Journal of Korean Ophthalmic Optics Society (한국안광학회지)

The Korean Ophthalmic Optics Society (한국안광학회)
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Polymerization of HEMA by Electron beam Irradiation and Fabrication of Soft contact lens

전자빔조사에 의한 HEMA의 중합과 소프트콘택트렌즈 제조

  • Hwang, Kwang-Ha (Dept. of Optometry and Optic Science, Dongshin University) ;
  • Shin, Joong-Hyeok (Radiation Instruments Research Division, Korea Atomic Energy Research Institute) ;
  • Sung, Yu-Jin (Dept. of Optometry and Optic Science, Dongshin University) ;
  • Jeong, Keun-Seung (Dept. of Optometry and Optic Science, Dongshin University) ;
  • Jun, Jin (Dept. of Optometry and Optic Science, Dongshin University)
  • 황광하 (동신대학교 안경광학과) ;
  • 신중혁 (한국원자력연구원 방사선기기연구부) ;
  • 성유진 (동신대학교 안경광학과) ;
  • 정근승 (동신대학교 안경광학과) ;
  • 전진 (동신대학교 안경광학과)
  • Received : 2012.04.27
  • Accepted : 2012.06.16
  • Published : 2012.06.30
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Abstract

Purpose: Polymerization of HEMA(2-hydroxyethyl methacrylate) which can be used in the soft contact lens has been performed by using electron beam(EB) irradiation, and examined the best condition for the polymerization. Comparing the physical properties of the contact lenses to the one fabricated by thermal polymerization method, we check the use possibility of the EB irradiation to the fabrication of the soft contact lens. Methods: We investigated the degree of polymerization of the HEMA according to the composition of the monomer, the additive ratio and the dose of electron beam (0~120 kGy). The degree of polymerization was measured depending on the EB dose to research the best synthetic condition under the EB irradiation. The physical properties of the contact lens such as water content(%), oxygen transmissibility(Dk/t) and optical transmittance were analysed by using the FT-IR results with comparing the two different polymerization method (thermal and electron beam polymerization) with same additive ratio. Results: When the dose of electron beam was above 100 kGy, the degree of polymerization of HEMA was above 99% with regardless using cross-linker and initiator. The water content of the lens fabricated by EB method showed 10% higher than the one by the thermal method which was 40%. The lens fabricated by EB method also showed higher oxygen transmissibility(Dk/t) as same with the water content, and showed twice higher value in the lens fabricated by pure HEMA. According to the FT-IR results, hydrophilic property of the lens fabricated by EB method was increased due to increasing the intermolecular hydrogen bonding. It showed above 90% optical transmittance in the visible range of wavelength on the contact lenses fabricated by the both of two different polymerization method. Conclusions: The polymerization of HEMA without cross-linker and initiator was successful above 100 kGy of EB irradiation. Moreover the lens fabricated from the polymer synthesized by pure HEMA with 100 kGy of EB showed the highest water content and oxygen transmissibility. Therefore EB irradiation is another possible method to synthesize the polymer which can be used for the soft contact lens.

목적: 전자빔(electron beam)을 이용한 HEMA(2-hydroxyethyl methacrylate)의 중합과정에 대한 최적의 전자빔조사(irradiation) 조건을 살펴보고, 전자빔과 일반적인 열중합 방법에 의해 제조된 콘택트렌즈의 물리적 특성을 각각 비교함으로써 콘택트렌즈 제조에 전자빔조사 방법의 활용가능성을 알아보고자 한다. 방법: 중합에 사용된 모노머(monomer)나 첨가제의 구성비 그리고 전자빔흡수선량(0~120 kGy)에 따라 HEMA의 중합정도를 관찰하여 전자빔조사(irradiation)에 의한 중합여부와 최적의 중합조건을 제시하였다. 동일한 반응물 구성비에 대해 전자빔과 열중합의 두 가지 다른 중합방법을 이용하여 고분자를 합성하였다. 각각의 고분자로부터 제조된 소프트콘택트렌즈에 대해 함수율, 산소전달률(Dk/t), 광투과율 등의 물리화학적 특성을 FT-IR 결과를 이용하여 비교 분석하였다. 결과: 전자빔조사선량(0~120 kGy)에 따라 살펴본 HEMA의 중합률은 100 kGy 이상에서 99% 이상으로 나타났으며, 사용된 모노머의 구성비나 광개시제와 가교제 등의 첨가에 무관하게 높은 중합률을 보였다. 전자빔 조사에 의해 제조된 렌즈의 함수율은 열중합 방법에 의해 제작된 렌즈에 비해 10% 이상 높게 나타났다. 산소전달률(Dk/t)도 함수율과 마찬가지로 전자빔조사방법에 의해 제조된 렌즈에서 더 높게 나타났으며, 순수한 HEMA의 경우는 약 2배 정도 높은 값을 보였다. FT-IR 분석결과, 전자빔 조사방법에 의해 제조한 렌즈에서 친수성 증가와 관계되는 OH group의 농도가 증가하였고 이에 따른 분자간 수소결합의 농도가 증가함을 확인하였다. 두 가지 다른 중합방법에 의해 제조된 렌즈의 가시광선(380~800 nm) 영역에서 광 투과율은 제조방법과는 상관없이 유사하였으며, 90% 이상의 높은 값을 나타내었다. 결론: HEMA를 기본으로 구성된 다양한 반응혼합물과 개시제나 가교제의 첨가가 없는 순수한 HEMA에 100kGy 이상의 전자빔을 조사할 경우 중합이 성공적으로 이루어졌다. 또한 순수한 HEMA에 100kGy의 전자빔을 조사하여 중합된 고분자로부터 제조된 콘택트렌즈에서 가장 높은 함수율과 산소전달률을 나타내어 전자빔조사조건에 따라 물리적특성이 다른 콘택트렌즈의 제조가 가능함을 확인하였다.

Keywords

References

  1. Kim TH, Sung AY. Study on the Polymerization of Hydrogel Polymer Containing HEMA and Measurement Method of Oxygen Transmissibility. J Kor Chem Soc. 2009;53(6):749-754. https://doi.org/10.5012/jkcs.2009.53.6.749
  2. Kim TH, Ye KH, Sung AY. Synthesis of Contact Lens Material with High Oxygen Transmissibility Using Polyphosphazene. Korean J Vis Sci. 2009;11(3):203-209.
  3. Cho CS, Kim BC, Kang SW, Sung YK. Homogeneous Graft Copolymerization of (2-hydroxyethyl methacrylate) onto Gelatin. Polymer(Korea). 1987;11(5):417-424.
  4. Joo DJ. Contact Lens Materials. Polymer(Korea). 1985;9(4): 253-260.
  5. Lee JH, Park KR, Nho YC, Son TI. Preparation and Characterization of Hydrogels by Radiation. J Chitin Chitosan. 2003;8(1):10-17.
  6. Chmielewski AG, Chmielewska DK, Michalik J, Sampa MH. Prospects and challenges in application of gamma, electron and ion beams in processing of nanomaterials. Nucl Instr and Meth in Phys Res. 2007;265(1):339-346. https://doi.org/10.1016/j.nimb.2007.08.069
  7. Rashi N, Anil K, Acharya NK, Vijay YK. XPS and AFM surface study of PMMA irradiated by electron beam. Surf Coat Technol. 2009;203(17-18):2600-2604. https://doi.org/10.1016/j.surfcoat.2009.02.054
  8. Burkert S, Schmidt T, Gohs U, Dorschner H, Arndt KF. Cross-linking of poly(N-vinyl pyrrolidone) films by electron beam irradiation. Radiat Phys Chem. 2007;76(8-9):1324-1328. https://doi.org/10.1016/j.radphyschem.2007.02.024
  9. Nouha SA, Mohamed A, EL Hussieny HM, Sakr EM. Thermal and optical properties of electron beam irradiated cellulose triacetate. Mater Chem and Phys. 2008;110(2-3):376-379. https://doi.org/10.1016/j.matchemphys.2008.02.024
  10. Nathawat R, Kumar A, Kulshrestha V, Singh M, Ganesan V, Phase DM, Vijay YK. Surface modification study of low energy electron beam irradiated polycarbonate film. Appl Surf Sci. 2007;253(14):5985-5991. https://doi.org/10.1016/j.apsusc.2006.12.122
  11. Ren L, Yin S, Zhao L, Wang Y, Chen H, Qu J. Study on the surface of fluorosilicone acrylate RGP contact lens treated by low-temperature nitrogen plasma. Appl Surf Sci. 2008;255(2):473-476. https://doi.org/10.1016/j.apsusc.2008.06.060
  12. Rosiak JM, Ulanski P, Pajewski LA, Yoshii F. Radiation Formation of Hydrogels for Biomedical Purposes. Some Remarks and Comments. Radiat Phys Chem. 1995;46(2):161. https://doi.org/10.1016/0969-806X(95)00007-K
  13. ISO. Ophthalmic Optics-Contact Lenses 18369-4:2006, 2006. http://www.iso.org/iso/home.html(10 May 2009).
  14. Chang R. Essential Chemistry, International Ed. Mcgraw-Hill, 1996;266.
  15. Woods RJ, Pikaev AK. Applied Radiation Chemistry: Radiation Processing, 2nd Ed. NY: Wiley-Interscience, 1994;20-58.
  16. Luensmann D, Jones L. Albumin adsorption to contact lens materials: A review. Contact Lens & Anterior Eye. 2008;31(4):179-187. https://doi.org/10.1016/j.clae.2008.05.004
  17. Silverstein RM, Bassler GC, Morrill TC. Spectrometric Identification of Organic Compounds, 5th Ed. NY: John Wiley & Sons, 1991;105-111.