Plasma Induced Graft Polymerization of Three Hydrophilic Monomers on Nylon 6,6 Fabrics for Enhancing Antistatic Property

In this study, three hydrophilic monomers; 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-hydroxyethyl methacrylate, diallyldimethylammonium chloride (DADMAC) were selected and their performance as an antistatic finish on nylon 6,6 fabrics was investigated. A non-thermal, high density atmospheric pressure plasma was used to graft polymerize the monomers on nylon 6,6 fabrics. Fabrics were first treated with solutions of monomer in water, air dried and then treated with helium plasma to graft polymerize the monomer on the fiber surface. Surface resistivity values were measured before and after soxhlet extraction with water. Results showed that the DADMAC monomer provided better antistatic properties to fabrics. Further studies with DADMAC monomer were made; effects of plasma post exposure time, plasma pre-exposure time, plasma power, concentration of the monomer and existence of a crosslinker were investigated. Higher plasma power, higher concentration of the monomer and longer post exposure times all gave better antistatic properties to the nylon 6,6 fabrics. Acid dye staining, UV–Vis and FT-IR measurements were conducted and results confirmed a grafted poly-DADMAC layer on the fabric surface.     

Surface nanostructuring of kevlar fibers by atmospheric pressure plasma‐induced graft polymerization for multifunctional protective clothing

Atmospheric plasma‐induced graft polymerization was employed successfully to generate free radical on the surface of Kevlar® (poly‐(p‐phenylene terephthalamide or PPTA), and to initiate and control graft polymerization of cationic antimicrobial precursors diallyldimethylammonium chloride (DADMAC) or 3‐(trimethoxysilyl)propyl‐dimethyloctadecyl ammonium chloride (TMS) onto the fabric surface, which eliminates the need for separate processes that may involve thermal energy or UV irradiation. It was demonstrated that when the radiofrequency of the plasma power was 400 W, the radical density generated on the surface was 10¹⁵ to 10¹⁶ radicals cm^?2, which were enough to generate a poly‐DADMAC or poly‐TMS with surface charge of at least 2 × 10¹⁷ N⁺/cm², which is the minimum threshold for an effective cationic biocidal surface. In both cases, the grafted polymers were characterized and confirmed using SEM, FTIR, and XPS. The antimicrobial activity was measured using the AATCC Test Method 100, which showed that at least 3‐log reduction of bacteria colonies was achieved in the case of grafted poly‐DADMAC or grafted poly‐TMS on Kevlar®. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Antibacterial cotton fabric prepared by a “grafting to” strategy using a QAC copolymer

Quaternary ammonium compounds (QACs) have outstanding antimicrobial effect, but covalent immobilization of plentiful QAC onto cotton fiber surface to realize a durable function remains a challenge. Herein, a quaternary ammonium monomer, [2-(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) was co-polymerized with methyl acrylate (MA) to prepare an antibacterial copolymer, poly(DMC-co-MA). To graft the copolymer with an improved grafting efficiency, cotton fabric was treated using carboxymethyl chitosan (CMC) to establish an amino-functionalized fiber surface first. This treatment allows the amidation reactions between the amino groups and the pendant ester groups in the poly(DMC-co-MA) to take place, achieving a durable anionic polymer coating onto the fiber surfaces with remarkably antibacterial effect. Characterization results indicated that when DMC/MA monomer ratio was 100:1, the resulting copolymer endows the modified cotton fabric with antibacterial capability that inactivates all Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Even after 50 laundering cycles, more than 98.0% of the antibacterial rate could still be retained. Moreover, the wearing comfort properties such as softness, water absorption and air permeability of the finishing cotton fabrics have been insignificantly changed by comparing to the untreated cotton fabric.

     

Synthesis and Characterization of Poly(Diallyldimethylammonium Chloride-g-Acrylamide)

Graft copolymers of poly(diallyldimethylammonium chloride), (poly-DADMAC), with acrylamide were synthesized using a ceric salt/nitric acid initiation system. The effects of concentration of initiator, monomer, and substrates were studied. Copolymers were characterized by viscometry and size-exclusion chromatography. The highest molecular weight ( M _w ) of graft copolymer obtained was 1.70 × 10⁶. The compositions of copolymers are dependent upon the ratios of the concentration of monomer to the concentration of substrate. The highest content of DADMAC monomer unit in the copolymer was 33 wt%.     

Analysis of plasma polymerization of allylamine by FTIR

The plasma polymerization of allylamine in an inductively coupled rf plasma reactor is analyzed by Fourier transform infrared spectroscopy. Comparison of the infrared spectra of the as-received monomer and the plasma polymerized film reveals a conversion of the primary amine in the monomer (? CH₂? NH₂) to an imine (? CH?NH) and a nitrile (C?N). Plasma polymerization of ethylenediamine yields the same results, suggesting that this polymerization scheme may be typical of primary amines. Increasing the plasma power seems to increase the proportion of nitrile groups in relation to the imine groups. The infrared spectra of the vapor phase polymerized monomer was similar to that of the substrate-grafted allylamine film implying a similar structure. Aging of this vapor phase polymer at 120°C for 1 h in vacuum and at 295°C for 15 min in an oxygen free environment reveals nitrile group reaction similar to that observed in polyacrylonitrile. Thermogravimetric analyses of the vapor phase polymers in a nitrogen atmosphere at 20°C/min demonstrated the thermal stability, with the polymer produced at a plasma power level of 50 W retaining 20% of its weight at 1000°C. This was better than the stability shown by the polymer produced at 150 W and is attributed to the ease of nitrile group polymerization in the former.     

Functionalization of Cotton by In-Situ Reaction of Styrene in Atmospheric Pressure Plasma Zone

Cotton fabric was treated using styrene/helium glow plasma at the atmospheric pressure. After the treatment, the substrate was found to turn into a highly hydrophobic material showing water drop disappearance time of 60?min and water contact angle of 133°. The treatment was found to be durable even after vigorous washing. The effect of various parameters, such as discharge voltage and frequency, on fragmentation of styrene inside plasma zone was investigated using optical emission spectroscopy and GC?CMS. The types of fragments formed in the plasma zone were correlated with the hydrophobicity of the substrate. The chemical nature of surface of the substrate was analyzed using SEM and Raman spectroscopy to elucidate the possible mechanism of plasma modification.     

An improved method for the durability of the flame retardant PA66 fabric

This paper describes an attempt in order to improve the durability of the flame retardant polyamide 66 (PA66) fabric prepared by the reaction of surface photografting with acrylamide (AM) under UV irradiation. In this study, N,N′-methylene bisacrylamide (MBAAm) combined with acrylamide has been used as a photosensitive monomer during flame retardant finishing of the PA66 fabric sample. “Durable efficiency” has been introduced to evaluate the durability of AM/MBAAm-g-PA66 fabric after 50 times washing with the 0.5 % commercial grade detergent solution. The result indicates that durable efficiency reaches its maximal value of 94.5 % when the MBAAm concentration is 5.0 mass%. The effect of MBAAm on the flame retardancy, thermal stability and tensile properties of the treated PA66 fabric has been investigated, respectively. And an interesting phenomenon shows that although MBAAm could improve the thermal stability of the treated fabric significantly at high temperature, it could have a negative effect on the flame retardancy and tensile properties of the fabric sample when its concentration is high. Its possible mechanism has been discussed here.     

Preparation of thermosensitive membranes by radiation grafting of acrylic acid/N-isopropyl acrylamide binary mixture on PET fabric

Thermosensitive membranes were prepared by radiation-induced graft copolymerization of monomers on PET fabrics. A binary mixture of N-isopropyl acrylamide (NIPAAm) and acrylic acid (AA) was grafted on polyester fabric as a base material to introduce thermosensitive poly(N-isopropyl acrylamide) pendant chains having LCST slightly higher than 37 °C in the membrane. The influence of ferrous sulfate, radiation dose and monomer composition on the degree of grafting was studied. The structure of the grafted fabric was characterized by thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy. The thermosensitive nature of the fabric was monitored by swelling at different temperatures. The graft copolymerization of AA with NIPAAm enhanced the LCST of the resultant membrane to ∼37 °C. The moisture vapor transmission rate (MVTR) and air permeability of the fabric decreased slightly, may be due to the slight blocking of the fabric pores. The immobilization of tetracycline hydrochloride as the model drug and its release characteristics at different temperatures were monitored.     

Preparation of rechargeable biocidal polypropylene by reactive extrusion with diallylamino triazine

Biocidal polypropylene (PP) was prepared by using a reactive extrusion process, in which PP was grafted with an N-halamine precursor, 2, 4-diamino-6-diallylamino-1, 3, 5-triazine (NDAM). After chlorination the grated PP was converted to biocidal halamine structures. Effects of monomer and initiator concentration on grafting yield, thermal properties, and biocidal efficacy were studied. The Fourier transformed spectroscopy (FTIR) results and nitrogen analysis confirmed the graft polymerization on PP backbone during the reactive extrusion. The results also indicated that at low monomer concentration, increase in initiator concentration led to increase in PP chain scission and decrease in mixing torque, or polymer chain length. As the monomer concentration increases, grafted monomer content in the products showed a steady increase, indicating more grafting copolymerization in the system. The halogenated products exhibited potent antimicrobial properties against Escherichia coli, and the antimicrobial properties were durable and regenerable.     

Chemical graft polymerization of sulfobetaine monomer on polyurethane surface for reduction in platelet adhesion

Surface modification is an effective way to improve the hemocompatibility and remain bulk properties of biomaterials. Recently, polymer tailored with zwitterions was found having good blood compatibility. In this study, the zwitterionic monomer of sulfobetaine was graft polymerized onto polyurethane (PU) surface in a three-step heterogenous system through the vinyl bonds of acrylic acid (AA) or hydroxyethyl methacrylate (HEMA), which was immobilized with hexamethylene diisocyanate (HDI) beforehand. First, PU was activated with isocyanate groups using HDI as coupling agent. Second, AA or HEMA was introduced through reaction of AA or HEMA with NCO groups bonded on PU surface. Last, zwitterionic monomer of sulfobetain was graft polymerized with vinyl group of AA or HEMA using AIBN as polymerization initiator. The reaction process was monitored with ATR-IR spectra and XPS spectra. Variation of graft yield with temperature and monomer feed concentration was investigated and feasible conditions were optimized. The wettability of films was investigated by water contact angle measurement and water absorbance. Platelet adhesion experiment was conducted as a preliminary test to confirm the improved blood compatibility of PU. The number of platelets adhering to PU decreased greatly comparing with the originals after 1 and 3 h of contact with human plate-rich plasma (PRP).     

Radiation induced graft polymerization of a fluorinated acrylate onto fabric

A fluoride acrylate monomer, 1H,1H,2H,2H-nonafluorohexyl-1-acrylate (denoted as F4), was grafted onto cotton fabric through a simultaneous irradiation induced graft polymerization technique. The grafted cotton fabric (denoted as cotton–F4) is superhydrophobic (SCF) when the degree of grafting (DG) exceeded 10%. The morphology of the cotton fabric was unchanged. In addition, the mechanical properties of the cotton fabric and SCF samples were also studied. The results showed that the decrease in mechanical properties was less than 20%, indicating that the SCF retained good mechanical strength.     

Aqueous MADIX/RAFT polymerization of diallyldimethylammonium chloride: Extension to the synthesis of poly(DADMAC)‐based double hydrophilic block copolymers

Macromolecular design by interchange of xanthates/reversible addition fragmentation chain transfer polymerization (MADIX/RAFT) of diallyldimethylammonium chloride (DADMAC) using the hydrophobic O‐ethyl‐S‐(1‐methoxycarbonyl) ethyl dithiocarbonate MADIX/RAFT mediating agent, Rhodixan A1, was investigated. Attempts to obtain an efficient control of DADMAC polymerization in a water/ethanol mixture failed because of significant chain transfer to ethanol. The use of a water‐soluble Rhodixan A1‐terminated acrylamide oligomer as the MADIX/RAFT agent enabled the controlled polymerization of DADMAC in water at 50 °C using the cationic azo initiator V‐50. An excellent agreement was found between experimental and theoretical M_n values throughout polymerization and over a broad range of initial concentration of xanthate. Polydispersity indexes (PDIs) at the end of the polymerization were abnormally high for a process showing a linear increase of M_n with monomer conversion (1.8 < PDI < 2.0). This feature was explained by the measurement of a high transfer constant to xanthate (C_x = 18.8 ± 1.6) but a low interchange transfer constant (C_ex = 1.5). Nevertheless, poly(acrylamide)–poly(DADMAC) double hydrophilic block copolymers (DHBCs) of controlled M_n and composition could be successfully synthesized for the first time. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Radical Homo- and Copolymerization of Acrylamide and Ionic Monomers in Weak Magnetic Field

Summary: The synergy between magnetic field (MF) and electrostatic interactions on the kinetics of radical homopolymerization of acrylamide (AM), acrylic acid (AA), its ionized form acrylate (A⁻) and diallyldimethylammonium chloride (DADMAC), as well as AM/AA, AM/A⁻, DADMAC/AA, and DADMAC/AM copolymerizations was investigated. The application of MF during the polymerizations significantly increased the monomer consumption rate (Rp) of all monomers in homo and copolymerizations and the molar masses of polyAA and polyNaA. The molar mass of polyAM and the copolymer composition of any monomer combination remained unchanged by MF. The electrostatic interactions between ionic monomers and growing radicals dominate for the monomers and conditions studied here.     

DC plasma polymerization of hexamethyldisiloxane

Hexamethyldisiloxane (HMDS) was polymerized onto metallic and insulating substrates in a parallel-plate DC reactor. The limits of the DC reactor with respect to pressure and power were determined for deposition of PP-HMDS films. In all conditions ranging from 5 Pa/0.3 W to 100 Pa/50 W, solid films were deposited. No powders or oily films were obtained under any condition in this operating range. The films were polymeric in nature,i.e., they were neither carbon-like nor SiO _x -like films. The structures and crosslink densities of the plasma films dependend strongly on the deposition conditions. The highest deposition rates, up to 2 μm per minute (or0.3 mg/cm² min), were obtained at high power, pressure, and flow rate conditions. An efficiency ɛ is introduced, defined as the fraction of the monomer that is retained in the form of a polymer deposited on the substrate. Efficiencies as high as 25% could be obtained in certain conditions. Pulsing the discharge power increased the conversion efficiency markedly, but the effect depended strongly on the monomer used. In addition to HMDS, plasma polymers were also deposited from pyrrole in pulsed conditions for comparison. A method is described for depositing films on insulators from a DC glow discharge using two wire meshes held at a negative potential.     

Spectroscopic study on chemical structure of plasma-polymerized hexamethyldisiloxane

A plasma-polymerized material was produced from hexamethyldisiloxane vapor by a glow discharge polymerization technique. Spectroscopic interpretation of the chemical structure of the polymerized hexamethyldisiloxane was studied by spectroscopic means such as IR, XPS, and NMR. The plasma polymer was barely soluble in the usual organic solvents, although it contained a small amount of the monomer and its oligomers. The IR spectrum indicated that the polymer consisted of Si? CH₃, Si? O, Si? CH₂, and Si? H groups. The surface of the polymer was found to retain structural units similar to the monomer from the XPS measurement. On the other hand, the ¹³C and ²⁹Si high-resolution, solid-state NMR measurements revealed that the plasma polymer was highly crosslinked with a variety of conformations and a number of O atoms surrounding a Si atom. Results from the XPS and NMR spectra suggested that the bulk of the polymer was more oxidized than the surface layer; Si atom was preferentially oxidized. A hypothetical chemical structure was proposed for the polymerized hexamethyl-disiloxane.     

Gelation in the Copolymerization of Diallyldimethylammonium Chloride with Acrylamide

Diallyldimethylammonium chloride (DADMAC) was free-radical copolymerized with acrylamide (AA) in water at a total monomer concentration of 4 mol/L and 40°C with different monomer feed compositions. Gelation occurred only for 20/80 DADMAC/AA monomer feed although crosslinking was observed for all monomer feed compositions. The gel point was at 51% conversion, and the swelling ratios of the resulting gels were quite high, from 1400 to 700. Addition of 2‐propanol as a chain‐transfer reagent reduced crosslinking and prevented gelation. These results are mechanistically discussed in connection with the cyclopolymerizability of DADMAC, and significant allylic hydrogen abstraction by the growing polymer radical characteristic of allyl polymerization is proposed.     

Radiation synthesis of poly[(dimethylaminoethyl methacrylate)-co-(diallyl dimethyl ammonium chloride)] hydrogels and its application as a carrier for notoginsenoside delivery

Novel pH/temperature sensitive hydrogel was synthesized by radiation induced copolymerization and cross-linking of dimethylaminoethyl methacrylate (DMAEMA) and diallyldimethyl ammonium chloride (DADMAC). Reactivity ratio of DADMAC (r₁) and DMAEMA (r₂) was determined as 1.02 and 0.98, which means that poly(DMAEMA-co-DADMAC) is an azeotropic copolymer. Content of DADMAC, i.e., charge density of the hydrogel was found to influence their properties significantly. Compared with polyDMAEMA hydrogel, poly(DMAEMA-co-DADMAC) showed enhanced equilibrium degree of swelling (EDS). Low critical solution temperature (LCST) of the hydrogel increased with the charged density. Content of DADMAC had no effect on the pH dependence of the final gel. Aiming at its application as a carrier for Chinese herb extract delivery system, the embedment and pH/temperature dependence of controlled release were investigated using notoginsenoside as a model drug. The maximum embedment amount of notoginsenoside was obtained in a gel containing 3 mol.% DADMAC. The temperature dependence and pH dependence of notoginsenoside release followed the same trend as that of EDS, for instance, higher ratio of notoginsenoside release occurred at 25 °C and pH 1.7, at which higher EDS was obtained. By these means, the release of notoginsenoside can be controlled by adjusting the pH, ionic strength, temperature of solution as well as the composition and structure of the gel.     

Study and Optimization on graft polymerization under normal pressure and air atmospheric conditions,and its application to metal adsorbent

Radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto non-woven polyethylene (NWPE) fabric was achieved under normal pressure and air atmospheric conditions, without using unique apparatus such as glass ampoules or vacuum lines. To attain graft polymerization under normal pressure and air atmospheric conditions, the effects of the pre-irradiation dose, pre-irradiation atmosphere, pre-irradiation temperature, de-aeration of GMA-emulsion, grafting atmosphere in a reactor, and dissolved oxygen (DO) concentration in GMA-emulsion on the degree of grafting (Dg) were investigated in detail. It was found that the DO concentration had the strongest influence, the pre-irradiation dose, de-aeration of emulsion and grafting atmosphere had a relatively strong impact, and the pre-irradiation atmosphere and pre-irradiation temperature had the least effect on Dg. The optimum DO concentration before grafting was 2.0 mg/L or less. When a polyethylene bottle was used as a reactor instead of a glass ampoule, graft polymerization under normal pressure and air atmospheric conditions could be achieved under the following conditions; the pre-irradiation dose was more than 50 kGy, the volume ratio of GMA-emulsion to air was 50:1 or less, and the DO concentration in GMA-emulsion during grafting was below 2.0 mg/L. Under these grafting conditions, Dg was controlled within a range of up to 362%. The prepared GMA–grafted NWPE (GMA–g-NWPE) fabric was modified with a phosphoric acid to obtain an adsorbent for heavy metal ions. In the column-mode adsorption tests of Pb(II), the adsorption performance of the produced phosphorylated GMA–g-NWPE fabric (fibrous metal adsorbent) was not essentially dependent on the flow rate of the feed. The breakthrough points of 200, 500, and 1000 h^?1 in space velocity were 483, 477 and 462 bed volumes, and the breakthrough capacities of the three flow rates were 1.16, 1.15 and 1.16 mmol-Pb(II)/g-adsorbent.     

Radiation‐induced graft modification of knitted poly(ethylene terephthalate) fabric for collagen immobilization

Radiation‐induced graft co‐polymerization of methacrylic acid and N‐vinyl‐2‐pyrrolidone mixture from poly(ethylene terephthalate) knitted fabrics were conducted using a preirradiation method. The influence of the graft conditions, such as irradiation dose, reaction time, monomer concentration and temperature on the degree of grafting was determined. It was found that there is a limiting irradiation dose of 40 kGy above which the degree of grafting does not increase. An increase in the monomer concentration from 20 to 40% and an increase in temperature from 60 to 80°C gave a higher initial rate of grafting as well as higher equilibrium graft levels. The characterization of the fabric was carried out by attenuated total reflectance infrared spectroscopy (ATR‐IR), X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The grafted fabric surface, carrying negatively charged carboxylate ions, was shown to attract collagen, being positively charged to provide bioreceptive surfaces. Copyright © 2007 John Wiley & Sons, Ltd.     

Characterization of N-isopropyl acrylamide/acrylic acid grafted polypropylene nonwoven fabric developed by radiation-induced graft polymerization

Radiation-induced graft copolymerization of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) mixture was carried out on polypropylene nonwoven fabric to develop a thermosensitive material and has been found to affect the thermal and physical characteristics of fabric. The grafted fabrics with different monomer ratios were characterized by thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), contact angle and atomic force microscopy (AFM). Results of FTIR clearly indicated that poly(acrylic acid) and poly(N-isopropyl acrylamide) were successfully grafted onto the membrane surface. TGA results showed that the thermal stability of PP fabric increased after grafting of NIPAAm/AA. The crystallinity values from DSC and XRD were found to decrease with increase in degree of grafting because of the addition of grafted chains within the noncrystalline region. The decrease in contact angles of the grafted fabric with an increase of the degree of grafting shows that PNIPAAm/PAA exists as the hydrophilic component. The increase in surface roughness after grafting was observed by AFM.