Corona chemical composition

The modification of the chemical composition of polymer surfaces, and thus their wettability with chemical substances, can be realized in different ways electric discharges more commonly called Corona effect, oxidation by a flame, plasma treatment, UV irradiation and also UV irradiation under ozone atmosphere. Numerous studies have been devoted to the effects of these different treatments. More recently, Strobel et al. [204] compared the effects of these treatments on polypropylene and polyethylene terephthalate using analytical methods such as E.S.C.A., F.T.I.R., and contact angle measurements. They demonstrated that a flame oxidizes polymers only superficially (2-3 nm) whereas treatment realized by plasma effect or Corona effect permits one to work deeply in the polymer (10 nm). The combination of UV irradiation with ozone flux modifies the chemical composition of the polymers to a depth much greater than 10 nm, introducing oxygenated functions into the core of the polymer. 

Figure 3.5 General chemical composition of triblock copolymers with hydrophilic PPO and hydrophobic PEO parts (top), giving rise to micelles with a corona of PEO blocks (middle), leading to composites/mesoporous materials in which the mesopores are connected via micropores (bottom).

The last two theories described (chemical and thermodynamic) are intimately linked together because both of them induce a modification of the chemical composition at the surface. On the one hand, this modification can change the thermodynamic parameters (wettability) of the surface. On the other, changes in chemical composition influence the chemical adhesion established between the adherend and the adhesive layer. Numerous treatments are available for surface modification with coronas [8], plasmas [9, 10], lasers [11, 12], ion-assisted reactions [13], or coupling agents [14, 15]. All these treatments do not only change the chemical composition they can also affect the roughness, the orientation of macromolecular chains, and the mechanical behavior. 

While not changing the chemical composition of the fiber extensively, physical treatments cause variations in structural and surface properties of the fiber and consequently affect the mechanical bonding to the polymer matrix. Thermal treatment, corona and plasma treatments can be given as examples to physical treatments applied on plant fibers [3]. Ragoubi et al. [33] reported an increase in mechanical and thermal properties of reed fiber-reinforced PLA and PP composites upon corona discharge treatment of fibers. 

Fig. 1 Schematic representation of co-assembly of two oppositely charged ionic-neutral diblock copolymers in water into complex coacervate core micelles, in short C3Ms, with a core comprising the oppositely charged monomers surrounded by a shell of neutral, water-soluble monomers. The two monomer types in the corona may mix left) or segregate radially (mid-left), laterally (mid-right) or both radially and laterally (right) depending on the chemical composition of the block copolymers and hence the miscibility and differential solvent quality of the neutral monomers. This may lead to the formation of onion-like micelles, also known as core-shell-corona structures (mid-left), Janus micelles (mid-right) or patchy micelles, also known as raspberry-like micelles (right). Figure from Ref. [188]...

Depending on their chemical composition, they wUl require mechanical, chemical, and physical pretreatment or priming to enhance coating adhesion. Since mechanical pretreatment consists of abrasion, its effect on the substrate must be considered. Chemical pretreatments involve corrosive materials which etch the substrates and can be hazardous. Therefore, handhng and disposal must be considered. Physical pretreatments consist of plasma, corona discharge, and flame impingement. Process control must be considered. 

Data about corona-treated PP [149] are compared with those reported by Morra et al. for oxygen plasma-treated PP (see also Section V.D) [125, 126]. For both oxidation processes the chemical composition of a 2-5 nm layer into the treated polymer surface, analyzed by XPS, is very stable at ambient temperature. 

LC-APCI-MS is a derivative of discharge-assisted thermospray, where the eluent is ionised at atmospheric pressure. In an atmospheric pressure chemical ionisation (APCI) interface, the column effluent is nebulised, e.g. by pneumatic or thermospray nebulisation, into a heated tube, which vaporises nearly all of the solvent. The solvent vapour acts as a reagent gas and enters the APCI source, where ions are generated with the help of electrons from a corona discharge source. The analytes are ionised by common gas-phase ion-molecule reactions, such as proton transfer. This is the second-most common LC-MS interface in use today (despite its recent introduction) and most manufacturers offer a combined ESI/APCI source. LC-APCI-MS interfaces are easy to operate, robust and do not require extensive optimisation of experimental parameters. They can be used with a wide variety of solvent compositions, including pure aqueous solvents, and with liquid flow-rates up to 2mLmin-1. 

Almost all of the work diich has been done to date has involved a substrate of loosely defined stoichiometry, that is to say, an experimentally treated polymer surface of unknown composition. In several cases indicated, chemical reaction produced addition of an oiq gen species, which was not expected. For instance, no oxygen-containing reagent was used in the sodium-treated PTFE or in some of N2 or Ar corona-treated low-density polyethylene, yet copious amounts of oxygenated species were formed. What is needed for a method that can be said to quantitatively label the surface of a polymer is outlined below. Method Requirements for quantitative derivatization of polymers ... 

It has been pointed out that surface treatment of fibers significantly improves the physical strength of the composite (14). The reinforcing fibers should be surface-treated before use. Examples of the treatment include chemical treatment, such as silane compounds and titanates (20), and (fiysical treatment such as corona and ultraviolet pl na (14). 

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