• Journal of the Korean Chemical Society
• /
• v.60 no.3
• /
• pp.181-186
• /
• 2016

The hydrophilic ophthalmic lens with addition of 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA) and Ag nanoparticles were manufactured. And also, the cross-linker ethylene glycol dimethacrylate (EGDMA) and the initiator azobisisobutyronitrile (AIBN) were used for polymerization. The polymerization of the hydrogel lens material was conducted through thermal polymerization in 100 ℃ for 1h. The optical and physical characteristics of hydrogel lens were evaluated by measuring water content, refractive index and optical transmittance. The water content of sample containing HEA, HEMA and HPMA was in the average of 82.12%, 37.06% and 21.57%, respectively. And also, refractive index of the sample containing HEA, HEMA and HPMA was in the average of 1.3540, 1.4330 and 1.4649, respectively. In case of the optical properties of the sample, the results showed that the near-UV transmittance was 82.67%, 80.32% and 79.83%, and the visible transmittance was 89.72%, 88.24% and 86.89%, respectively. And also, optical transmittance of the sample containing Ag nanoparticles showed that the near-UV transmittance of 10.59% and visible transmittance of 43.74% were obtained. From the results, the molecular length influenced on the water content and refractive index of the polymerized material.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.1
• /
• pp.43-49
• /
• 2014

Purpose: The physical and optical characteristics of hydrophilic contact lens polymerized with addition of glycerin and PVP(polyvinylpyrrolidone) in the basic hydrogel contact lens material were evaluated. Methods: This study used glycerin and PVP(polyvinylpyrrolidone) with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Results: Measurements of the physical characteristics of the copolymerized material including PVP(polyvinylpyrrolidone) showed the refractive index of 1.4382~1.4288, tensile strength of 0.3446~2542 kgf and water content and contact angle of sample showed the increase of 13.49% and decrease of 21.44% independently. And also, the physical characteristics of the copolymerized material including glycerin showed the refractive index of 1.4330~1.4328, tensile strength of 0.2974~0.2854 kgf, water content 35.58~36.53% and contact angle of sample showed the decrease of 37.64%. Conclusions: Based on the results of this study, the produced copolymers is suitable for conventional lens with high wettability. Also, glycerin minimized the changes of water content and refractive index at the same time, increased the wettability of the hydrogel lens materials.

• Journal of the Korean Chemical Society
• /
• v.55 no.2
• /
• pp.283-289
• /
• 2011

This study used glycerol dimethacrylate with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), MA (methacrylic acid) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Measurement of the physical properties of the copolymerized polymer showed that the water content was 22~32%, refractive index was 1.442~1.463 and visible ray transmittance 90.0~90.5% while the contact angle showed a distribution between 56 and $65^{\circ}$. Also, the measurement showed that the decreased amount of contact angle of the copolymer measured using the sessile drop method ranged between $9.89^{\circ}$ and $18.99^{\circ}$ with increase of glycerol dimethacrylate. Based on the results of this study, the produced copolymer is suitable for use as a material to high wettability ophthalmic lenses.

• Journal of the Korean Chemical Society
• /
• v.54 no.6
• /
• pp.761-765
• /
• 2010

Poly (N,N-dimethylacrylamide) is very useful in various fields due to its remarkable properties, such as water solubility and biocompatibility. This study used N,N-dimethylacrylamide with the cross-linker EGDMA (ethylene glycol dimethacrylate), HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (N-vinyl-2-pyrrolidone) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Measurement of the physical properties of the copolymerized polymer showed that the water content was 36 - 42%, refractive index was 1.433 - 1.426 and visible ray transmittance 90 - 91% while the oxygen permeability showed a distribution between 13.1 and $21.29{\times}10^{-11}(cm^2/sec)$ ($mlO_2/mL{\times}mmHg$). The measurement showed that the increased amount of oxygen permeability of the copolymer measured using the polarographic method range between 11.0% and 80.5%. Based on the results of this study, the produced copolymer is suitable for use as a material to high oxygen permeability hydrogel lenses.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.4
• /
• pp.437-443
• /
• 2015

Purpose: This study evaluated the optical and physical and characteristics of soft contact lens polymerized with addition of 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine-4-carboxylic acid in the basic hydrogel contact lens material. In particular, the utility of 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine- 4-carboxylic acid as a hydrogel contact lens material was investigated. Methods: In this study, 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine-4-carboxylic acid were used as additives. Also, 2-hydroxyethyl methacrylate, acrylic acid, methyl methacrylate and a cross-linker EGDMA were co-polymerized in the presence of AIBN as an initiator. Results: The physical properties of the produced polymers were measured as followings. The water content of 34.54~37.15%, refractive index of 1.4320~1.4342, tensile strength of 0.2872~0.3608 kgf and contact angle of $57.82{\sim}79.57^{\circ}$, UV-B transmittance of 76.8~82.4% and UV-A transmittance of 84.6~86.6% were obtained respectively. Conclusions: Based on the results of this study, contact lens material containing 3-chloropyridine-4-carboxylic acid and 3-fluoropyridine-4-carboxylic acid is expected to be able to used as a material for high wettability and UV-block hydrogel contact lens.

• Polymer(Korea)
• /
• v.36 no.3
• /
• pp.338-343
• /
• 2012

Interfacial properties of commercially available soft contact lens hydrogels were studied to understand thermodynamic phenomena of protein adsorption. Hydrogel particles ($1{\times}1mm^2$) with varying water wettability were exposed to bovine serum albumin solutions for an hour. The remained albumin solutions were analyzed with Bradford assay method. The amount of protein adsorbed to hydrogels increased with protein solution concentrations following Langmuir isotherm. The partition coefficient ($P$) and Gibbs free energy cost of dehydrating the surface region by protein displacement upon adsorption increased with increasing hydrophilicity of contact lens. Understanding of physical chemistry in protein adsorption to contact lens materials enabled elucidating relationships between surface energy and albumin adsorption capacity.

• Journal of the Korean Chemical Society
• /
• v.54 no.3
• /
• pp.310-316
• /
• 2010

Nanoparticle with antimicrobial property has been applied to various fields. This study added silver/platinum nanoparticles to HEMA (2-hydroxyethylmethacrylate), NVP (N-vinyl pyrrolidone) and MMA (methylmethacrylate) in various concentrations and copolymerized by heating at $70^{\circ}C$ for 40 minutes, $80^{\circ}C$ for 40 minutes, and finally, $100^{\circ}C$ for 40 minutes. The particle size of used nano silver and platinum was 10 ~ 20 nm respectively. Using the polymer produced through the copolymerization process, the authors have produced a contact lens and measured the physical characteristics which showed water content of 34.29 ~ 39.00%, refractive index of 1.422 ~ 1.430, visible transmittance of 78.8 ~ 92.5% and tensile strength of 0.149 ~ 0.179 kgf. The ophthalmic lens material produced using silver/platinum nanoparticles satisfied the basic physical properties required for contact lens application.

• Polymer(Korea)
• /
• v.32 no.6
• /
• pp.501-508
• /
• 2008

Small injection molded articles such as lens and mobile product parts are usually molded in multi-cavity mold. The problem occurring in multi-cavity molding is flow unbalance among the cavities. The flow unbalance affects the dimensions and physical properties of molded articles. First of all, the origin of flow unbalance is geometrical unbalance of the delivery system. However, even the geometry of the delivery system is well balanced, cavity unbalance occurs. This comes from the temperature distributions in the cross-section of runner. Temperature distribution depends upon injection speed because heat generation near runner wall is high at high injection speed. Among the operational conditions, injection speed is the most significant process variable affecting the filling unbalances in multi-cavity injection molding. In this study, experimental study of flow unbalance has been conducted for various injection speeds and materials. Also, the filling unbalances were compared with CAE results. The dimensions and weights of multi-cavity molded parts were examined. The results showed that the filling unbalances vary according to the injection speeds and resins. Subsequently, the unbalanced filling and pressure distribution in the multi-cavity affect the dimensions and physical states of molded parts.

• Polymer(Korea)
• /
• v.38 no.2
• /
• pp.193-198
• /
• 2014

Lens and DVD require high quality of optical property. Conventional injection molded products contain high residual stress and this invokes birefringence since high cavity pressure and high temperature variation are involved in a molding process. Thus these products are often molded by injection compression molding in order to minimize the residual stress through reducing cavity pressure and uniform cavity pressure. In this study, molding parameters affecting molding quality such as property uniformity in injection compression molding were investigated through experiment. Molding quality deviations among the cavities in multi-cavity mold were also studied. Transparent resins, PC and PS were used in this study. Compression gap, compression speed, compression force, and compression delay time for processing variables in injection compression molding were applied in experiment. Compression force, compression delay time, and compression gap significantly affected the optical property of product. The degree of influence of process variable on the product quality was different in different resins. This implies that the optimal operational conditions in injection compression molding existed for each resin according to flow property.