The structures and phase transitions of [NH 3 (CH 2 ) n NH 3 ]MnCl 4 ( n = 2, 3, and 4) crystals were confirmed through X-ray diffraction and differential scanning calorimetry (DSC) experiments. Thermodynamic properties, ferroelastic properties, and molecular dynamics of three crystals were studied as a function of the number ( n ) of CH 2 groups in the alkylene chains. The loss in molecular weight due to a decrease in n marked the onset of the partial thermal decomposition. The thermal decomposition temperature, T d , increased with increasing length of the CH 2 chain. While the ferroelastic twin domain walls for n = 2 and 4 were in the same direction at all temperatures, the domain walls for n = 3 were rotated by 45°, and the direction of extinction in phase II was rotated by 45° with respect to phases I and III. The 1 H and 13 C MAS NMR spectra of the three crystals were recorded as a function of temperature. With increasing length of the CH 2 chain, the 1 H spin relaxation time decreased, indicating that molecular motions were activated. These results provide insights into the thermodynamic properties and structural dynamics of the [NH 3 (CH 2 ) n NH 3 ]MnCl 4 crystals and are expected to facilitate their potential applications.

The thermal- and mechanical-properties and optical transparency of the copoly(amide imide) films with different BPA monomer contents were investigated.

Powder X-ray diffraction patterns of [NH3(CH2)6NH3]CuCl4 at different temperatures.

Although PEI/PAA multilayers are insulators, when used as a p-type buffer layer in organic photodetector, they suppressed the leakage current and also provided a high photocurrent due to the light-assisted tunneling effect.

Poly(amic acid) (PAA) was synthesized from dianhydride 4,4-(4,4-isopropylidenediphenoxy)bis(phthalic anhydride) and diamine bis [4-(3-aminophenoxy) phenyl] sulfone. Colorless and transparent polyimide (CPI) hybrid films were synthesized through thermal imidization after dispersing nanofillers using an intercalation method in a PAA solution. C16-GS and C16-MMT, in which hexadecylamine (C16) was substituted on graphene sheet (GS) and montmorillonite (MMT), respectively, were used as nanofillers to reinforce the CPI hybrid films. These two nanofillers were admixed in varying loadings of 0.25 to 1.00 wt%, and the morphology, thermal properties, and optical transparency of the hybrid films were investigated and compared. The results suggest that the thermal properties of the CPI hybrid films can be improved by adding only a small amount of nanofiller. Transmission electron microscopy results of the CPI hybrid film containing two types of fillers suggested that the fillers were well dispersed in the nano-size in the matrix polymer; however, some of the fillers were observed as agglomerated particles above the critical concentration of 0.50 wt%.

4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) as a dianhydride and bis(3-aminophenyl) sulfone (APS) and bis(3-amino-4-hydroxyphenyl) sulfone (APS-OH) as diamines were used to synthesize two types of poly(amic acid) (PAA). Varying amounts (0–5.0 wt%) of water-soluble poly(vinyl alcohol) (PVA) were mixed with PAA, and the resulting blend was heat-treated at different stages to obtain the colorless and transparent polyimide (CPI) blend films. The synthesized blended film completely removed water-soluble PVA in water. The possibility as a porous membrane according to the pore size varied according to the amount of PVA was investigated. The dispersibility and compatibility of CPI containing APS-OH monomer were higher than those of the APS monomer. This could be attributed to the hydrogen-bonding interactions between the CPI main chains and PVA. Scanning electron microscopy was conducted to characterize the material. The results revealed that the pore size of the CPI blend film increased as the PVA concentration increased. It was confirmed that uniform pores of μm-size were observed in CPI. The thermal stabilities, morphologies, optical properties, and solubilities of two CPIs obtained using APS and APS-OH monomers were investigated and their properties were compared with each other.

Poly(amic acid) (PAA) is prepared by the reaction of dianhydride 4,4′-biphthalic anhydride and diamine bis[4-(3-aminophenoxy)phenyl]sulfone in N,N’-dimethylacetamide. Two types of fillers were dispersed in the as-synthesized PAA via a solution intercalation method; polyimide (PI) hybrid films were synthesized under various heat treatment conditions. Octylamine (C8) was introduced into graphene sheets (C8-GS) and bentonite (C8-BTN), which were then used as nanofillers in the PI hybrid films. The synthesized nanofillers were used in varying amounts of 0.25–1.00 wt% with respect to the matrix PI. The thermal and morphological properties and optical transparency of the hybrid films were investigated and compared for both C8-GS and C8-BTN at varying nanofiller content. The C8-BTN nanocomposite showed superior thermal properties, and optical transparency, and the filler was well dispersed in the PI matrix compared to the C8-GS nanocomposite. The thermal stability of the hybrid films improved upon the addition of small amounts of the nanofiller. However, beyond a certain critical filler concentration, the thermal stability declined. These results were verified through the dispersion of fillers via transmission electron microscopy.

Purpose This paper aims to enhance empirical research on foreign divestment and international relocation by multinational firms are still limited and understudied, although these issues have been a frequent phenomenon and carry important economic implications. Design/methodology/approach The paper investigates the trends of foreign divestment in South Korea and examines firm- and host country-level determinants in total, manufacture and service sectors from 2010 to 2019. Findings Using probit model analysis, the main findings are first, among the firm-level factors, sales revenue and parent firm dummy are shown as negative and significant determinants of foreign divestment especially in manufacturing sector. Second, among the country-level factors, gross domestic product growth rate and regulatory quality that measures perceptions of sound policies that promote private sector development are shown negative and significant determinants of foreign divestment. On the other hand, relationship between the environmental policy stringency and foreign divestment is shown positive and significant. Originality/value The results suggest that these nonfirm-specific characteristics are also important factors in firm decision to divest from the host country.