Surface modification of poly-D,L-lactic acid film with plasma graft polymerization

Lihua LI; Shan DING; Ye RAN; Jinhuan TIAN; Changren ZHOU

ABSTRACT

BACKGROUND:

Polylactic acid(PLA)surface is hydrophobic and there are no nataral recognition sites,so its application is limited.Many different strategies have been studied such as composition and chemical Drafting,to produce hydrophilic groups.However,these traditional methods are always involved in complex process and many organic reagents,resulting in decrease of biocompatibility.

OBJECTIVE:

To conduct the surfacr modification of PL.A and improve its hydrophilicity with low temperature plasma treatment.

DESIGN:

Controlled observation.

SETTING:

Department of Materials Science and Engineering in Jinan University.MATERIAISThe experiment was processed from October 2004 to October 2005 at Guangzhou Research Center of Artificial Organs and Materials Engineering(Ministry of Education).The mainly used materials werePoly-D,L-lactic acid(Mr 2.9×104,Shandong Medical Instrument Institute),N-vinyl-pyrrolidone(NVP,Acros Company,purified before use).

METHODS:

The materials were treated in the plasma reactor under different conditions(power=150 W,t=3,2,1 minutes;power=30 W,t=10,8,5,3,1 minutes)to choose the optimal condition,and then PLA were grafted with NVP by gas phase polymerization and liquid polymerization,respectively.MAIN OUTCOME

MEASURES:

THe surface morphology of the films was observed with scanning electron microscopy and atomic force microscopy.The hydrophilicity of native and treated material surfaces was measured using a water contact angle meter.Surface composition was detected with Fourier transform infrared spectrometer.Mass changesmeasurement was applied to characterize the grafting efficiency.

RESULTS:

Scanning electron microscopy and atomic force microscopy showed that the plasma medified materials possessed coarse surface with pores and notches.Water contact angles decreased obviously from 78°to 50°after grafting,Fourier transform infrared spectrometer showed a new absorption peak at 1 637.19 cm-1,which corresponded to the carbonyl stretch vibration absorption of amide group in poly-N-vinyl-pyrrolidone.After the plasma treatmerlt at low temperature.the mass change ratio of PLA film material was-0.6.

CONCLUSION:

The plasma treatment and polymerization can improve the hydrophilicity and cause coarsr surface of PLA material,which will be helpful for the cell attachment.