Synthesis and characterisation of thermomesogenic polysiloxanes with 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione units in the main chain

Synthesis, characterization, and properties of novel UV-resistant poly(urethane-imide)/POSS nanocomposite

In this study, a series of hybrid nanocomposites composed of poly(urethane-imide) (PUI), fluoroethylene vinyl ether copolymers, and octa-aminophenyl polyhedral oligomeric silsesquioxane (POSS) were successfully prepared. Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), contact angle analysis, thermogravimetric analysis (TGA), and dynamic mechanical analysis were used to characterize the hybrid nanocomposites, which were found to have excellent thermostability, mechanical strength, and ultraviolet (UV) resistance. The SEM results showed that POSS nanoparticles, at low content level, could disperse homogeneously in the PUI matrix. The TGA results confirmed that the thermostability of the hybrid nanocomposites was significantly improved by the addition of POSS. Moreover, the UV-resistant property of the nanocomposites was evaluated based on the change in mechanical property and weight loss caused by the UV radiation. POSS (5 wt%) achieved the highest efficiency in enhancing the UV resistance of the nanocomposites. After UV radiation, the tensile modulus of the nanocomposite without POSS decreased to 187 MPa, and the mass loss was 7.26%. In contrast, the tensile modulus of the nanocomposite containing 5 wt% POSS increased from 412 MPa to 444 MPa, and the mass loss was only 3.76%.

Synthesis and Spectroscopic Studies of N,N'-dialkyl Derivatives of Antisymmetrical 2H,5H-Dihydropyrrolo[3,4-c]pyrrole-1,4-diones

2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione derivatives (DPP) are chemically stable, fluorescent molecules, known as High Performance Pigments. Preparation of the soluble derivatives of DPPs provides great advantage in designing the optic sensor for new and existing applications and overcoming aggregation problems in solid matrices. For this purpose, the synthesis of antisymmetric DPPs and the formation of new organic dyes through N,N'-dialkylation and their spectroscopic studies have been carried out both in solutions and in solid phase.

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

Research activities in the field of diketopyrrolopyrrole (DPP)-based polymers are reviewed. Synthetic pathways to monomers and polymers, and the characteristic properties of the polymers are described. Potential applications in the field of organic electronic materials such as light emitting diodes, organic solar cells and organic field effect transistors are discussed.

Synthesis and Characterization of Polyrotaxanes based on Cyclodextrins and Viologen-modified Polydimethylsiloxanes

β-Cyclodextrin ( 1 -CD) and 2 -cyclodextrin ( 2 -CD) (hosts) formed inclusion complexes with 4,41-bipyridinium dication derivatives with long chains (guests), in which the substituents on the bipyridinium nitrogen atoms are 1,3-bis(chloromethylphenethyl)-1,1,3,3-tetramethyldisiloxane. The number of 2 -CD molecules threaded onto the polymer chain increases with the length of the guest chain. In contrast, the number of β-CD molecules threaded onto the polymer is approximately 4 corresponding to each molecular chain, due to the repulsive interaction between β-CD and the quaternary bipyridinium units. The complexes were isolated in high yield and characterized by 1H NMR, 13C NMR, X-ray diffraction, thermal and scanning electron micrographs studies. As proven by X-ray analysis, the synthesized polyrotaxanes are crystalline materials with crystalline patterns significantly different from that of native cyclic oligosaccharide. The thermal stabilities of polyrotaxanes are higher than that of the physical mixture between cyclodextrin and the alternating copolymer, denoting the formation of the inclusion complexes. Scanning electron micrographs of polyrotaxanes reveal cubic and linear shapes without a well formed shape. Shape regularity and geometrical regularities in the agglomerating forms can be observed.