Effect of ion-plasma treatment on the surface physic-chemical properties of materials based on polylactide and hydroxyapatite

In the present work the effect of silver and carbon ions implantation at irradiation dose of 110¹⁶ ions/cm², accelerating voltage 20 kV and of treatment by low-temperature argon plasma at varying temperature and pulse durations of 1 and 5 /us on physical and chemical properties of a polylactic acid/hydroxyapatite composite surface is presented. The elemental composition of the composite surface before and after modification was investigated by X-ray photoelectron spectroscopy. It was found that under ion-plasma exposure, reverse processes are observed that occur under processing conditions according to the results of X-ray photoelectron spectroscopy. It is shown that the surface modification affects the change in the chemical composition: a change in the atomic content of carbon and oxygen is observed. After ion implantation, carbonization of the surface was occurred, since there are more carbon bonds. With plasma modification, oxidation was occurred due to an increase of oxygen atoms on the surface. It was revealed that under surface treatment, parallel reactions are observed: destruction and cross-linking of polymer bonds. During ion-plasma treatment, the calcium-phosphate ratio increases; therefore, energy modification affects the stoichiometry of hydroxyapatite in the composition of the composite material. The contact angle was measured by the lying drop method in contact with water, glycerol, and ethylene glycol. It was found that the surface modification affects the hydrophobic / hydrophilic balance of the composite material’s based on polylactic acid and hydroxyapatite surface. It has been proved the bombardment of silver and carbon ions into the composite surface the hydrophobicity was increased. Plasma treatment affects on improving the wettability of the material surface. A decrease in the value of the contact angle is observed. This process is accompanied by an increase in free surface energy, which indicates an improvement in the adhesion characteristics of the plasma-modified material.

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