Lucas Caire da Silva

Acyclic diene metathesis polymerization and precision polymers

The history of and major advances in the acyclic diene metathesis (ADMET) reaction are described. Because precise branch identity and frequency can be achieved by ADMET polymerizations of symmetrical α,ω-dienes, polyethylenes with precisely spaced alkyl branches of specified length have been prepared. Investigations of their morphologies and thermal properties have provided valuable insight into the behavior of polyethylene. ADMET preparation of ethylene copolymers and telechelic oligomers, as well as the properties of these materials, is also discussed.

Monitoring crack appearance and healing in coatings with damage self-reporting nanocapsules

Autonomous highlighting of damage in protective polymer coatings allows on-demand maintenance and enables prolongation of the lifetimes of the coated materials. To monitor the entire cycle of damage occurrence and successful healing, one must be able to visualize both processes and display the current health-state of the coating. Herein, we equipped coatings with nanocapsules that can self-indicate their mechanical micro-damage via color development. Hence, whenever the coating was damaged, the capsules broke and highlighted the damaged spot. As a second feature, the color development was reversed and discoloration occurred in the presence of (self-)healing compounds, allowing the user to monitor the healing process. Thus, in the first step, damages were highlighted via color “turn-on” and in the subsequent step a propagating healing reaction “turns-off” the damage indication system to trace the healing reaction and allow monitoring of the entire health cycle.

Large-Scale Preparation of Long-Chain ADMET Synthons

Abstract We report a convenient process with minimal purification to produce large quantities of α,ω-alkenyl alcohols. These reagents are indispensable precursors in ADMET chemistry. Icos-19-en-1-ol, nonacos-28-en-1-ol, and octatriacont-37-en-1-ol were produced effortlessly in large quantities (up to 45 g in a single batch) from undec-10-en-1-ol. By extension of the method, any desired methylene run length in the ADMET precursor can be achieved. GRAPHICAL ABSTRACT

Asymmetric Covalent Triazine Framework for Enhanced Visible-Light Photoredox Catalysis via Energy Transfer Cascade

Complex multiple-component semiconductor photocatalysts can be constructed that display enhanced catalytic efficiency via multiple charge and energy transfer, mimicking photosystems in nature. In contrast, the efficiency of single-component semiconductor photocatalysts is usually limited due to the fast recombination of the photogenerated excitons. Here, we report the design of an asymmetric covalent triazine framework as an efficient organic single-component semiconductor photocatalyst. Four different molecular donor-acceptor domains are obtained within the network, leading to enhanced photogenerated charge separation via an intramolecular energy transfer cascade. The photocatalytic efficiency of the asymmetric covalent triazine framework is superior to that of its symmetric counterparts; this was demonstrated by the visible-light-driven formation of benzophosphole oxides from diphenylphosphine oxide and diphenylacetylene.

Designing conjugated microporous polymers for visible light-promoted photocatalytic carbon–carbon double bond cleavage in aqueous medium

The production of valuable carbonyl compounds directly from alkenes via carbon–carbon double (CC) bond cleavage is a highly important reaction. As a promising alternative to traditional metal-catalyzed thermal reaction conditions, photocatalysis offers an environmentally friendly and sustainable synthetic strategy. However, most photocatalysts used so far were homogeneous, molecular and transition metal-based catalytic systems. Here, we report a structural design strategy of conjugated microporous polymers (CMPs) as a class of metal-free, heterogeneous, stable and reusable photocatalysts for visible light-promoted CC bond cleavage reaction. Via different electron donor and acceptor combinations in the CMP backbone structure, we systematically investigated the structural influence of the CMPs on their optical and electrochemical properties, thereby revealing the structure and performance relationship in the photocatalytic CC bond cleavage reaction. As a result, the CMP with a specific electron donor–acceptor combination containing benzothiazole as a strong electron withdrawing unit and phenyl as a weak electron donating unit was the most efficient photocatalyst. The CC bond in various alkenes, mostly styrene derivatives, could be successfully cleaved, forming aldehydes as a product with high conversion and moderate to high selectivity. The green aspect of the work is demonstrated by the utilization of visible-light, molecular oxygen as a cheap oxidant and water-based reaction medium.

Correction: Unveiling the hyperbolic thermal behaviour of poly(p-phenylene alkylene)s

Correction for ‘Unveiling the hyperbolic thermal behaviour of poly(p-phenylene alkylene)s’ by Nicolas F. Sauty et al., Polym. Chem., 2015, 6, 6073–6082.