Surface modification of poly(ethylene terephthalate) film by coating with poly(ethylene glycol)‐grafted polystyrene

The poly(ethylene glycol) (PEG)‐grafted styrene (St) copolymer, which was formed as a nanosphere, was used as an agent to modify the surface of poly(ethylene terephthalate) (PET) film. The graft copolymer was dissolved into chloroform and coated onto the PET film by dip–coating method. The coated amount depends on the content ratios of PEG and St, the solution concentration, and the coating cycles. The graft copolymers having a low molecular weight of PEG‐ or St‐rich content was fairly stable on washing in sodium dodecyl sulfate (SDS) aqueous solution. It was confirmed that the PET surface easily altered its surface property by the coating of the graft copolymers. The contact angles of the films coated with the graft copolymers were very high (ca. 105–120°). The coated film has good antistatic electric property, which agreed with PEG content. The best condition of coating is a one‐cycle coating of 1% (w/v) graft copolymer solution. The coated surface had water‐repellency and antistatic electric property at the same time. The graft copolymer consisted of a PEG macromonomer; St was successfully coated onto PET surfaces, and the desirable properties of both of PEG macromonomer and PSt were exhibited as a novel function of the coated PE film. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1524–1530, 1999     

Surface modification of linear low‐density polyethylene film by amphiphilic graft copolymers based on poly(higher α‐olefin)‐graft‐poly(ethylene glycol)

In this article, a series of amphiphilic graft copolymers, namely poly(higher α‐olefin‐co‐para‐methylstyrene)‐graft‐poly(ethylene glycol), and poly(higher α‐olefin‐co‐acrylic acid)‐graft‐poly(ethylene glycol) was used as modifying agent to increase the wettability of the surface of linear low‐density polyethylene (LLDPE) film. The wettability of the surface of LLDPE film could be increased effectively by spin coating of the amphiphilic graft copolymers onto the surface of LLDPE film. The higher the content of poly(ethylene glycol) (PEG) segments, the lower the water contact angle was. The water contact angle of modified LLDPE films was reduced as low as 25°. However, the adhesion between the amphiphilic graft copolymer and LLDPE film was poor. To solve this problem, the modified LLDPE films coated by the amphiphilic graft copolymers were annealed at 110° for 12 h. During the period of annealing, heating made polymer chain move and rearrange quickly. When the film was cooled down, the alkyl group of higher α‐olefin units and LLDPE began to entangle and crystallize. Driven by crystallization, the PEG segments rearranged and enriched in the interface between the amphiphilic graft copolymer and air. By this surface modification method, the amphiphilic graft copolymer was fixed on the surface of LLDPE film. And the water contact angle was further reduced as low as 14.8°. The experimental results of this article demonstrate the potential pathway to provide an effective and durable anti‐fog LLDPE film. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Graft copolymers of lignin as hydrophobic agents for plastic (wood‐filled) composites

Poly[lignin‐g‐(1‐phenylethylene)] graft copolymers synthesized by free‐radical, graft copolymerization on lignin and verified by fractionation, infrared spectroscopy, and solubility change possess macromolecular surface activity as indicated by their capacity to form stable emulsions between incompatible fluid phases, to adhesively bond to wood surfaces, and to change the contact angle of water on coated wood. The surface activity of the copolymer changes with its composition. As the weight percent lignin in the copolymerization reaction product increases beyond 20 wt %, the amount of the emulsion phase formed in a water–benzene mixture decreases. Maple wood flour could be solvent‐coated with a copolymer and both coated and uncoated maple flour could be extruded through a stranding plate into a wood‐filled composite with polystyrene. Physical property tests show that composite control samples are about 3% stiffer and less deformable than are the copolymer composites when dry and about 5 or more percent more deformable than are the copolymer composites when wet, showing that the copolymer coating increased the wet strength. The copolymer samples are always denser than are the controls. Copolymer coating on wood filler decreases the swelling in the composite, the partial molar volume of the imbibed water, and the dimensional change in the solid. These effects cause increase in the density of the copolymer composite upon imbibition of water. Coating the wood component of the composite with a copolymer creates a hydrophobic barrier that produces a decrease in water imbibition into the composite, which will not disappear in 20 or more years of water immersion. Expansion in water is highly dependent on the direction of extrusion. The length expands about 1%, the width expands about five times as much, and the thickness expands over 10 times as much as does the length. This differential expansion may be due to the 22% reduction in the width and a 71% reduction in the thickness of the melt as it passes through the die and the alignment of the long axis of the fiber with the direction of flow through the die. The reaction product is a thermoplastic solid stable below 200°C and thermoformable at between 150 and 180°C. Products which contain between 10 and 50 wt % lignin are heterogeneous solids. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1266–1276, 2003     

Graft copolymers of wood pulp and 1-phenylethene. I. Generality of synthesis and proof of copolymerization

A method of grafting lignin-containing materials is now known that allows 1-phenylethylene (styrene, [100-42-5]) graft copolymers of a lignin source to be quantitatively made. The grafting reaction is a solution polymerization often run in aprotic, polar, organic solvents. Grafting changes solubility and surface properties of the lignin-containing material. The lignin-containing materials grafted are unbleached wood pulps produced by chemical, thermal, and mechanical pulping. Grafting wood pulp produces a wood-reinforced, thermoplastic composite. © 1993 John Wiley & Sons, Inc.     

Wetting of AlN and TiC by Liquid Ag and Liquid Cu

The wetting of AlN and TiC by liquid Ag and liquid Cu was investigated by the sessile drop technique at 10⁻⁶ torr or less. An empirical relation was established between the cosine of the contact angle and the temperature or surface tension of the liquid drop. The critical surface tension for spreading and its physical significance are discussed. A method for estimating the surface energies of ceramics is proposed. The surface tension of TiC is estimated to be 1242±158 dynes/cm and that of AlN 990±110 dynes/cm. The surface tension of liquid Ag followed the equation γ _Lv (Ag) (dynes/cm) = 1092–0.14T (°C) and that of liquid Cu γ _LV (Cu) (dynes/cm) = 1462–0.27T (°C).     

Surface tension and contact angle of herbicide solutions affected by surfactants

Contact angle and surface tension were measured for distilled and hard water solutions of adjuvants, Ortho X-77, Span-20, Sterox-NJ. Surfactant-WK, Triton B-1956, Triton X-114, Tween-20, and Sun Oil 11E. The same parameters were measured for suspensions of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and ametryne [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine] with and without each adjuvant. All adjuvants reduced surface tension and contact angle of distilled water; Surfactant-WK was most effective and Tween-20 was least effective. Increasing concentration of surfactants from 0 to 0.1% (v/v) gave progressive reduction in surface tension and contact angle while higher concentrations, 0.1 to 2.0% (v/v), had no further effect. Surfactant-WK at 0.1% (v/v) in distilled water reduced the surfact tension from 72.8 dynes/cm to 27 dynes/cm and contact angle from 110° to 41°. An additional increase in Surfactant-WK concentration from 0.1% (v/v) to 2% (v/v) did not further reduce surface tension and contact angle. Sun Oil 11E was identical in behavior except that it was less effective than the surfactants. Water hardness up to 1,000 ppm as Ca ions did not affect surface tension and contact angle in surfactant solutions. An aqueous solution of atrazine had a higher surface tension and contact angle than ametryne in the absence of surfactants. However, these differences were not observed when surfactants were added to either herbicide.     

Wetting properties of homopolymers and copolymers of pentafluorostyrene and methylacrylate and homopolymer blends

Polypentafluorostyrene (PPFS), polymethylacrylate (PMA), and poly(pentafluorostyrene-co-methylacrylate), poly(PFS-co-MA) were prepared and the wetting characteristics of polymer blends of PPFS and PMA were compared with that of poly(PFS-co-MA) via contact angle measurements. The critical surface tension of polypentafluorostyrene was found to be 22.6 dyne/cm, which is comparable to the value reported for polytrifluoroethylene (22 dyne/cm). The critical surface tension of poly(PFS-co-MA) is not linearly related to its composition. The polymer blends of PPFS and PMA exhibit significant surface enrichment of the fluoropolymer. The harmonic-mean method¹ was employed to determine surface tensions of these polymers and many known polymers. It is found that the method produces useful surface tension data provided the contact angle values are derived from testing liquids of dissimilar polarity.     

Critical Surface Tension for Spreading in the Systems (Al-Mg)/Graphite and (Cu-O)/Sapphire

According to Zisman and co-workers, in organic systems the cosine of the contact angle of a sessile drop increases with the decreasing surface tension of the drop at room temperature. The applicability of the Zisman relation to liquid metal-ceramic systems is discussed using the systems (Al-Mg)/graphite and (Cu-O)/sapphire. Also discussed is the significance of the critical surface tension for spreading, γ_c, in the systems where the surface tension of the liquid is greater than that of the solid substrate; γ_c is 230 dynes/cm for graphite at 720°C and 440 dynes/cm for sapphire at 1230°C.     

Functional biohybrid materials synthesized via surface-initiated MADIX/RAFT polymerization from renewable natural wood fiber: Grafting of polymer as non leaching preservative

Crude wood fibers represent a wide class of renewable resources. The surface modification of such materials via covalent grafting of polymer offers new surface properties with non-leaching coating. The grafting of the polymer chains was achieved by surface-initiated controlled radical polymerization through a grafted xanthate chain transfer agent. Macromolecular design via interchange of xanthate (MADIX) technique was chosen to graft poly(vinyl acetate), polystyrene, poly(n-butyl acrylate) and poly(4-vinylbenzyl chloride)-polystyrene amphiphilic cationic copolymers. Water contact angle measurements highlighted the hydrophobization of the wood fiber surface with a nanoscaled polymer monolayer indicating the appropriate coverage of the fiber. X-ray photoelectron spectroscopy showed the successful grafting of the polymer after drastic washing procedure. The quaternization of the grafted polystyrene-co-poly(4-vinyl benzyl chloride) copolymers with tertiary amine allows the introduction of biocide quaternary ammonium functions while preserving the hydrophobic character of the modified wood fiber when introducing a long alkyl chain in the statistical copolymer. Finally, the cationic copolymer was subjected to Coniophora Puteana to evaluate its propensity to limit the fungi expansion.     

Effect on Wettability of FEP Teflon Surface Morphology

Wettability of FEP Teflon® (a perfluorinated ethylene-propylene copolymer) is vastly improved by heterogeneous nucleation and crystallization in contact with gold, a high surface free energy substrate. The critical surface tension of wetting (γ_e) increases from 18.8 dynes/cm to 40.4 dynes/cm. We compute that this rise in γ_e results from a 20 percent increase in the surface density of gold-nucleated FEP Teflon®. The increase in critical surface tension from 18.8 dynes/cm to 20.6 dynes/cm, for as received FEP Teflon which had been crosslinked by helium in a glow discharge (CASING technique), suggests an increase of the surface density with crosslinking. The critical surface tension of the gold-nucleated FEP Teflon® is sharply decreased from 40.4 dynes/cm to 22.0 dynes/cm by short exposure to the CASING treatment in helium. The results of ATR infrared spectroscopy show that in the surface region of the polymer there are no chemical changes such as the presence of unsaturated groups or the introduction of polar groups by oxidation. We conclude from this study that wettability of the polymer surface is affected by the surface morphology.     

Effect on Wettability of FEP Teflon Surface Morphology

Wettability of FEP Teflon® (a perfluorinated ethylene-propylene copolymer) is vastly improved by heterogeneous nucleation and crystallization in contact with gold, a high surface free energy substrate. The critical surface tension of wetting (γ_e) increases from 18.8 dynes/cm to 40.4 dynes/cm. We compute that this rise in γ_e results from a 20 percent increase in the surface density of gold-nucleated FEP Teflon®. The increase in critical surface tension from 18.8 dynes/cm to 20.6 dynes/cm, for as received FEP Teflon which had been crosslinked by helium in a glow discharge (CASING technique), suggests an increase of the surface density with crosslinking. The critical surface tension of the gold-nucleated FEP Teflon® is sharply decreased from 40.4 dynes/cm to 22.0 dynes/cm by short exposure to the CASING treatment in helium. The results of ATR infrared spectroscopy show that in the surface region of the polymer there are no chemical changes such as the presence of unsaturated groups or the introduction of polar groups by oxidation. We conclude from this study that wettability of the polymer surface is affected by the surface morphology.     

PAA、PLiAA和PNaAA涂膜结晶度对其表面性能的影响

采用辊涂的方式将聚丙烯酸（PAA）、聚丙烯酸锂（PLiAA）和聚丙烯酸钠（PNaAA）溶液涂覆在铝箔上，通过控制不同的烘干时间和温度以获得不同结晶度的涂膜。用x-射线衍射测定聚丙烯酸、聚丙烯酸锂和聚丙烯酸钠涂膜的表面结晶度，实验测定了涂膜的表面张力和水在涂膜表面的铺展速度常数。讨论了表面结晶度、表面张力、水铺展速度常数与涂膜表面亲水性之间的关系，结果表明具有高表面张力和结晶度的涂膜有利于亲水性的提高。     

Wetting of Ceramics by Liquid Aluminum

The wettability of AlN, TiB₂, TiN, and TiC by liquid aluminum was investigated by the sessile drop technique at 2×10^-7 torr or less. The contact angle decreased linearly with increasing temperature in all cases. Variation of the contact angle with temperature is correlated with the surface tension of the drop, and the Zisman-type relation is established. The critical surface tensions (Rγ_c) of AlN, TiB₂, TiN, and TiC are 664, 700, 713, and 725 dynes/cm, respectively. These values are correlated with the melting point of the ceramics. The Zisman relation is discussed and applied to calculation of the work of adhesion. The surface tension of liquid aluminum varies linearly with temperature: γ_Lv (dynes/cm) = 948–0.202 T (°K).     

Synthesis and Identification of Graft Copolymers of Wood Pulp and 4-Methyl-2-oxy-3-oxopent-4-ene

A set of graft copolymers of wood pulp and 4-methyl-2-oxy-3-oxopent-4-ene has been synthesized. The graft reaction is a free radical polymerization coinitiated by calcium chloride, hydrogen peroxide on wood pulp in dimethylsulfoxide at 30°C. The wood pulps used in this research are unbleached products produced by chemical, thermal and mechanical pulping. All of them contain 25 to 29 weight percent lignin. Separation of the grafted wood pulp from homopoly(1-methyl-1-(2-oxy-1-oxopropyl)ethylene) formed during the reaction was done by benzene extraction. The results show that after the reaction, virtually all the wood pulps have a weight increase and, for very high yield sodium bisulfite pulp, a weight increase of up to 92.7% of the original weight of pulp was obtained. The Fourier transform infrared spectra of the benzene unextr-actable fractions provide strong proof of grafting.

The grafted wood pulp is a surface-modified pulp. Grafting has changed the surface properties of the starting wood pulp from hydrophilic to hydrophobic. The importance of this change is that the grafted wood pulp has potential use as a reinforcing material without use of coupling agents in many hydrophobic polymer matrixes.

The reaction products contain homopoly(1-methyl-1-(2-oxy-1-oxopropyl)ethylene) and uniformly dispersed grafted wood pulp. Under ordinary thermal compression conditions, thermoplastic composite objects can be made directly from the reaction products which contain up to 56 weight percent wood pulp.     

Performance of organic nanoparticle coatings for hydrophobization of hardwood surfaces

The protection of wood surfaces against water is a primary requirement to enhance their life-time and durability. In this article, a hydrophobic surface modification of selected hardwood surfaces (including high-density (HD) and low-density (LD) samples) is presented, by coating them with waterborne imidized nanoparticles under pure conditions or with vegetable oil. The performance of both nanoparticle coatings relative to noncoated and oil-coated samples was evaluated by water contact angles, microscopy, and optical profilometry. The pure nanoparticle coatings often increase the hydrophobicity, but they do not yet form a fully protective layer due to their porous structure after drying. The nanoparticle coatings with vegetable oil form a continuous layer with a maximum contact angle of 118°. The coating formation highly depends on the wood density (and resulting surface porosity), resulting in spreading of the aqueous dispersion on HD wood and penetration on LD wood. A thin continuous nanoparticle coating with incorporated vegetable oil provides highest contact angles, as the roughness of the original wood fibers remains visible in the surface profile.     

Effect of the length of branches on the critical surface tension of poly(n-alkyl methacrylates) and copolymers of stearyl methacrylate with methacrylonitrile

Critical surface tension values γ_c were measured for poly(n-alkyl methacrylates) and copolymers of stearyl methacrylate with methacrylonitrile. Surface tension values γ_L of n-alkyl methacrylate increase with increasing side chain length: γ_L = 23.2 dynes/cm for methyl methacrylate to 33.2 dynes/cm for stearyl methacrylate, but γ_c values of poly(n-alkyl methacrylate) decrease with increasing side chain length: γ_c = 36.3 dynes/cm for poly(methyl methacrylate) to 20.8 dynes/cm for poly(stearyl methacrylate). The decrease in γ_c is attributed to a tighter packing of the alkyl chain with a greater concentration of the pendent ? CH₃ group at the air/solid interface. Values of γ_c of copolymers hardly depended on the methacrylonitrile content in copolymers and did not satisfy the equation γ_c = N₁γ_c1 + N₂γ_c2 proposed by Lee. The difference in γ_c values for casting, annealing, and quenching films of poly(stearyl methacrylate) and the surface structure of copolymers were discussed using electron microscopy and measurement of melting point, heat of melting, and γ_c.     

Surface modification of polymethyl methacrylate by graft copolymers

Summary Graft copolymers composed of poly(methyl methacrylate) branches and different backbones of poly(fluoroalkyl acrylate(FA)-co-methyl methacrylate(MMA)), poly (hydroxyethyl methacrylate(HEMA)-co-MMA), and poly(FA-co-HEMA) were prepared by macromonomer technique to study their application as a surface modifier for PMMA films. Contact angle of water droplet on PMMA film specimens containing various amounts of these graft copolymers cast on glass slides from THF solution was found to change considerably with the graft copolymer concentration, depending on their backbone component. And there was considerable difference in contact angle between air and glass side of the film surfaces. These results were considered in terms of the surface accumulation of graft copolymers during the solvent evaporation.     

Combination of atom transfer radical polymerization and click chemistry toward cellulose-rosin derived UV-absorbent copolymers

UV absorption coating is an important function material, which can protect the substrates from photoaging. In this work, a class of sustainable UV-absorbent copolymers derived from ethyl cellulose (EC), fatty acid and rosin were prepared by a combination of atom transfer radical polymerization (ATRP) and click chemistry. To fulfill this strategy, the pendant azides were first attached onto the backbone of EC. Then, ATRP was applied to fabricate well-defined poly(lauryl methacrylate) (PLMA) bearing terminal alkynes. Finally, click chemistry between the pendant azides in EC and the alkynes in PLMA as well as in rosin esters (DAPE), was performed to achieve the cellulose-rosin graft copolymers (EC-(g-DAPE)-g-PLMA) with UV absorption property. The chemical structure of cellulose-rosin graft copolymers was confirmed by FTIR, ¹H NMR and GPC. Thermodynamic performance analysis indicated that these EC-rosin graft copolymers showed better thermal stability than EC. Due to the synergistic hydrophobic interaction of rosin and the hydrophobic lauryl groups in PLMA, these graft copolymers showed excellent hydrophobic property, and the static contact angles were all above 90°. In addition, all the EC-rosin graft copolymers showed outstanding and stable UV absorption capability, and maintained excellent UV absorption capability after continuous UV-irradiation for 1 h or being heated to 100 °C for 0.5 h, which had potential application in UV absorption materials.

     

Surface properties of graft copolymers surfactants: Behavior at the water/toluene interface

Poly(propylene oxide-b-ethylene oxide) (PPOPEO) surfactant has been used as a surface tension modifier. In this study, the graft copolymer made of poly(methyl methacrylate) (PMMA) main chain and PPOPEO graft chain behavior at water/toluene interface was observed. Interfacial tension measurements were conducted by dissolving the graft copolymer in toluene at a concentration range 1 wt % ?0.0003. The results confirmed the surfactant behavior of graft copolymers, which presented a PMMA/PPOPEO ratio dependence. The critical micellar concentration (CMC) was observed. Above the CMC, the graft copolymers tend to form a monomolecular association that depends upon copolymer molecular weight. © 1992 John Wiley & Sons, Inc.     

Glow-discharge-induced graft polymerization of acrylic acid onto poly[1-(trimethylsilyl)-1-propyne] film

Graft polymerization of acrylic acid onto poly[1-(trimethylsilyl)-1-propyne] [poly(TMSP)] film was examined. The water contact angle of poly(TMSP) film decreased remarkably from 90 to 15° by plasma treatment, which gradually increased up to 40° after several days. When the film exposed to a glow discharge was heated in an aqueous solution of acrylic acid at 80°C for 24 h, graft polymerization proceeded on the film surface, which was confirmed by ATR-IR and ESCA spectra. Graft polymerization effectively occurred above a threshold temperature (80°C). The water contact angle of the grafted film was about 30°, and did not change with time. In contrast, when a poly(TMSP) film exposed to UV irradiation was heated in an aqueous solution of acrylic acid, graft polymerization took place not only on the film surface but also inside the film.