Precise Control of Both Dispersity and Molecular Weight Distribution Shape by Polymer Blending

Selective Depolymerization for Sculpting Polymethacrylate Molecular Weight Distributions

Chain-end reactivation of polymethacrylates generated by reversible-deactivation radical polymerization (RDRP) has emerged as a powerful tool for triggering depolymerization at significantly milder temperatures than those traditionally employed. In this study, we demonstrate how the facile depolymerization of poly(butyl methacrylate) (PBMA) can be leveraged to selectively skew the molecular weight distribution (MWD) and predictably alter the viscoelastic properties of blended PBMA mixtures. By mixing polymers with thermally active chain ends with polymers of different molecular weights and inactive chain ends, the MWD of the blends can be skewed to be high or low by selective depolymerization. This approach leads to the counterintuitive principle of the "destructive strengthening" of a material. Finally, we demonstrate, as a proof of concept, the encryption of information within polymer mixtures by linking Morse code with the MWDs before and after selective depolymerization, allowing for the encoding of data within blends of synthetic macromolecules.

A Porphyrin-Based Organic Network Comprising Sustainable Carbon Dots for Photopolymerization

Sustainable carbon dots (CDs) based on furfuraldehyde (F-CD) resulted in a photosensitive material after pursuing the Alder-Longo reaction. The porphyrin moiety formed connects the F-CDs in a covalent organic network. This heterogeneous material (P-CD) was characterized by XPS indicating incorporation of the respective C, N and O moieties. Time resolved fluorescence including global analysis showed contribution of three linked components to the overall dynamics of the excited state. Electrochemical and photonic properties of this heterogeneous material facilitated photopolymerization in a photo-ATRP setup where either CuBr₂ /TPMA, FeBr₃ /Br^- or a metal free reaction setup activated controlled polymerization. Chain extension experiments worked in all three cases showing end group fidelity for activation of controlled block copolymerization using MMA and styrene as monomers. Traditional radical polymerization using a diaryl iodonium salt as co-initiator failed.