Summary: A novel two‐step polymerization strategy allowing the integration of sequence‐defined oligopeptides into synthetic polymers has been demonstrated by the successful synthesis of an oligopeptide‐block‐poly(n‐butyl acrylate) copolymer. The approach utilizes a solid‐phase supported synthesis of an oligopeptide macroinitiator (SPPS) followed by solution‐phase atom transfer radical polymerization (ATRP) initiated by the oligopeptide macroinitiator. The resulting block copolymer exhibited a low $\overline M _{\rm w} /\overline M _{\rm n}$ (1.19) and a controllable $\overline M _{\rm n}$.Poly(n‐butyl acrylate)‐block‐oligopeptide.imagePoly(n‐butyl acrylate)‐block‐oligopeptide.
Straightforward solid-phase-supported synthesis routes were presented to obtain novel oligopeptide-based reversible addition fragmentation transfer (RAFT) agents. These approaches include the coupling of a functional RAFT agent to a resin-bound peptide and the functionality switch of an oligopeptide ATRP macroinitiator into an oligopeptide transfer agent. The solid-phase-supported methods allowed easy purification of the transfer agents, making difficult column purification steps unnecessary. Well-defined conjugates comprising sequence-defined peptides and synthetic polymers could be accessed by applying RAFT polymerization techniques in combination with the peptide macrotransfer agents. Polymerization reactions of n-butyl acrylate were performed in solution, yielding peptide-polymer conjugates with controllable molecular weight and low polydispersities of around 1.1. The peptide-polymer conjugates were characterized using 1 H NMR spectroscopy and size exclusion chromatography (SEC), while the incorporation of the oligopeptide into the synthetic polymer and the preservation of the chirality were shown by circular dichroism (CD) spectroscopy.
Cover: Integration of sequence-defined oligopeptides into synthetic polymers opens a broad scope of possibilities for interfacing synthetic and biological systems. The cover picture features a two-step procedure used to realize such chimera structures, with defined molecular weights and low polydispersity indices. The presented strategy includes the solid-phase supported synthesis of an oligopeptide ATRP macroinitiator, subsequently followed by a solution-phase atom transfer radical polymerization (ATRP).
On the basis of model concepts on physical gas exchange a technique was developed for studying the complex interrelationships existing between the characteristics indicating the suitability of a particular material for ensilage and the specific local conditions for silage making at the farm and in a silo. (degree of anaerobic conditions). Conclusions were drawn as to quantitative relations existing between the thickness of the marginal layers of a silage stack that are subject to losses and the compaction of the silage material and the sealing of the silage top during the periods of filling and storage. On the basis of these considerations limits are given for minimum filling of a silo per day of ensilage as depending on the compactness of the consolidated fresh or wilted silage material. Data are given for silage losses at the edged of the silage stack.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.