| Poly(acrylic ester)hydrogels were widely used in intraocular lens and contact lens due to their excellent optical properties and biocompatibility.In the present work,a kind of poly(acrylic ester)hydrogel replacement biomaterial was prepared which wanted to be used in intraocular lens.The bulk copolymerization behavior of hydrophilic hydroxyethyl methacrylate with hydrophobic methyl metharylate or butyl metharylate was studied during three steps with different polymerization temperature.This polymerizing process could be used to prepare poly(acrylic ester)hydrogel with good optical and good elastic performance,foldable and moderate water absorbing capacity.Poly(acrylic ester)homopolymer and copolymer were prepared by the above process,and the optical performance,calcium deposits,glass transition temperature,equilibrium water content of polymers and its hydrogels obtained by different ratios of monomers were systematically investigated.The main investigation and results were as follows:(1)With hydroxyethyl methacrylat and methyl metharylate or butyl metharylate as monomers,azodiisobutyronitrile as initiator(0.1wt%to total monomer)and ter-ethylene glycol dimethacrylate as cross linker,polymers were prepared through bulk polymerization of three periods of temperatures (60℃25min;50℃60h;80℃10h),then hydrogels were obtained through soaked them in deionized water for a period of time.Monomer conversion was nearly one handrend percentage.(2)In the visible wavelength range from 400nm to 700nm,the light transmittance performance of copolymers and their hydrogels contained hydroxyethyl methacrylat and methyl metharylate with different ratios(100:0, 90:10,70:30,50:50,30:70,0:100)was researched,and the effects of ratios of monomers and cross linker on the material's surface hardness and equilibrium water content was investigated.The results showed that the average light transmittance and the equilibrium water content of the obtained hydrogels increased with increasing the amount of hydrophilic monomer from 0 to 100%, and hydrogel's was higher than its polymer's,however,the hardness decreased,and hydrogel's was reduced significantly compared with its polymer's.Moreover,the average light transmittance and the equilibrium water content of copolymers reduced with increasing amount of multigunctional monomer.(3)The refractive indexes of polymers and their hydrogels were derived approximately from the Fresnel relationship and the values of measured light transmittance for the first time;at the meantime,those were calculated by means of the effect of radicals on gram-molecule refraction index,then by combining the two,the ranges of their refraction index respectively were:the refraction index of Poly(HEMA-co-MMA)was about 1.49, Poly(HEMA-co-i-BMA)was from 1.49 to 1.48,and Poly(HEMA-co-n-BMA) was from 1.48 to 1.47.(4)It was also first time that through the variation of average light transmittance,calcium deposits of different kinds of hydrogels was researched by soaked in sodium phosphate buffer solution contained calcium which simulated human eye's aqueous humor.Results showed that light transmittance of hydrogels changed very small after soaked in this buffer solution for 46d,and it still maintained a high level.(5)Considered the hydrogels' all performances,the optimum technical condition for preparation were obtained,that is,when the mass ratio of hydrophilic monomer and hydrophobic monomer was 90:10,the light transmittance of this copolymer hydrogel was 92.8%,higher than the national standard for soft contact lens transparency requirements(92%),the surface Shore A hardness was 30,the equilibrium water content reached 57.1%,a relatively high level light transmittance could be maintained in the environment contained calcium.The above hydrogel will become a suitable biomedical materials being applied to human eyes. |
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