Polyethylene Obtained by Plasma Polymerization of Hexene Pilar Morales, 1,2 Lidia M. Go´mez, 1,2 M. Guadalupe Olayo, * 1 Guillermo J. Cruz, 1 Cuauhtemoc Palacios, 1,3 Juan Morales, 4 EduardoOrdon˜ez 1 Summary: This work presents the synthesis by plasma of polyhexene (PHe) as an alternative to produce thin films of polyethylene (PE) without catalysts or other chemical compounds. PHe was obtained using 1-Hexene in glow discharges at 13.5 MHz, 10 1 mBar and power between 40 and 120 W. The results showed that plasma PHe had the typical CC and CH bonds of PE with other bonds, as C¼C and C¼O, that indicate unsaturation and oxidation in the polymers. The thermal degradation of PHe starts at 250 8C, 100 8C lower than in PE. However, at T > 500 8C, PHe has more residual mass than PE. In the interval of 20–100 8C, the electrical conductivity of PHe was calculated between 10 11 and 10 8 S/cm. These results suggest that the structures of PHe and PE are similar and that the plasma polymerization of 1-hexene is an alternative route to obtain oxidized and unsaturated varieties of PE as thin films on different surfaces. Keywords: plasma; polyethylene; polyhexene; polymerization Introduction The applications of PE are based on its simple structure which results in high chemical passivity, low electrical conduc- tivity and a hydrophobic behavior in the polymer. PE is used as an electric insulator and as protective films in coating treat- ments and packaging material. The biome- dical applications of PE are increasing constantly based on its biochemical passiv- ity. [1–3] These characteristics reduce its degradation, but on the other hand com- plicate its possibilities to combine with other materials with different physicochem- ical properties like metals. PE is produced generally from ethylene in gas-phase polymerizations using differ- ent catalysts of Ti, V, Cr or Mg. [4–6] However, in order to obtain PE without catalysts, initiators, solvents or other che- mical reagents that could contaminate the polymers, different syntheses have to be considered. Polymerizations with these conditions can be developed by plasma, where the electrical field applied to the synthesis produces ions and excited mole- cules that make the function of initiators and catalysts. Plasma polymerizations have been used to obtain polymers with a semi-controlled purity, hydrophobicity and electric conduc- tivity. This technique has also been used in the superficial modifications of solids to enhance the electrical properties for micro- electronic or optical devices [7] and in the growing of cells in biomedical applica- tions. [8] In this work, we study the plasma polymerization of 1-hexene to produce thin films of PE in chemical reactions without catalyst or other chemical reagents that could be harmful in biomedical applica- tions. Macromol. Symp. 2009, 283–284, 13–17 DOI: 10.1002/masy.200950903 13 1 Departamento de Fı´sica, Instituto Nacional de Inves- tigaciones Nucleares, Apdo. Postal 18-1027, D.F., CP 11801, Me ´ xico E-mail: guadalupe.olayo@inin.gob.mx 2 Instituto Tecnolo ´ gico de Toluca, Av. Tecnolo ´ gico s/n, La Virgen Metepec, Mex., C.P. 52140, Me ´ xico 3 Universidad Polite ´cnica del Valle de Toluca, Loma Real s/n, La Loma, Zinacantepec, Mex., CP 51355, Me ´ xico 4 Departamento de Fı´sica, Universidad Auto ´ noma Metropolitana, Apdo. Postal 55-534, D.F., CP 09340, Me ´ xico Copyright ß 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim