of QAS molecules produced a durable antimicrobial performance of the PLA-QAS membrane. In addition, the pleated filter (0.45 m2) of PLA-QAS membrane showed outstanding bacteria rejection properties (>99.99%) and excellent washing durability (up to 20 m3 water) even at very high water filtration rates (up to 4 L/min). The disinfection mechanism was clarified that negatively charged bacteria could be rapidly adsorbed to positively charged PLA-QAS spinnings, followed by devastating cell membrane damage to bacterial debris, leaving a clean environment without significant biofilm and biofouling formation.

Catalytic Decomposition of H2O2 for NO Oxidation‐Removal over Hierarchical Fe‐ZSM‐5: Effect of Ethanol on Zeolite Performance

AbstractHierarchical Fe‐ZSM‐5 zeolite catalysts hydrothermally prepared using tetrapropylammonium hydroxide (TPAOH) and [3‐(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) as micropore structure‐directing agent and meso‐porogen, respectively, were investigated for oxidation‐removal of NO via catalytic decomposition of gas‐phase H2O2 into hydroxyl free radicals (⋅OH). The effects of ethanol in synthesis gel on the structure, porosity, Fe species state, and catalytic performance of zeolite catalysts were explored. And the function mechanism of ethanol was speculated. Appropriate ethanol dosage in synthesis gel probably stabilized TPOAC micelles during MFI crystallization, facilitated mesopores integration in zeolite crystals, benefited oxygen vacancy formation, accelerated ⋅OH radicals generation, and thereby enhanced NO oxidation‐removal efficiency. The hierarchical Fe‐ZSM‐5 prepared with ethanol/H2O ratio of 1 in synthesis gel displayed an excellent catalytic activity with the optimal NO conversion up to 35.9 % enhancement compared to the microporous Fe‐ZSM‐5. The SO2 resistance and ⋅OH scavenger test during catalytic reaction, as well as the reaction condition influence on the catalytic performance of hierarchical Fe‐ZSM‐5 were explored, and then the oxidation‐removal mechanism of NO over hierarchical Fe‐ZSM‐5 was preliminarily proposed.

Effective regulation of Ga active species in mesoporous ZSM-5 for catalytic upgrading of coal pyrolysis volatiles

Quality improvement of pyrolysis tar with yield increasing of high value-added components is highly desired for coal utilization. Herein, Ga-impregnated mesoporous ZSM-5 (Ga/MZ5) directed by organosilane surfactant of [3-(trimethoxysilyl) propyl] octadecyldimethylammonium chloride (TPOAC) is used as a catalyst for the catalytic upgrading of coal pyrolysis volatiles. Effective regulation by reduction and reduction/reoxidation promotes a secondary dispersion of gallium species from external surface deposition to micropore permeation. The comprehensive evaluation of catalytic upgrading performance indicates that the designedly regulated gallium species (mainly Ga+, GaH2+ and GaO+), feasible balance of Brønsted and Lewis active sites and mesopore diffusion superiority effectively contribute the yield increasing of both light-fraction (MLF/MTar) and target products of BTEXN (benzene, toluene, ethylbenzene, xylene and naphthalene). The optimal catalyst of Ga/MZ5_R/O exhibited the highest value of MLF/MTar (88 %) and highest yield of BTEXN (31.84 mg.g−1), which are 173 and 589 % higher than non-catalytic single pyrolysis and 133 and 280 % higher than those over the conventional Ga-impregnated ZSM-5 (Ga/Z5). Moreover, the possible reaction networks towards high value-added products of BTEXN based on the positive conversion of polycyclic aromatic hydrocarbons (PAHs), phenols, and other oxygen-containing compounds (abbreviated as PPO) is further proposed.

Evaluating pore characteristics and acid site locations in hierarchical SAPO-11 by catalytic model reactions

Hierarchical SAPO-11 molecular sieves were synthesized with three different mesopore structure directing agents (meso-SDAs): cetyltrimethylammonium bromide (CTAB), polyvinyl alcohol (PVA) and [3-(trimethoxysilyl) propyl] dimethyloctadecylammonium chloride (TPOAC). Two model reactions, methanol-to-hydrocarbons (MTH) and the Beckmann rearrangement (BMR) of cyclohexanone oxime, were employed to evaluate the pore topology and acid site locations of the hydrothermally synthesized hierarchical SAPO-11s. Initially, the modified porosity of the hierarchical SAPO-11s was thoroughly probed by employing a set of general characterization methods and by comparing the results to the conventional microporous C-SAPO-11. The nitrogen physisorption results revealed that CTAB-11 had a uniform distribution of mesopores centered at 2.8 nm, whereas the presence of mesopores in PVA-11 could not be convincingly resolved through conventional methods. Instead, the pore topology of PVA-11 was determined by utilizing model reactions, where the shape selective MTH model reaction revealed that the sample had mesopores present through an increased production of large products compared to the conventional C-SAPO-11. Additionally, the MTH model reaction showed that while PVA shifted the location of the Brønsted acid sites (BAS) towards the mesopores, CTAB did not affect the BAS location of SAPO-11. Finally, the BMR model reaction elucidated the excellent intrapore connectivity of the hierarchical SAPO-11s through an increased lifetime compared to the conventional C-SAPO-11. • Hierarchical SAPO-11 (H-S11) with interconnected micro- and mesopores was synthesized with CTAB and PVA as meso-SDAs. • Model reactions are crucial for understanding the topological differences between microporous SAPO-11 (µ-S11) and H-S11. • CTAB significantly alters the textural properties of the resulting H-S11, while PVA shows similar properties to µ-S11. • PVA directs formation of Brønsted acid sites to mesopores, whereas CTAB forms silanols in mesopores. • Superior lifetime for the isomerization of cyclohexanone oxime revealed the intraconnected pore topology for H-S11.

Improved accessibility of Na-LTA zeolite catalytic sites for the Knoevenagel condensation reaction

The use of zeolites in basic catalysis is limited when large molecules are involved, such as in the manufacture of fine chemicals, due to difficulty in accessing the micropores of the catalyst. A solution to this problem is to synthesize zeolites containing mesopores that improve the accessibility of the active sites. This work investigates the synthesis of zeolites 4A according to a bottom-up method employing the organosilane surfactant [3-(trimethoxysilyl) propyl] octadecyldimethylammonium chloride (TPOAC), at different concentrations in the synthesis mixture (TPOAC/Al2O3 = 0–0.09), to produce mesopores. The zeolites were evaluated in the Knoevenagel condensation reaction, which is strongly influenced by the accessibility of the catalytic sites, due to the large sizes of the molecules involved. Zeolites 4A with mesopores, showing higher external surface areas, were formed in the presence of TPOAC at the different concentrations tested. Higher conversions were achieved using the zeolites with mesopores, compared to conventional zeolite 4A, due to improved access of the reactant molecules to the catalytic sites. In addition, the reaction catalyzed by the zeolite with mesopores had lower activation energy, compared to use of the conventional zeolite 4A.

Versatile nanoadsorbents based on magnetic mesostructured silica nanoparticles with tailored surface properties for organic pollutants removal

This paper addresses the development of new magnetic silica-based nanoadsorbents and evaluates their potential application in the removal of contaminants of emerging concern (CECs), polyaromatic hydrocarbons (PAHs) and aliphatic hydrocarbons. For this purpose, magnetic iron oxide nanoparticles were covered with a hybrid shell of silica and 3-(trimethoxysilyl)propyl-octadecyldimethyl-ammonium chloride (TPODAC) as structure directing agent. The as-prepared hybrid material (MMST) was further modified with trimethoxyphenylsilane, obtaining a phenyl-functionalized nanoadsorbent (MMST-Ph). Both materials were thoroughly characterized with diverse physicochemical techniques, and batch sorption tests with single-contaminant and with mixtures of contaminants were performed. MMST-Ph proved to be more efficient for the adsorption of PAHs and aliphatic hydrocarbons. The presence of TPODAC and phenyl moieties anchored on the mesostructured silica frameworks resulted to be a key factor to obtain high PAHs uptakes from aqueous media. In the case of CECs, ibuprofen (IBU), diclofenac (DCF) and carbamazepine (CBZ) were tested. These experiments demonstrated that even though MMST possesses better adsorption capacities of CECs, MMST-Ph achieved high IBU and DCF uptakes. Regeneration and reuse experiments showed that MMST-Ph can be reused in eight cycles without losing the adsorption capacity of anthracene. In the case of MMST, there was a 42% drop in the adsorption capacity of ibuprofen in the second cycle, whereas in the next seven cycles the adsorption capacity remained constant.The promising results obtained in this work strengthen the potential application of surface-modified magnetic silica nanoparticles for the removal of different types of organic pollutants from waters.

Evaluation of surfactant templates for one-pot hydrothermal synthesis of hierarchical SAPO-5

Abstract Hierarchical SAPO-5 molecular sieves were synthesized with three different mesopore structure-directing agents (meso-SDAs) (cetyltrimethylammonium bromide (CTAB), myristyltrimethylammonium bromide (MTMAB) and [3-(trimethoxysilyl)propyl] dimethyloctadecylammonium chloride (TPOAC)) based on a soft-template hydrothermal synthesis procedure. To investigate the modified porosity of the hierarchical SAPO-5s, they were characterized thoroughly with the results being compared to the conventional microporous SAPO-5. Nitrogen sorption measurements revealed considerable hysteresis loops for the hierarchical SAPO-5s as well as larger mesopore volumes (≥0.15 cm3 g-1) compared to the conventional SAPO-5 (0.05 cm3 g-1). The relative number of acid sites for each sample was calculated from FTIR adsorption data and was in the order of C-SAPO-5>H-CTAB>H-MTMAB>H-TPOAC. The hierarchical SAPO-5s had a significantly increased lifetime (>150 h) in the methanol to hydrocarbons (MTH) model reaction compared to the conventional SAPO-5 (

Contact-active antimicrobial graphene oxide electrodes by covalent grafting of alkoxysilane octadecyldimethyl (3-trimethoxysilylpropyl)-ammonium chloride (ODDMAC) for capacitive deionization disinfection

Alkoxysilane octadecyldimethyl (3-trimethoxysilylpropyl)-ammonium chloride (ODDMAC) functionalized graphene oxide (GO) has been used as contact-active electrodes for capacitive deionization disinfection (CDID) at a contaminant concentration of 104 CFU/mL. It was found that, at the voltage of 1.2 V, the disinfection efficiency of this hybrid electrode can reach 99.65% for Escherichia coli (E. Coli), 98.64% for Pseudomonas aeruginosa (P. aeruginosa) and 97.69% for Staphylococcus aureus (S. aureus), respectively. Besides, the possible effects of GO/ODDMAC precursor ratios and salt ion on the disinfection performance of CDID were also carefully investigated. The CDID presented in this work has a promising prospect in terms of the practical water disinfection.

Organosilane surfactant-directed synthesis of nanosheet-assembled SAPO-34 zeolites with improved MTO catalytic performance

Hierarchical SAPO-34 zeolites with a special nanosheet-assembled morphology were hydrothermally synthesized under dynamic condition by using the commercial quaternary ammonium-type organosilane surfactant [3-(trimethoxysilyl) propyl] octadecyldimethyl-ammonium chloride (TPOAC) for the mesoscopic aggregation and tetraethylammonium hydroxide as the micropore structure-directing agent. The growth evolution during the crystallization process and governing factors including TPOAC content and dynamic hydrothermal condition in the synthesis were discussed in detail, and the possible nucleation and growth process were proposed as well. With a systematic structure characterization by XRD, FTIR, N2 adsorption–desorption, ICP, SEM, TEM, NH3-TPD and pyridine-adsorbed IR measurements, the nanosheet-assembled SAPO-34 (NA-SP34) prepared under the optimized synthesis condition presented the pure phase of CHA framework, high degree of crystallinity, interconnected hierarchical meso-/microporosity and relatively weak acidity comparing with the conventional microporous SAPO-34 (CM-SP34) with micron size and the nanosheet-like SAPO-34 (NL-SP34) synthesized in the absence of TPOAC. Moreover, the catalytic performances evaluated by the methanol-to-olefin reaction indicated that the optimal NA-SP34 catalyst presented remarkable improvements of not only much longer catalytic lifetime (300 min) and slower coke formation rate (0.24 mg g−1 min−1) but also higher ethylene and propylene selectivity (81.93%) comparing with those (95 min, 0.55 mg g−1 min−1 and 80.75%, respectively) of CM-SP34, which can be attributed to the integrated balance of well-remained microporosity, considerable mesoporosity and suitable weak acidity.

Non-leaching, broad-spectrum antibacterial poly (ε-caprolactone)/gelatin-QAS nanofiberous membranes for wound dressing

5-20 wt% trimethoxysilylpropyl octadecyldimethyl ammonium chloride (QAS) was used to modify Poly (ε-caprolactone) (PCL)-gelatin hybrid to fabricate non-leaching antibacterial nanofiber membranes (PG-Q) by electrospinning. The results from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the QAS leaded to phase separation between the QAS and PCL. Hydrophilic test demonstrated that the PG-Q nanofiber membranes had hydrophobic surface, which was help for peeling off the dressing from the wound. Additionally, the physical and chemical cross-linking between the QAS/PCL and QAS/gelatin were confirmed by Fourier transform infrared (FTIR), which were good for long lasting antibacterial effect. The PG-Q membranes also showed excellent cell-biocompatibility. Furthermore, compared with pure PCL nanofiber membrane, the PG-Q nanofiber membranes, especially PG-Q15 (QAS: 15 wt%) and PG-Q20 (QAS: 20 wt%), showed a considerable increase in the bacteriostatic rate of S. aureus and P. aeruginosa (more than 99% after 12 h). Therefore, electrospinning non-leaching antibacterial nanofiber membranes could be an optimal choice for antibacterial wound dressing.

Long-acting and broad-spectrum antimicrobial electrospun poly (ε-caprolactone)/gelatin micro/nanofibers for wound dressing

Trimethoxysilylpropyl octadecyldimethyl ammonium chloride (QAS), which forms facile bonds with hydroxyl groups, acts asa cationic antibacterial agent. In this work, QAS was introduced into a polycaprolactone (PCL)/gelatin hybrid in increasing concentrations to fabricate a long-acting and broad-spectrum antimicrobial micro/nanofiber membrane as a novel wound dressing. The physical interactions and chemical bonding between QAS/PCL and QAS/gelatin were demonstrated by infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS. Measured water contact angle between the PCL-gelatin/QAS (PG-Q) nanofiber membranes suggested a hydrophobic surface, which has been shown to aid in removal of wound dressings. The mechanical strength of the membranes was sufficient to meet the clinical requirements. Furthermore, the 15% QAS (PG-Q15) and 20% QAS (PG-Q20) formulated nanofiber membranes showed a considerable increase in their bacteriostatic activity towards Staphylococcus aureus (gram-positive) and Pseudomonas aeruginosa (gram-negative) bacteria, suggesting a broad-spectrum bactericidal effect by the PG-Q membranes. The PG-Q membranes with various QAS formulations demonstrated little cytotoxicity. Therefore, the long-acting and broad-spectrum antimicrobial electrospun PG-Q micro/nanofibers membrane demonstrate potential efficacy asan antibacterial wound dressing.

One-Step Synthesis of Functionalized ZSM-12 Zeolite as a Hybrid Basic Catalyst

Preparation of ZSM-12 zeolite (MTW structure) functionalized with the organosilane surfactant [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) was performed in a single synthesis step employing hydrothermal crystallization. Investigation was made of the effects of Si/Al and TPOAC/SiO2 ratios on crystallinity, morphology, and catalytic activity. The MTW structure without the presence of TPOAC was obtained using Si/Al ratios ranging from 50 to 120, with values smaller than 50 favoring crystallization of the BEA phase, and values greater than 120 leading to the formation of cristobalite, a crystalline silica phase. For syntheses performed in the presence of TPOAC, an increase in its amount from 3 to 6 % enabled formation of the pure MTW structure, at all Si/Al ratios. The addition of TPOAC led to significant changes in the morphology and hydrophobicity of the zeolite particles. The effect of functionalization with TPOAC on the catalytic performance of the zeolites was evaluated using the Knoevenagel condensation between butyraldehyde and ethyl cyanoacetate as a model reaction. It was found that the presence of TPOAC in the ZSM-12 zeolite substantially increased the catalytic activity. Evaluation was also made of the type of solvent used in the reaction, and high activities were obtained in the presence of polar protic solvents.

Direct synthesis of hierarchical ferrierite nanosheet assemblies via an organosilane template approach and determination of their catalytic activity

Hierarchical ferrierite (FER) nanosheet assemblies with a ball-shaped morphology were prepared via a direct hydrothermal synthesis by using an organosilane surfactant, 3-(trimethoxysilyl) propyl octadecyl dimethyl ammonium chloride (TPOAC) as structure directing agent (SDA). The prepared nanosheet assemblies not only have a different morphology (micro-spherical nanosheet assemblies) but also a higher hierarchy factor (HF) (0.11) compared with that obtained in the case of conventional FER (plate-like products with HF value of 0.03). The enhanced HF of the FER nanosheet assemblies corresponds to an increase in mesopore surface area as they preserve the microporous zeolitic features in terms of crystallinity and acidity. This results in an improvement of the catalytic activities (82% and 14% conversion efficiency in the cases of the FER nanosheet and the conventional FER, respectively) for the benzylation of toluene with benzyl chloride. We demonstrate a simple way to create hierarchical FER nanosheet assemblies with a 2D pore system by a direct synthesis via an organosilane-SDA approach. This is complementary to the nanosheet design on other types of zeolites besides MFI and FAU nanosheets and opens up the catalytic applications involving bulky molecules like in the case of benzylation.

Antibacterial cellulose membrane via one-step covalent immobilization of ammonium/amine groups

This work describes a direct covalent linking of quaternary ammonium salts (QAS) and aminoalkyl groups onto regenerated cellulose (RC) membrane surface to prepare contact active antibacterial membrane materials. The membranes were prepared via alkoxysilane polycondensation reaction with three silane coupling agents, including trimethoxysilylpropyl trimethyl ammonium chloride (QASC0), trimethoxysilylpropyl octadecyldimethyl ammonium chloride (QASC18) and 3-aminopropyltrimethoxysilane (APS). FTIR, XPS, FESEM and AFM were used to characterize the chemical composition and surface morphology of the resulted RC-QASC0, RC-QASC18 and RC-NH2 membranes. Membrane surface charge properties were measured by the streaming potential method. Static water contact angle (WCA) and permeation flux were measured to investigate surface wettability and membrane permeability. Escherichia coli and Staphylococcus aureus were used as model bacteria to evaluate the antibacterial properties of membranes. The bacterial cell viability on membrane surfaces was evaluated by the dynamic shake flask test and the bacterial anti-adhesion properties were evaluated by confocal laser scanning microscopy (CLSM) measurements following the immersion test. RC-QASC18 and RC-NH2 membranes show strong antibacterial and bacteria anti-adhesion properties. Both membranes have a bacteria killing ratio over 99.5%. The stability study shows that the antibacterial property of modified membranes is robust in a wide range of pH and temperature conditions.

Effect of Different Templates on the Synthesis of Mesoporous Sodalite

Sodalite is a type of zeolite having ultramicropore size and high thermal stability with strong basic sites. However, sodalite has several drawbacks in the catalyst application due to its smallest pore size (2.8 Å) and low surface area. To overcome these disadvantages, microporous sodalite can be modified to have mesoporous structure but maintain its active sites suitable for catalyst applications. This study was focused on the synthesis of mesoporous sodalite using various organic templates as structure directing molecules. A hierarchical mesoporous sodalite has been synthesized hydrothermally at 150°C for crystallization by using several mesotemplate and fumed silica as a silica source. The synthesized samples were characterized using XRD, FTIR, BET surface area, and FESEM. XRD and FTIR showed that all templates being used in the synthesis produced sodalite phase. The sodalite synthesized using organosilane (trimethoxysilyl-propyldimethyloctadecyl ammonium chloride) and mixture of tetrapropyl ammonium hydroxide and cetyltrimethylammonium bromide with ratio of 1 : 1 showed mesoporosity as proven by higher BET surface area as compared to microporous sodalite with different pore structure as proven by pore distribution.

Surface Modification for Cotton Fiber and its Antimicrobial Characteristics

Quaternary ammonium compounds, Couple, Cotton fiber, Antibacterial activity. Abstract. a gemini-type quaternary ammonium compound with a hydroxyl group in their spacer chain, 4,5-bis(dodecyl dimethyl ammonium bromide)-1-pentanol (called as DAP12), was immobilized on the surface of cotton fiber by using a silane coupler, tetraethoxysilane and a novel antibacterial cotton fiber (called as CF12) was prepared. Antibacterial characteristics of CF12 were investigated comparatively with [3-(trimethoxysilyl) propyl] octadecyldimethylammonium chloride(TPOAC), a mono-type quaternary ammonium salt. CF12 had excellent antibacterial characteristics in the wide range of environmental pH and temperature, which is not weakened even if 30 times repetitive use. The experimental results indicated also that CF12 has higher antimicrobial activity than TPOAC immobilized on the surface of cotton fiber against a broad range of microorganisms, and average inhibition ratio against 15 strains of gram-negative, gram-positive bacteria and yeasts is 99.0% at 30 °C and pH 6.0.

Enzymatic Degradation of Model Cellulose Film Pre-Treated with Antimicrobial Agent

Enzymatic degradation of model cellulose films pre-treated with antimicrobial agent, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (TMPAC) was investigated. AFM topographical imaging was used to assess the surface morphology, roughness, and thickness of the dried and hydrated model cellulose film. The kinetics of the model cellulose film in the hydrated state, the adsorption of TMPAC onto the film followed by desorption given by an enzyme extracted from Trichoderma Viride were studied by in situ null ellipsometry. The results show that the adsorption of TMPAC onto model cellulose film slows down the rate of degradation, as confirmed by a slower decrease in the film mass and by different behaviour of the thickness of the film pre-treated with antimicrobial agent in comparison with pure model cellulose film.

Nonleaching Antimicrobial Films Prepared from Surface-Modified Microfibrillated Cellulose

We have prepared potentially permanent antimicrobial films based on surface-modified microfibrillated cellulose (MFC). MFC, obtained by disintegration of bleached softwood sulfite pulp in a homogenizer, was grafted with the quaternary ammonium compound octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride (ODDMAC) by a simple adsorption-curing process. Films prepared from the ODDMAC-modified MFC were characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) and tested for antibacterial activity against the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. The films showed substantial antibacterial capacity even at very low concentrations of antimicrobial agent immobilized on the surface. A zone of inhibition test demonstrated that no ODDMAC diffused into the surroundings, verifying that the films were indeed of the nonleaching type.