Search

Poly(amic acid) (PAA) was synthesized using dianhydride 4,4'-oxydiphthalic anhydride and diamine 3,3'-dihydroxybenzidine, and polyimide (PI) hybrid films were synthesized by dispersing organo-mica in PAA through a solution intercalation method. Hexadimethrine-mica (HM-Mica), 1,2-dimethylhexadecylimidazolium-mica (MI-Mica), and didodecyldiphenylammonium-mica (DP-Mica), which were obtained via the organic modification of pristine mica, were used as the organo-micas for the PI hybrid films. The organo-mica content was varied from 0.5 to 3.0 wt% with respect to the PI matrix. The thermomechanical properties, morphology, and optical transparency of the resultant PI hybrid films were measured and compared. Dispersion of even small amounts of organo-mica effectively improved the physical properties of the PI hybrids, and maximum enhancements in physical properties were observed at a specific critical content. Electron microscopy of the hybrid films revealed that the organo-mica uniformly dispersed throughout the polymer matrix at the nanoscale level when added at low contents but aggregated in the matrix when added at levels above the critical content. Structural changes in the organo-mica closely influenced the changes in the physical properties of the hybrid films. All PI hybrid films with various organo-mica contents showed similar optical properties, but that prepared with MI-Mica demonstrated the best thermomechanical properties. All synthesized PI hybrid films were transparent regardless of the type and content of organo-mica used., (© 2024. The Author(s).)

Thermotropic liquid crystalline copolyesters (Co-TLCPs) were synthesized by varying the hydroquinone (HQ) molar ratio from 1-5 with respect to the 2,5-diethoxyterephthalic acid (ETA) monomer. The thermal properties and liquid crystalline mesophases of the synthesized Co-TLCP were investigated. All of the Co-TLCPs synthesized using a HQ molar ratio of 1-5 showed a nematic liquid crystalline phase. Among the Co-TLCPs obtained using HQ in various molar ratios, the most stable physical properties and a clear liquid crystalline phase were obtained when HQ was 4 mol. Among the various Co-TLCPs synthesized, hybrids were prepared using Co-TLCP synthesized with a 1 : 4 = ETA : HQ ratio and organoclay. A 1-10% loading of the organoclay Cloisite 93A was employed per weight of TLCP, and the clay was dispersed using the melt intercalation method. Among the Co-TLCP hybrids, the morphology and thermal properties of the hybrids were investigated according to the changes in the Cloisite 93A in the 1-10 wt% range. In general, the thermal properties were superior when the organoclay loading was 3 wt% and were inferior when the organoclay amount was 5 wt% or more. This result was confirmed by the dispersibility of the clay through transmission electron microscopy., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Cantú syndrome is characterized by congenital hypertrichosis, cardiomegaly, and osteochondrodysplasia and is recognized as a rare syndrome. Although it has previously been reported that the majority of affected individuals have a relatively good prognosis, there are no reports on long-term follow up. Here we report the first case of Cantú syndrome in Korea and the associated changes in overall development with rehabilitation over several months.