Ethoxylated polyethylenimine gel‐coated on textile‐grade acrylic fiber. A thermally regenerable superfast sorbent for water desalination

With the transition towards the use of renewable feedstocks and renewable energy the use of bio-based molecules as feedstock and electro(catalytic) conversions gain in interest. Our target is to electrocatalytically convert starch to oxidized starch, which form a replacement for the currently used fossil based poly-acrylates. To develop efficient electrocatalysts for the oxidation process fundamental insights in catalyst property-performance relationships are essential. Since starch is a complex molecule we aim at getting these insights by using gradually more complex feedstocks, going from monomers to oligomers to polymers (e.g. from glucose to cellobiose to starch). Here we will show that for the electrocatalytic oxidation of glucose over Pt on carbon nanofibers (Pt/CNF), carboxylic acid groups on the carbon support have a positive influence on the catalytic activity, while hydroxyl groups have a negative influence. This is, also based on the influence of bulk pH effects, tentatively explained by local pH effects induced by surface oxygen groups.CNF supports were synthesized by chemical vapor deposition using CO/H2 and a Ni/SiO2 growth catalyst. After synthesis they were treated in sequential steps with 1M NaOH and 68% HNO3 to remove the growth catalyst and to introduce carboxylic acid and hydroxyl groups on the support (CNF-CA).1 Incipient wetness impregnation of Pt ammonium nitrate on CNF-CA followed by calcination was used to make the catalyst (5.0 wt.% Pt/CNF-CA). Pt/CNF-CA was heat treated at 300, 500 and 700 ˚C to gradually remove the support oxygen groups.1 The prepared electrocatalysts were drop-casted on a glassy carbon electrode to evaluate their performance for glucose oxidation by linear sweep voltammetry (LSV). The properties of the electrocatalysts were thoroughly analyzed by N2-physisorption, TEM, CO-stripping, TPD-MS, TGA, XPS, CV and titration.N2-physisorption, CO-stripping and TEM analysis showed that the physical properties of all electrocatalyst were similar: porosity (0.33 cm3.g-1), BET-surface area (182 m2.g-1), electrochemical surface area (120 m2.g-1) and the average Pt particle size (2.1 nm). The type and content of support oxygen groups of the electrocatalysts were assessed by CV, TPD-MS and TGA and revealed that the Pt/CNF-CA contains both carboxylic acid and hydroxyl groups on the carbon support surface. After treating the sample at 300 ˚C these carboxylic acid groups were removed and only hydroxyl groups were retained. After further increasing the treatment temperature the hydroxyl content decreased gradually. Therefore 4 different catalysts were prepared, i.e. with: carboxylic acid and high contents of hydroxyl groups (Pt/CNF-CA), and without carboxylic acid groups but with high, medium and low contents of hydroxyl groups (Pt/CNF-HO, Pt/CNF-MO and Pt/CNF-LO).The LSV measurements at pH 1 (Fig. 1A) show that Pt/CNF-CA has two oxidation peaks i.e., at 0.62 and 0.78V. This indicates that two oxidation processes occur, most likely the oxidative adsorption of glucose at 0.62 V and the oxidation of adsorbed glucose to δ-gluconolactone at 0.78 V.2 As the carboxylic acid groups were removed, going from Pt/CNF-CA to Pt/CNF-HO, the current densities decrease at 0.62 and 0.78 V. This decrease in current density indicates that the removal of carboxyl acid groups from the support results in a loss in catalytic activity. When the hydroxyl groups were removed, i.e., going from Pt/CNF-HO to Pt/CNF-MO to Pt/CNF-LO, the current density at 0.52 V increases, while the current density at 0.8 V remains unaffected. This increase in current density at 0.52 V represents an increase in catalytic activity for the oxidative adsorption of glucose for electrocatalysts with fewer hydroxyl groups on the support and might therefore affect the product distribution (currently under investigation). When the bulk pH of the electrolyte was increased from 1 to 3, it was found that Pt/CNF-CA is not affected by the pH, while at pH 3 the performance of all electrocatalysts that differ in hydroxyl content on the support (Pt/CNF-LO, P/CNF-MO and Pt/CNF-HO) resemble the performance of Pt/CNF-LO at pH 1. This is explained by the oxidation of the hydroxyl groups to carbonyl groups on the support resulting in the release of protons at pH 13 and thus a decrease in concentration of local hydroxyls in solution, which in turn hampers the electrocatalytic oxidation of glucose.The relation between the type and quantity of oxygen functionalities and current densities, shows that we can tune these oxygen functionalities to increase the catalytic activity, and simultaneously reduce the energy input (W=I*V) for the catalytic conversion. Our results also demonstrate how the type and presence or absence of support oxygen groups are related to the bulk pH, which in turn influences the catalytic performance of Pt towards the electrocatalytic oxidation of glucose.1)https://doi.org/10.1016/j.jcat.2004.05.0262)https://doi.org/10.1016/0022-0728(92)80454-C3)https://doi.org/10.1016/j.carbon.2013.07.082 Figure 1

We have differentiated the carboxylic acid groups present in the functionalized interface of “polyethylene carboxylic acid” (PE4O2H, a material prepared from low-density polyethylene film by reaction with aqueous chromic acid) into two subsets: those sufficiently close to the surface of the polymer to influence its wettability by water and those too deep to do so. This differentiation was accomplished by taking advantage of differences in rates of esterification of carboxylic acid groups in different regions of the functionalized interface and of differences in rates of hydrolysis of ester groups derived from them. The subset of functional groups influencing wettability comprises <30% of the total groups present in the functionalized interface and appears to be homogeneous in its chemical reactivity. The remaining groups (-70% of the total) do not directly influence wettability and appear to become less reactive with increasing depth in the polymer. The surface and subsurface carboxylic acid and ester moieties are both less reactive in hydrolysis and formation reactions than are these groups in organic molecules in solution. Reactivities of the interfacial functional groups depend on structure in ways having no analogy in reactions in solution. For example, the rate of base-catalyzed hydrolysis of esters present in the functionalized polymer interface is a strong function of the length of the alcohol component of the ester: n-octyl esters are more than 20000 times less reactive than methyl esters. We have also explored the acidity of the interfacial carboxylic acid groups using ATR-IR spectroscopy and contact angle measurements as probes. Both the local polarity of the environment of individual carboxylic acid groups and charge-charge interactions between carboxylate anions appear to be important in determining acidity. Comparisons of wettability of samples containing different proportions of carboxylic acid, carboxylate anion, and ester groups indicate that wettability is particularly sensitive to low concentrations of carboxylate anion. We hypothesize that this sensitivity reflects a limited ability of the functionalized interfacial region to reconstruct-perhaps only by small-amplitude rotations of its constituent carboxylate ions-in a way that minimizes its free energy by maximizing the number of these hydrophilic moieties in direct contact with the polar, aqueous liquid phase.

A commercial acrylic fiber with 92% (w/w) acrylonitrile content was partially hydrolyzed converting a fraction of the nitrile (CN) groups to carboxylic acid (COOH) groups, to coat the fiber with polyethylenimine (PEI) resin, which was then crosslinked with glutaraldehyde and further quaternized with ethyl chloroacetate to produce a novel strong‐base anionic exchanger in the form of fiber. Designated as PAN(QPEI.XG)(Cl−), the fibrous sorbent was compared with a commercial bead‐form resin Amberlite IRA‐458(Cl−) in respect of sorption capacity, selectivity, and kinetics for removal of silver thiosulfate complexes from aqueous solutions. Though the saturation level of [Ag(S2O3)2]3− on PAN(QPEI.XG)(Cl−) is considerably less than that on IRA‐458(Cl−), the gel‐coated fibrous sorbent exhibits, as compared to the bead‐form sorbent, a significantly higher sorption selectivity for the silver thiosulfate complex in the presence of excess of other anions such as S2O32−, SO42−, and Cl−, and a remarkably faster rate of both sorption and stripping. The initial uptake of the sorbate by the fibrous sorbent is nearly instantaneous, reaching up to ∼80% of the saturation capacity within 10 s, as compared to only ∼12% on the bead‐form sorbent. The high initial rate of uptake fits a shell‐core kinetic model for sorption on fiber of cylindrical geometry. With 4M HCl, the stripping of the sorbed silver complex from the fibrous sorbent is clean and nearly instantaneous, while, in contrast, a much slower rate of stripping on the bead‐form sorbent leads to its fouling due to a slow decomposition of the silver thiosulfate complex in the acidic medium. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2604–2613, 2006

Photo-polymerization behaviors of bisphenol-A epoxy diacrylate (EPA) and six kinds of EPA-derived resins containing different amounts of carboxylic acid, urethane, amide, and imide groups were studied by a photo differential scanning calorimetry. The dark polymerization was performed and pseudo-steady state assumption of growing radicals was made to obtain the kinetic constants for propagation, bimolecular termination, monomolecular termination, and the concentration of growing radicals of different resins as a function of extent of reaction. Compared with EPA, it was found that the rate of polymerization and kinetic constants of the six resins were relatively small because the mobility of reacting species in resins was restricted by carboxylic acid, urethane, amide, and imide groups. Finally, three different photo-initiators were used to initiate the polymerization, and their kinetic behaviors were compared. The effect of tertiary amine group of photo-initiator on the rate of polymerization of resins having carboxylic acid group and the initiator efficiency were discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

The effect of thermal treatment on the compositional structure of humic acids extracted from South African bituminous coal

Poly(dimethylsiloxane) copolymers containing a small fraction of carboxylic acid or Zn-carboxylate groups were prepared and compared regarding reversible gelation by hydrogen-bonding and ion-pair interaction. The polymers were synthesized by condensation of a t-butylcarboxylate functionalized dichlorosilane with an α,ω-dihydroxy-poly(dimethylsiloxane), followed by thermal cleavage of the ester bond. Neutralization of the resulting carboxylic acid substituents was achieved by addition of Zn (acac)2. Reversible crosslinking was investigated by step stress and oscillating shear experiments. The carboxylic acid containing poly(dimethylsiloxane) became rubberlike upon increasing the temperature and liquified again when it was brought back to room temperature. This observation has been explained tentatively by segregation of the carboxylic acid groups into polar domains at high temperatures [i.e., a behavior like it is observed for systems with a lower critical solution temperature (LCST)]. At ambient temperature, the carboxylic acid groups undergo hydrogen bonding to the Si–O–Si backbone. Clustering of the carboxylic acid groups occurs only as these hydrogen bonds break upon raising temperature. Moisture was found to have a strong influence on the reversal of the crosslinking. Addition of zinc acetylacetonate resulted in the formation of an elastic network already at ambient conditions consistent with the concept of ionomers which undergo reversible gelation by formation of ion-pair multiplets and clusters in the hydrophobic polymer matrix in particularly at low temperatures. At high temperature, both the carboxylic acid and the carboxylate sample exhibited a rather similar viscoelastic behavior consistent with a common structure where transient crosslinks are formed by clusters of the carboxylic acid and the carboxylate groups. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 485–495, 1999

Polyaromatic dyes, such as phthalocyanines and tetraazaporphyrins (TAPs), arrange with an edge-on orientation of the macrocycle in almost all Langmuir and Langmuir–Blodgett (LB) monolayers, especially when condensed at higher surface pressures. Presented here is a new amphiphilic TAP that contains eight terminal carboxylic acid groups attached to the macrocycle via decyl spacers, which forms stable Langmuir and LB monolayers with a flat-on orientation of the macrocycle. A spider-like molecular conformation is proposed based on the measured surface area per molecule and film thickness determined by ellipsometry and AFM. This conformation allows all eight terminal carboxylic acid and carboxylate groups to attach to the polar interface while the aromatic macrocycle sits on top of the orthogonal decyl chains to generate a micro-segregated layer structure. Octa-acid TAPs with shorter alkyl spacers form edge-on structures in Langmuir monolayers upon compression and are not free of 3-dimensional aggregates based on observations by Brewster angle microscopy (BAM). All octa-acid TAPs are prone to spontaneous self-assembly that is attributed to strong interactions between carboxylic acid groups. Aggregation and spontaneous self-assembly can be minimized by deprotonation of the carboxylic acid groups but all octa-acid TAPs become water soluble when more than four carboxylic acid groups are deprotonated at a pH higher than 8. Cu(II) chelates of the octa-acid TAPs were also prepared but are unsuitable for Langmuir monolayer formation because of insufficient solubility in spreading solvents. Langmuir and LB monolayers of octa-hydroxy TAPs with propyl and undecyl spacers were also studied for comparison. An edge-on orientation of the macrocycle is obtained at higher surface pressures for both TAPs, although a flat-on orientation of the macrocycle in a spider-like confirmation may be present at low surface pressure for the derivative with undecyl spacers. No mesophases are formed by any of the octa-acid and -hydroxy TAPs as confirmed by polarized optical microscopy and thermal analysis measurements. In fact, of the octa-acid TAPs, only the derivative with the longest spacer (decyl) melts at a temperature below the onset of thermal decomposition.

Crosslinked poly(acrylic acid) (XPAA) made by copolymerization of acrylic acid and ethylene glycol dimethacrylate in bulk was further reacted with 80% ethoxylated polyethyleneimine, and the latter insolubilized by treatment with glutaraldehyde. The resulting composite sorbent, XPAA(EPEI.XG), containing carboxylic acid groups and weakly basic tertiary amine groups in close proximity in the same resin bead exhibited thermally regenerable desalination property, simulating the well‐known Sirotherm™ resins. For NaCl and MgCl2, the sorbent has saturation capacities of 0.796 and 0.839 meq/g (dry) sorbent, respectively, at 30°C but less than 0.1 meq/g (dry) sorbent at 80–90°C. The equilibrium sorption data at 30°C fit well to both Langmuir and Freundlich isotherms for single‐component sorption and to Butler‐Ockrent and Jain‐Snoeyink models for bicomponent sorption. Although the sorption of NaCl exhibits a plateau in the pH range of 4–5, that of MgCl2 increases sharply above pH 4 because of additional sorption by cation exchange at the ionic sites formed at higher pH. The sorption rate data show characteristics of particle‐diffusion controlled ion‐exchange process, yielding diffusivity values of 1.0–1.3 × 10−6 cm2/s for NaCl and 3.0–3.5 × 10−7 cm2/s for MgCl2, in the initial period at 30°C, with the diffusivity falling abruptly in both cases at higher conversions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A novel poly(acrylic acid)/montmorillonite superabsorbent composite with a water absorbency of 1100 times its own weight was synthesized by the graft copolymerization of acrylic acid with a cross‐linking agent in the presence of montmorillonite ultrafine powder. The influence of the amount of crosslinker and montmorillonite on water absorbency has been investigated. It was found that a crosslinker concentration of 0.03 wt% and 30 wt% montmorillonite gave the best results. The collaborative absorbent effect of sodium carboxylate and carboxylic acid groups was superior to that of sodium carboxylate or carboxylic acid groups alone, and the composite with a ratio of about 2/3 for sodium carboxylate to carboxyl acid groups possessed the highest water absorbence.© 2001 Society of Chemical Industry

In this study, waterborne polyurethane (WPU) resins consisted of carboxylic acid and side-chained EO (ethylene oxide) functional groups were prepared via a prepolymer ion-hybrid reaction process. After dipping the WPU on fabrics, the dipped fabrics showed promising deodorization properties for both basic and acidic odors and also showed good wash durability because of the presence of those characteristic groups. Basic odors were neutralized via carboxylic acid groups on the WPU, whereas acidic odors were absorbed by the EO groups through hydrogen bonding. Fourier transform infrared spectroscopy (FT-IR) was used to examine the functional groups of carboxylic acid and EO groups, before and after dipping the WPU on the fabrics. The deodorization properties of the dipped fabrics were associated with the content of the functional groups existing on the WPU molecular chain. Scanning electron microscope (SEM) analysis also revealed that the dipped fabrics had a promising wash durability and deodorization properties after 5 times of laundering because WPU particles were still strongly adhered to the fabrics. More side-chain EO groups, more acetic acid molecules were absorbed; while more-COOH groups in polymer chain, more ammonium molecules were absorbed. Table 2 shows that the synthesized WPU’s possess very highly washed durability.

Carbon black photo-resist (CB PR), containing CB, CB dispersant, photo-curable resins, adhesion promoter, photo-initiator, and solvent, was developed for production of high resolution of black matrix (BM) which is an important light-shielding element on the color filter in liquid crystal display (LCD) industry. This work was divided into two parts: (1) the synthesis and function of each ingredient in CB PR and (2) the kinetic behaviors of photo-polymerization and TEMPO-mediated polymerization related to the compounds synthesized in the first part. In the first part, CB was first treated by CB dispersant in order to prepare a high loading of CB dispersion in an organic solvent (propylene glycol monomethyl ether acetate, PGMEA) up to 10 wt%. Three different kinds of dispersants were taken separately to disperse CB, a commercialized dispersant and two newly synthesized dispersants. These three CB dispersants were effectively adsorbed onto CB by the interaction between amino-containing anchoring groups of dispersant and carboxylic acid group on CB surface. They had a moderate chain length to provide a steric repulsion for CB. In addition, the influences of amount and structure of these dispersants on the stability and light-shielding property of CB were discussed. Among these dispersants, one of the newly synthesized dispersants having (meth)acrylate group is an UV-curable CB dispersant, which was synthesized by a two-step process. First, a styrene-(meth)acrylate living copolymer was synthesized as a CB dispersant by TEMPO-mediated living polymerization. In the second step, to render the UV-curable property, additional (meth)acrylate groups were grafted onto the prepared CB dispersant by an urethane linkage reaction. The other newly synthesized CB dispersant was also interesting because it exhibited both UV-curable and alkali-soluble properties, which was capable of forming micro-patterns through an UV-lithographic process. This dispersant was also synthesized by a two-step process. First, UV-curable and alkali-soluble resins were synthesized by the reaction of bisphenol-A epoxy diacrylate with benzophenone tetracarboxylic dianhydride at different molar ratios. Second, to be able to disperse CB particles, these resins were further reacted with an isocyanate-containing methacrylate monomer to produce effective dispersants. Afterwards, CB PRs were prepared by adding photo-initiator and with or without photo-curable resins into the above CB dispersions. However, it was not easy to prepare a BM with both a high opacity and a good resolution upon a low irradiation energy of UV light. This is because CB is a strong light-shielding material which would reduce the photo-sensitivity of CB PR. Besides, the developability of CB PR was strongly retarded by CB since CB can not be soluble in any solvent. In view of this, the selections of photo-initiator and photo-curable resins are critical because they affect the lithographic performance of CB PR. Several photo-initiators were evaluated with respect to their light absorbance and the rate of photo-polymerization in the presence of CB. In addition, several new photo-curable resins were synthesized in this work. UV-curable and alkali-soluble resins were tailored because they can form patterns by an environmental-friendly alkali developer. The influences of photo-sensitivities and concentration of carboxylic acid groups of these resins on the appearance of BM patterns and the energy consumption of UV light were discussed. Finally, a BM with both a high optical density of 4μm-1 and resolution of 10 μm in size upon irradiation of 50-200 mJ/cm2 was successfully produced by using the aforementioned CB PRs through an UV-lithographic process. In addition, the adhesion strength between BM and glass substrate was studied. In the manufacturing process of color filter, the adhesion strength between the BM and glass substrate largely decreased after the ITO sputtering process. To overcome this problem, in this work, a newly synthesized UV-curable silane coupling agent as an adhesion promoter was added into a CB PR. This adhesion promoter was synthesized by the reaction between the hydroxyl group of bisphenol A epoxy diacrylate and the isocyanate group of 3-(isocyanatopropyl)-triethoxysilane. This adhesion promoter containing both acrylate and triethoxysilane groups can be cured upon UV irradiation and form a strong covalent bond with the glass substrate at high temperature, respectively. The influence of this adhesion promoter on the adhesion strength between BM and glass substrate before and after ITO sputtering process was discussed. In the second part, the kinetic behaviors of photo-polymerization of UV-curable resins with carboxylic acid and amino functional groups were investigated. The rate of polymerization and extent of reaction were monitored by using a photo differential scanning calorimeter. A new method combining dark polymerization with pseudo steady state assumption of growing radicals was presented in order to calculate the kinetic constants for propagation, bimolecular termination, monomolecular termination, and the concentration of growing radicals of each resin as a function of extent of reaction. According to the experimental results, it was found that the photo-polymerization was strongly influenced by both functional groups of resins and photo-initiators. The influences of functional groups on the kinetic rate constants and initiator efficiency were discussed in depth. For the CB dispersant synthesized by TEMPO-mediated copolymerization of styrene and (meth)acrylate monomers, the successful living character was observed only at high styrene molar fraction in feed. In view of this, a new kinetic model was established in order to explain the retardant mechanism of the living polymerization of (meth)acrylate. Besides, it was found that TEMPO-mediated polymerization of acrylate could be improved by adding a small amount of polar solvent, DMF (N,N-dimethylformamide) as a rate-enhancement agent. Finally, by using this kinetic model and experimental results, the kinetic rate constants in the TEMPO-mediated polymerization were then calculated and discussed.

Crosslinked poly(acrylic acid), PAA, and poly(2‐acrylamidoglycolic acid), PAAG, were synthesized by radical polymerization. Both resins contain carboxylic acid groups. PAA at basic pH exists basically as an acrylate anion and PAAG shows three atoms or groups, carboxylic acid, hydroxyl, and amide groups, that can act as ion exchanger or chelating groups. Both resins are studied as adsorbents to trace metal ions from saline aqueous solutions and natural sea water and their properties by Batch equilibrium procedure are compared. The metal ions studied under competitive and noncompetitive conditions were Cu(II), Pb(II), Cd(II), and Ni(II). The effects of pH, time of contact, amount of resin, temperature, and salinity were studied. Resin PAA shows a high affinity (&gt;80%) for Cu(II) and Cd(II) and resin PAAG shows also a high affinity for Ni(II), Pb(II), and Cd(II). By treatment of the metal ion‐loaded resin with 4M HNO3 it is possible to recover completely the Cu(II) ions from resin PAA and Ni(II) and Pb(II) from resin PAAG. The metal ion retention properties were studied with natural sea water. For those natural sea waters containing Cu(II) and Cd(II), the resins showed a high affinity for Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 697–705, 2006

Five 1,3-alternatethiacalix[4]arene derivatives bearing carboxylic acid and/or urea hydrogen-bonding groups were prepared and their crystal structures were determined by single-crystal X-ray diffraction methods. In compound 1, where the pendant arms are all adorned with carboxylic acid groups, the pendants all orientate along the base of the molecular axis. An interesting three-dimensional network of "endo-inclusion" aquatubes is formed by stacking the water contained cavities of 1 up and down. While concerning to the other four compounds to which the urea groups are introduced, their pendant arms either orientate towards the inner side of the cavities, or orientate towards the outside, depending on the types of hydrogen-bonding groups and the position of these groups. When the urea groups are in the same side (compounds 2, 4 and 5), the opposite chains in the molecule will locate away from each other which may be due to the steric repulsions. But when the urea group and carboxylic acid group are in the same side (compounds 3 and 4), the opposite chains all orientate inwards because of the intramolecular, inter-chain hydrogen bonds between the opposite chains. Although these four compounds can also self-assemble through the cavity stacking motif, the inwardly orientated pendant arms which protrude into the thiacalixarene cavity obstruct the channels.

Reactive melt processing of different types of diamines with polyethylene containing carboxylic acid groups and polystyrene containing anhydride groups was carried out. The reactivity of primary, secondary, and tertiary diamines with these acid polymers was determined using various techniques. Molecular weight increases due to crosslinking were observed through (1) changes in the torque during the reactive processing, (2) decrease in melt flow indices, and (3) decrease in solubility of the reaction products. The chemical compositions of the reaction products were examined by Fourier transform infrared (FTIR) spectroscopy. Thermal analysis using differential scanning calorimetry (DSC) was carried out to determine the crystallization behavior, glass transition temperatures, and thermal stabilities of the reaction products. Results show that the primary amine is the most reactive towards carboxylic acid or anhydride groups followed by the secondary and then the tertiary amine. Anhydride groups on polymers are of higher activity towards secondary or primary amino groups than carboxylic acid groups in the nucleophilic acyl substitution reactions. Reaction products crosslinked with the primary diamine are less stable than their parent acidic polymers. On the other hand, crosslinking with the secondary or tertiary diamine gives products with higher thermal stability than the parent acidic polymers. The formation of reversible and irreversible crosslinks with different types of diamines is also reported. © 1992 John Wiley &amp; Sons, Inc.

A vacuum adsorption apparatus has been used for vapour-phase chemical derivatisation of standard polymers, to identify specific reactions for carboxylic acid and carbonyl functional groups. The reactivity and selectivity of trifluoroethanol (TFE)–pyridine-di-tert-butylcarbodiimide and 3-(trifluoromethyl)phenylhydrazine for these respective groups were studied. Depths of reaction were also investigated using F 1s/F 2s peak intensity ratios determined by X-ray photoelectron spectroscopy (XPS). The TFE–/pyridine-/di-tert-butylcarbodiimide system was found to be suitable for the selective derivatisation of carboxylic acid groups, achieving ca. 75% conversion of carboxylic acid groups. The depths of fluorine incorporation for both the TFE and TFAA reactions were found to be invariant with reaction time over the XPS sampling depth for the range of conditions studied. Derivatisation of carbonyl groups using 3-(trifluoromethyl)phenylhydrazine was not sufficiently selective, reactions being observed with hydroxy and carboxylic acid groups. Flame treatment of polyethylene produced oxidised surfaces with a variety of functional groups. Using the methods described above and previously reported the hydroxy and carboxylic acid group concentrations were found to be invariant with flame intensity, with the latter having the consistently lower concentration.