ESCA grafted surfaces

Table V. Influence of Siloxane Graft Molecular Weight and Composition on Surface Composition of PMMA-g-PSX Copolymers by Variable Angle XPS (ESCA) (Copolymers 5 wt.% PSX)...

ESCA analysis showed a similar trend of incomplete surface coverage for the IK systems. Also, no domains were visible in any of the IK styrenic graft systems by TEM. There is an expected trend with respect to solubility parameter, p(t-butyl styrene) (6 s 8.1) has a solubility parameter much closer to that of polydimethylsiloxane (S a 7.3) than does p(p-methyl styrene) which is closer than p(styrene) (S s 9.1). 

It is therefore unnecessary to alter the chemical properties of the bulk material, e.g. by using vapor phase deposition of sensitizer and monomer. This can be seen by comparison of ATR-IR and ESCA spectra of grafted PP surfaces (Figure 3). 

Figure 3. Reflection infrared spectra (ATR-IR) of a polypropylene-j surface before (A) and after (B) grafting with acrylamide (AM) by the vapor phase process (above). ESCA spectra of the same surface before (dotted lines) and after (full lines) the surface grafting (below).

The surface grafting of a commercial sheet of poly(ethylene tere-phtalate) was analyzed by ESCA spectra and dye adsorption. The sheets were washed with acetone to remove impurities and then grafted by irradiation for 2 and 20 min. (Figure 9). The blank sample showed no Nls peak in the ESCA spectrum. After grafting the Nls peak increased with increasing grafting time. 

Figure 9. Wide scan ESCA spectra of polyester film surface (PET) before grafting (A) and after grafting for 2 and 20 min. (B and C) with acrylamide (AM) using the vapor phase method.

For the two methods, the resulting grafting of functional monomers, e.g. acrylic acid and acrylamide, has been measured by multiple reflection IR spectra, ESCA spectra, and dye adsorption from an aqueous solution of crystal violet. The measurements indicate that the inert surfaces of the polymer substrates are modified by a complete surface layer of the grafted monomers. 

Polyethylene split film ESCA spectra, 183/ kinetics of surface grafting with acrylonitrile, 184/... 

Figure 5. ESCA measurements (A) untreated OPP film (B) OPP film after surface grafting with AM (17)...

The methods widely used in characterizing the surface grafting onto films are UV, attenuated total reflection (ATR) IR, X-ray-photoelectric spectroscopy (ESCA), contact angle measurement and other techniques applicable to the characterization of the surface treatments of polymeric substances. 

Lin, H.-B., et al., Surface properties of RGD-peptide grafted polyurethane block copolymers Variable take-off angle and cold-stage ESCA studies. Journal of Biomaterial Science Polymer Edition, 1993, 4(3), 183-198. 

The surface reactions of all the modified PUs were confirmed by ATR-FTIR and ESCA. The characteristic peaks of -NCO, -OH, and -SO2 on modified PUs were identified at 2250 cm l for PU-HMDI, 3300-3600 cni" for PU-PEO, and near 1030 cm"l for PU-PEO-SO3, respectively. As shown in Table 1, ESCA data allow us to support well IR results, as more 0 atomic t for PEO grafted PUs and higlier S atomic t for all the sulfonated PUs were determined. 

Spectroscopic methods have been reviewed elsewhere but recent applications of ESCA for study of polymers are interesting. Much of the work in this area has been carried out by Clark, who has reviewed his and other work. " The ESCA method has proved particularly useful for studies of RF plasma modification of polymer surfaces. - Briggs et al. have used X-ray photoelectron spectroscopy to study surface oxidation of polyethylene and its effect on adhesion and Hiraoka and Lee used ESCA to study surface changes in polymers under electron impact and u.v. irradiation. Finally, Ratner et al. used ESCA to follow the grafting of water-compatible polymers into polymer substrates. 

Surface Analysis of Grafted fPTFE Plates by means of ESCA. The... 

Blends of PVC with the plasma-modified LDPE surfaces (by either carbon tetrachloride or VCM) led to somewhat different mechanical test results. It is known that VCM, if plasma polymerized alone, yields a PVC-like molecules [40]. Although there is no study available either for the effects of VCM or carbon tetrachloride plasma treatment of PE, the former is hoped to produce PVC-like grafts on PE, while the latter a chlorinated hydrocarbon-like grafts and products (after a small scale decomposition reactions of stable species produced in plasma). Extensive characterization of plasma treated surfaces by ESCA is being conducted, but results are not yet complete. 

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