Theoretical Insights into the Solubility Polarity Switch of Metal-Organic Nanoclusters for Nanoscale Patterning

Metal-organic nanoclusters(MOCs) are being increasingly used as prospective photoresist candidates for advanced nanoscale lithography technologies. However, insight into the irradiation-induced solubility switching process remains unclear. Hereby, the theoretical study employing density functional theory (DFT) calculations of the alkene-containing zirconium oxide MOC photoresists is reported, which is rationally synthesized accordingly, to disclose the mechanism of the nanoscale patterning driven by the switch of solubility from the acid-catalyzed or electron-triggered ligand dissociation. By evaluating the dependence of MOCs' imaging process on photoacid, lithographies of photoresists with and without photoacid generators after exposure to ultraviolet (UV), electron beam, and soft X-ray, it is revealed that photoacid is essential in UV lithography, but it demonstrates little effect on exposure dose in high-energy lithography. Furthermore, theoretical studies using DFT simulations to investigate the plausible photoacid-catalyzed, electron-triggered dissociation, and accompanying radical reaction are performed, and a mechanism is demonstrated that the nanoscale patterning of this type of MOCs is driven by the solubility switch resulting from dissociation-induced strong electrostatic interaction and low-energy barrier radical polymerization with other species. This study can give insights into the chemical mechanisms of patterning, and guide the rational design of photoresists to realize high resolution and high sensitivity.

Organic Glasses of High Glass Transition Temperatures Due To Substitution with Nitrile Groups

The glass transition temperature (T_g) of a molecular glass depends on its molar mass. However, the nature of intermolecular interactions also plays a major role in both the glass transition temperature and its glass-forming ability. In this context, we report on novel molecular glasses containing nitrile groups and investigate the influence of this highly polar group on T_g and the glass-forming ability. As reference compounds, we studied the thermal properties of synthesized molecular glasses with C-C-bonded phenyl rings. The molar mass of the studied compounds ranges from 341 to 568 g/mol. Despite their relatively low molar mass, glass transition temperatures from 347 K (74 °C) to 471 K (198 °C) were observed. Most of the compounds possess high T_g/T_mratios between 0.7 and 0.8. By introducing highly interacting nitrile groups, the dependence of the molar mass on T_g could be increased by a factor of 2-3.

Triphenylbenzene core based dendritic benzoxazines and their heat-resistant and photoluminescent polymers

A facile and efficient synthetic route to connect 1,3,5-tri( p-hydroxyl-phenyl)benzene (TP) molecules into polymers was introduced. Specifically, a series of triphenylbenzene core based dendritic benzoxazines were synthesized via Mannich reaction using TP, paraformaldehyde, and amine derivatives including n-propylamine, cyclohexylamine, and aniline. The chemical structure of benzoxazines was characterized by nuclear magnetic resonance spectroscopy (proton and carbon nuclear magnetic resonance) and Fourier transform infrared spectroscopy. Thermally ring-opening polymerization of the dendritic benzoxazines yielded the cross-linked polymers. We found that N-substituents had the significant influence on polymerization temperature, glass transition temperature ( Tg), thermal stability, and char yield. Polybenzoxazine with the N-phenyl group exhibited the highest Tg of 276°C, char yield of 70%, and excellent thermal stability (5 and 10% weight loss temperatures at 356 and 411°C, respectively). Photoluminescent analysis indicated that the cross-linked structure did not quench the triphenylbenzene’s photoluminescence, while only the relative photoluminescent intensity of polybenzoxazines reduced compared with TP.