No abstract

Novel biodegradable and biocompatible block copolymers of poly(ε-caprolactone) (PCL) and polyphosphoester were prepared in tetrahydrofuran by a two-step sequential ring-opening polymerization of ε-caprolactone and 2-methoxyethyl ethylene phosphate (MOEEP) using aluminum isopropoxide as an initiator. Kinetics studies revealed that homopolymerization of MOEEP initiated by aluminum isopropoxide was in the first-order kinetics with living polymerization characteristics. Polymerization of MOEEP with living PCL macroinitiator obtained by aluminum isopropoxide initiation was efficient in forming block copolymer with narrow molecular weight distribution, which was demonstrated by gel permeation chromatography and 13C NMR analyses. The molecular weight and linear molecular architecture of block copolymer can be controlled by adjusting the molar ratios of monomers and the initiator as well as reaction time. Transesterification side reaction from pendent groups of poly(2-methoxyethyl ethylene phosphate) block, leading to branched molecules, was only observed when the reaction was carried out for relatively long time at high MOEEP conversion. These materials have potential for applications in biomaterials surface modification, drug delivery, and tissue engineering.

New building blocks of cores and periphery groups for organic hole-transporting materials (HTMs) have been paid much attention for recent development in perovskite solar cells (PSCs). In this work, we applied facile synthesis to join a 2,4,6-triarylpyridine building block for new HTMs based on a pyridine core by cheap industrial initial materials. The three small molecules, namely, D104, D105, and D106, were used in the pristine state. To the best of our knowledge, pyridine-cored dopant-free HTMs have not been reported in PSCs. The changing periphery 4-methoxyphenyl and bis(4-methoxyphenyl)amine groups formed different Y-shapes. Under 1 sun conditions, the devices achieved an increased power conversion efficiency (PCE) of 16.28%, 17.40%, and 18.24% for D104, D105, and D106. They displayed great potential with improved stability in inverted planar PSCs. The unencapsulated device in ambient environment (30% RH) based on D104, D105, and D106 retained 33%, 70%, and 75% of the initial PCE after 275 h.