Synthesis of a Novel Ladder Poly(azomethine-ester) Based on PET Waste Bottles

In the present investigation, a novel ladder polymer, poly(azomethine ester), was prepared via solution polycondensation polymerization between terephthalic acid and the novel monomer. Terephthalic acid was regenerated from PET waste bottles by saponification process, whereas p-phenylenediamine was obtained via Hoffmann rearrangement method. A novel monomer, namely N,N′-bis(2,5-dihydroxy benzylidene)-1,4-diaminobenzene was prepared from the reaction of 2,5-di-hydroxybenzadehyde with p-phenylenediamine in the ratio of 2:1, respectively. For the first time a solution polycondensation method has been employed for the synthesis of a ladder polymer which is otherwise prepared commonly via Diels-Alder cycloaddition reaction. The synthesized ladder polymer was characterized by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR), elemental analysis (CHN), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results revealed that the ladder polymer possess highly regular ladder like framework, and that most of the ester groups have taken part in the side-by-side polymerization reaction.

UV-curable ladder-like diphenylsiloxane-bridged methacryl-phenyl-siloxane for high power LED encapsulation

A UV curable ladder-like diphenylsiloxane-bridged methacryl-phenyl-siloxane (L-MPS) was synthesized from phenyltrichlorosilane, diphenylsilanediol and methacryloxypropyldimethylmethoxysilane via dehydrochlorination precoupling, supramolecular architecture-directed hydrolysis-condensation and end-capping reactions. The L-MPS has a condensation degree of ∼100%, and can be complete crosslinked by UV curing. XRD, TEM and molecular simulation suggest that the ladder-like molecules are close packed with a periodic distance of ca. 1.2 nm. The L-MPS shows transmittance of 98% and a refractive index of ca. 1.61 at 450 nm. The cured L-MPS with a T_d5% value of 465.5 °C showed excellent anti-yellowing and anti-sulfidation properties. The cured L-MPS film and the encapsulated LED samples were compared with those of Dow Corning OE-6630 and OE-7662. It is believed that the dense nano-ladder unit also contributes to the thermal, gas barrier and even optical properties. L-MPS shows promising potential as a high power LED encapsulant and optical coating for use in harsh environments. This work provides an approach to integrate this novel ladder structure with advanced properties.

UV-curable ladder-like polysiloxane was constructed to integrate high RI (1.61/450 nm) with high thermal stability etc. for high power LED encapsulation.