XPS analysis of NH₃ plasma‐treated polystyrene films utilizing gas phase chemical modification

Abstract

SynopsisGas phase chemical modification (GCM) is found to be more preferable as a pretreatment for the XPS surface analysis of polymer materials than the conventional liquid phase treatment because it can circumvent problems such as solvent contamination and swelling. We have tried the quantification of the surface compcsition successfully by estimating the yield of the reaction from model samples. GCM was then applied to correlate the surface composition of NH, plasma-treated polystyrene films with their cell-affinity. The amount of primary-amine and that of carboxylic acid were directly determined by GCM. Although the amount of primary-amine, 15-20% of total nitrogen, did not depend on the treatment intensity, the total amine content for the treated samples increased with the plasma treatment intensity. The quantity of carboxylic acid generated was found to be very small. All treated samples had better cell-affinity than the control. The sample N2 (of medium treatment) showed the best cell-affinity. The most strongly treated sample N3, with larger amine content than N2, showed worse cell-affinity because of the interference by the sputtered SiO, on the surface.Most of the chemical modification reactions have been conducted in liquid phase'-8 except for a few c~s~s ,~~' ' although problems as residual solvent on surface and swelling of the substrate are experienced in the XPS measurement. Gas phase reactions have been tried here to avoid such problems. I n the h t part of the paper, we report a preliminary study of gas phase chemical modification reactions, in which the detection limit and quantitativity are examined for primary amine, carboxylic, and hydroxyl groups on polymer surface.

X‐ray photoelectron analysis of surface functional groups on diamond‐like carbon films by gas‐phase chemical derivatization method

“…The last pair was designated as TFE/DIC. It should be noted that DIC is a more suitable reagent for the gas-phase reaction than DCC (N,N -dicyclohexylcarbodiimide), which has been used for the reaction, [30,32,38] because DIC is liquid at room temperature, whereas DCC is a solid.…”

“…[33,34] Thus the reactions have been performed in the gas phase, which is designated as the gas-phase chemical derivatization (GCD) method. [31,35 -38] Its systematic analysis was established by Nakayama, Takahagi, and co-workers, [38] and has been applied to the surface analyses of carbon fibers [39,40] DLC films, [41] and other carbonaceous materials. [42,43] However, the GCD method has a serious drawback that a derivatization reaction does not always concern the target surface functional group but is also sensitive to other groups.…”

Wettability and Other Surface Properties of Modified Polymers

“…The wettability of surface as well as its biocompatibility can significantly be altered by plasmas containing nitrogen [64]. Cell affinity was enhanced using ammonia plasma treatment on PS [65]. Nitrogen-or ammonia-based plasmas were applied to create amino-binding sites [66] or to increase the peel strength between polymers [67].…”

Analysis of the Functional Groups Formed on the Corona-Treated Cellulose Fibre Sheet Surface by Means of Chemical Modification in Gas Phase-ESCA Technique.

“…By this process, relative intensity Fls/Ois will become less than that of (1) because of the washing out of the low molecular compounds from the surface layer. The de rivatization in gas phase were undertaken by the simi lar method to Nakayama's methods (8)(9)(10). The adopted method was shown in Fig.…”