High Refractive Index Polymer Thin Films by Charge-Transfer Complexation.

High refractive index polymers are essential in next-generation flexible optical and optoelectronic devices. This paper describes a simple synthetic method to prepare polymeric optical coatings possessing high refractive indexes. Poly(4-vinylpyridine) (P4VP) thin films prepared using initiated chemical vapor deposition are exposed to highly polarizable halogen molecules to form stable charge-transfer complexes: P4VP-IX (X = I, Br, and Cl). Fourier transform infrared spectroscopy was used to confirm the formation of charge-transfer complexes. Characterized by spectroscopic ellipsometry, the maximum refractive index of 2.08 at 587.6 nm is obtained for P4VP-I2. For P4VP-IBr and P4VP-ICl, the maximum refractive indexes are 1.849 and 1.774, respectively. By controlling the concentration of charge-transfer complexes, either through the halogen incorporation step or polymer composition through copolymerization with ethylene glycol dimethacrylate, the refractive indexes of the polymer thin films can be precisely controlled. The feasibility of P4VP-IX materials as optical coatings is also explored. The refractive index and thickness uniformity of a P4VP-I2 film over a 10 mm diameter circular area were characterized, showing standard deviations of 0.0769 and 1.91%, respectively.

Porous Polymer Films with Tunable Pore Size and Morphology by Vapor Deposition.

The fabrication of porous polymer thin films with precise thickness and morphological control through conventional solvent-based techniques is challenging. Herein, we present a fabrication method for porous polymer thin films based on chemical vapor deposition that provides control over pore size, pore morphology, and film thickness. The porous films are prepared by co-depositing crystallizable porogen molecules with cross-linked poly(glycidyl methacrylate) (pGMA) thin films, which are synthesized by initiated chemical vapor deposition (iCVD). As the porogen is deposited, it crystallizes and phase-separates from the polymer film; simultaneous polymerization of pGMA limits crystal growth, controlling the size of crystals. Using naphthalene as porogen resulted in thin films with pore sizes from 5.9 to 24.2 µm and porosities ranging from 59.4 to 78.4%. Using octamethylcyclotetrasiloxane as porogen, which is miscible with the GMA monomer, drastically reduced the pore dimensions, ranging from 14.4 to 65.3 nm with porosities from 8.0 to 33.2%. The film morphology was highly dependent on the relative kinetics of porogen crystallization, phase separation, and heterogeneous polymerization. The kinetics of these competing processes are discussed qualitatively based on nucleation theory and Cahn-Hilliard theory. Fourier-transform infrared spectroscopy confirmed the retention of the reactive epoxide functionality of glycidyl methacrylate, which can enable further chemical derivatization as required for application in optoelectronics, sensing, separations, and biomedical devices.

[Analysis of an ABO subtype with a novel variation].

OBJECTIVE: To analyze the molecular characteristics of a ABO subgroup. METHODS: The ABO phenotype was determined with the tube method. Exons of the ABO gene were analyzed by Sanger sequencing, and haplotypes of exons 6 and 7 were analyzed by cloning sequencing. RESULTS: By forward typing, the red blood cells showed 3+ agglutination reaction with anti-A and 4+ agglutination with anti-B. A weak reaction with A1 cells and no agglutination reaction with B, O cells by the reverse typing. Sequencing results showed heterozygosity including c.297A>G, c.467C>T, c.526C>G, c.608A>G, c.657C>T, c.703G>A, c.796C>A, c.803G>C, c.930G>A. Cloning sequencing revealed a c.608A>G variant in the A allele compared with the ABO*A1.02. CONCLUSION: A new variant site of subtype A of c.608G variation has been identified.

Dual-doping to suppress cracking in spinel LiMn2O4: a joint theoretical and experimental study.

Electrochemical cycling stabilities were compared for undoped and Al/Co dual-doped spinel LiMn2O4 synthesized by solid state reactions. We observed the suppression of particle fracture in Al/Co dual-doped LiMn2O4 during charge/discharge cycling and its distinguishable particle morphology with respect to the undoped material. Systematic first-principles calculations were performed on undoped, Al or Co single-doped, and Al/Co dual-doped LiMn2O4 to investigate their structural differences at the atomistic level. We reveal that while Jahn-Teller distortion associated with the Mn(3+)O6 octahedron is the origin of the lattice strain, the networking -i.e. the distribution of mixed valence Mn ions - is much more important to release the lattice strain, and thus to alleviating particle cracking. The calculations showed that the lattice mismatching between Li(+) intercalation and deintercalation of LiMn2O4 can be significantly reduced by dual-doping, and therefore also the volumetric shrinkage during delithiation. This may account for the near disappearance of cracks on the surface of Al/Co-LiMn2O4 after 350 cycles, while some obvious cracks have developed in undoped LiMn2O4 at similar particle size even after 50 cycles. Correspondingly, Al/Co dual-doped LiMn2O4 showed a good cycling stability with a capacity retention of 84.1% after 350 cycles at a rate of 1C, 8% higher than the undoped phase.