• 대한화장품학회지
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• 제24권3호
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• pp.111-115
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• 1998

We investigated the stability of all-trans-retinol on the liquid crystalline O/W emulsion composed of mainly alkyl polyglycerine, alkyl polyglucose and glycerine, and compared the activity of all-trans-retinol in the various forms of liquid crystal. Under certain conditions, novel liquid crystalline gel was formed around oil droplets, and layers of this liquid crystalline gel were very wide and rigid. (SWLC; Super Wide Liquid Crystal) SWLC was very helpful to stabilize retinol in O/W emulsion. After storage at 45 C for 4 weeks, all-trans-retinol in O/W emulsion composed of SWLC retained above 85% of the activity upon HPLC analysis, whereas those within no liquid crystalline emulsion gave 47% and normal liquid crystalline emulsion composed of fatty alcohols gave 40 60%. Retinol in oil phase is nealy insoluble in pure water, but in cosmetic emulsion systems can be slightly solubilized into water because emulsifiers and polyols in emulsion systems function as solubilizers. In this case, water in outer phase acts as a media for oxygen transporation$.$and thus destabilizes retinol. As a result, retinol in O/W emulsion has a tendency to become unstable. SWLC surrounding oil droplet which contains retinol is wide and rigid, therefore reduces contact between inner phase and outer phase To make SWLC, properties of emulsifiers are very important phase transition temperature should be high, and the structure of surfactants should be bulky, and their ratio should be suitable to make rigid and wide liquid crystalline gel layer in order to reduce contact between retinol in inner phase and water in outer phase.

• Archives of Pharmacal Research
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• 제26권10호
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• pp.880-885
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• 2003

Research in this paper focuses on the kinetic evaluation of swelling of the liquid crystalline phases of glyceryl monooleate (GMO). Swelling of the lamellar and cubic liquid crystalline phases of GMO was studied using two in vitro methods, a total immersion method and a Franz cell method. The swelling of the lamellar phase and GMO having 0 %w/w initial water content was temperature dependent. The swelling ratio was greater at $20^{\circ}^C than 37^{\circ}^C$ . The water uptake increased dramatically with decreasing initial water content of the liquid crystalline phases. The swelling rates obtained using the Franz cell method with a moist nylon membrane to mimic buccal drug delivery situation were slower than the total immersion method. The swelling was studied by employing first-order and second-order swelling kinetics. The swelling of the liquid crystalline phases of GMO could be described by second-order swelling kinetics. The initial stage of the swelling (t < 4 h) followed the square root of time relationship, indicating that this model is also suitable for describing the water uptake by the liquid crystalline matrices. These results obtained from the current study demonstrate that the swelling strongly depends on temperature, the initial water content of the liquid crystalline phases and the methodology employed for measuring the swelling of GMO.

• Bulletin of the Korean Chemical Society
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• 제21권4호
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• pp.441-445
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• 2000

A new series of three ring type liquid crystalline compounds containing partially fluorinated alkenyl or alkyl side chains together with fluorine substituted cyclohexylbiphenyls were designed and synthesized in this study. The structures of synthe sized compounds were established by 1 H, 13 C and 19 F NMR spectroscopy. The phase transition temperatures of fluorinated liquid crystalline compounds were determined by cross-polarizing mi-croscopy equipped withhot stage. All compounds were found to have nematic liquid crystalline phase with rel-atively low phase transition temperature and wide liquid crystalline temperature range. The dependence of phase transition temperatures on the chainlength falls into three categories; (a) decreasing transition tempera-tures for 4-fluoro-4'-[4-fluoro-4-(1-fluoroalkyl)cyclohexyl]biphenyl (15) series, (b) higher transition tempera-tures for odd numbered chains for 4-fluoro-4'-[4-fluoro-4-(1-fluoroalk-1-enyl)cyclohexyl]biphenyl (14) series, (c) higher transition temperatures for even numbered chains for 4-[4-(1,2-difluoroalk-1-enyl)-4-fluorocyclo-hexyl]-4'-fluorobiphenyl (16) series.

• Journal of Pharmaceutical Investigation
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• 제37권4호
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• pp.243-247
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• 2007

Retinoids have many important and diverse functions and particularly, have been widely used as anti-aging agent and for the treatment of acne and psoriasis in cosmetics. However, retinoids have low stability against the air, light, water, oxygen and heat, thus, to stabilize the retinoids in formulations is very critical procedure. In this study, cubic liquid crystalline phase of monoolein was applied to stabilize the retinylpalmitate (RP) and to enhance the transdermal permeation. Cubic liquid crystalline phase significantly enhanced the stability of RP. After 15 days, the content of RP in the cubic formulation was 94.7% while the content of RP in ethanol solution was below 0.5% at room temperature. Although BHT containing crystalline phase showed the slightly increased stability of RP, there were no significant differences in RP stability between with or without antioxidants (ascorbic acid, ${\alpha}$-tocopherol, BHT, BHA) at $40^{\circ}C$. The skin retention of RP in crystalline formulations was approximately $5.3{\sim}6.4$ times greater than that of o/w cream formulation. Incorporation of RP into cubic liquid crystalline phase of monoolein effectively stabilized the RP and worked as excellent topical vehicle for RP. Liquid crystalline phase is considered to be suitable formulation for RP for topical delivery system as a stabilizer and permeation enhancing agent.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권12호
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• pp.593-598
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• 2001

Transient liquid phase processing was investigated to decrease processing temperatures while maintaining useful piezoelectric properties in the lead zirconate titanate (PZT) system. Niobium oxide$(Nb_2O_5)$ modified crystalline PZT (PZTN) powder was combined with lead silicate $(PS; PbO-SiO_2)$ glass powder and crystalline titania, zirconia, and niobia. Firing above the melting temperature of the lead silicate $(PS; Tm \risingdotseq\; 714^{\circk}C)$ resulted in liquid phase densification of the PZTN followed by dissolution of the titania, zirconia, and niobia into the liquid phase, and crystallization of additional PZTN. The addition of crystalline titania, zirconia, and niobia to react with the lead oxide from the lead silicate phase resulted in an increase in the dielectric and Piezoelectric properties.

• 대한화장품학회지
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• 제30권2호
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• pp.279-294
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• 2004

본 연구는 화장품에서 사용되는 액정기술에 대하여 기술하였다. 액정이란 고체와 액체의 중간 상태에 존재하는 다양한 형태의 구조를 액정이라 한다. 계면활성제의 높은 농도에서 여러 가지 액정 상이 형성된다. 결정과 같이 분자배열이 규칙적이지는 않지만, 액체 상보다는 비교적 규칙적인 상태를 액정 또는 메조페이스(meso-phase)라고도 말한다. 일반적으로 화장품에서의 액정기술의 종류, 새로운 액정기술에 대하여 설명하였으며, 액정을 만드는 방법에 대하여도 자세히 기술하였다. 특히, 액정을 형성하기 위한 특별한 유화제의 종류에 대하여도 소개하였다 액정을 형성하기 위한 대표적인 원료는 수소첨가 레시친, 세라마이드, 디팔미토일하이드록시프롤린, DEA-세틸포스페이트, 제미니형 계면활성제가 있다. 액정의 형성을 관찰하기 위하여 편광 현미경을 사용하였으며, 가장 잘 나타나는 범위는 400배, 600배, 1,000배에서 잘 나타났다. 또한 액정이 가장 잘 만들어지는 droplet 입자크기는 1-10$\mu\textrm{m}$이었다. 임상 결과로서, 비타민 B$_{5}$의 액정에 대하여 피부 보습효과를 측정한 결과 일반 에멀젼보다 우수한 결과(20% 이상)를 보였다(ANOMA t-test, p '||'&'||'lt; 0.05).

• 한국응용과학기술학회지
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• 제21권1호
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• pp.31-36
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• 2004

Liquid crystalline phases were formed from acylglutamate; polyglyceryl-10 myristate and glycerine mixture and they were used as a base material for preparing an O/W emulsion. When an oil phase is added into the liquid crystalline phases, it was inserted into the dispersed liquid crystal droplets rather than stayed outside the liquid crystals, which can be known by the fact that the size of liquid crystal droplets increases with the increasing oil phase content. Along with the increase in the droplet size, the complex modulus increases from 100 to 350 pascals and the loss angle decreases from 60 to 24 degrees, from which it can be known that the increase in the internal phase volume results in the increase in the elastic property of oil in liquid crystalline-phases (O/LC). When the water phase was lastly added into the O/LC phase, the emulsification occurred to form a O/W emulsion and the averaged particle size of the O/W emulsion changes from 22.5nm to 538nm with the addition of water phase. The results from the droplet size measurements and stability tests under accelerated conditions such as high temperature show that the obtained O/W emulsion is very consistent with time.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1165-1171
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• 2010

The lyotropic mesomorphism of lamellar liquid crystalline phase was examined by observing the swelling behavior of Distearoylphosphatidylcholine(DSPC) in glycerin and panthenol without water. The lyotropic mesomorphism was examined by using DSC, XRDs and Cryo-SEM. Increase of two polar solvents under non-hydrous condition showed distinctive differences in the lyotropic mesomorphism from forming different anisotropic structures with DSPC. Glycerin did not affect to the crystalline region of lamellar phase, whereas typical swelling mesomorphism was shown in the noncrystalline region. In contrast, panthenol showed some effect on the crystalline region, but common swelling mesomorphism was found in the non-crystalline region. In this case, the isopropyl and propyl groups in panthenol were the main factor to affect to the lipophilic domain in the crystalline region of lamellar phase. Also, it was found that the formation of well-arranged lamellar structure only by introducing glycerin and panthenol as a solvent without water, was possible. These results were confirmed by examination of the swelling mesomorphism of liquid crystal membrane triggered by introducing the two polar solvents.

• Biomolecules & Therapeutics
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• 제16권3호
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• pp.226-230
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• 2008

Monoolein-based cubic liquid crystalline systems were formulated for the local delivery of oregonin and hirsutanonol for the treatment of atopic dermatitis. The liquid crystalline phase and its nanodispersion containing drugs were prepared. The skin permeation and deposition properties of the drugs were examined in normal and delipidized rat skin. The proportion of oregonin (%) deposited in normal skin after topical administration of the drugs in the form of aqueous solution, cubic phase or cubic nanodispersions were $1.53\;{\pm}\;0.46$, $3.62\;{\pm}\;0.17$ and $5.13\;{\pm}\;0.73$, and those of hirsutanonol were $2.46\;{\pm}\;0.02$, $5.44\;{\pm}\;0.27$ and $17.28\;{\pm}\;2.19$, respectively. The greater lipophilicity and thus greater skin affinity of hirsutanonol than oregonin contributed the greater amount of skin deposition. The monoolein-based liquid crystalline phases significantly increased the amount of both drugs permeated and deposited. Approximately 3.2, 2.1 and 3.0 times greater amount of oregonin, and 3.4, 2.1 and 2.2 times greater amount of hirsutanonol were deposited in delipidized skin after administration of each drug in the form of aqueous solution, cubic phase and cubic nanodispersions system, respectively, because of lowered barrier function of the delipidized skin. In this study, the effects of drug property, vehicles type and skin condition on skin deposition and permeation properties of drug were examined and concluded that monoolein-based liquid crystalline systems would be a promising formulation for the local delivery of drugs.

• Elastomers and Composites
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• 제52권3호
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• pp.173-179
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• 2017

Side-chain liquid crystalline polymers having polysiloxane skeletons were synthesized by a thiol-ene reaction, using two kinds of mesogenic groups: a cholesteryl group for induction into a cholesteric liquid crystal phase and a triazomesogenic group for imparting light-sensitivity. All the synthesized polymers were crystalline, except the one with a single cholesteryl group. Crystallinity, glass transition temperature, and melt transition temperature increased with increasing content of the azomesogenic group. The polymer (P-C10A0) with a single cholesteryl group has a cholesteric phase, the one (P-C0A10) with a single azomesogenic group has a smectic phase, and those with both types of mesogenic groups showed both smectic and cholesteric phases. The temperature ranges of the two liquid crystalline phases in the co-polymers were independent of the contents of the two types of mesogenic groups. The rate of photoisomerization of the light-sensitive azobenzene group in the polymer decreased with increasing azobenzene content due to steric hindrance between the azomesogenic groups.