Nanoparticles with Individual Site-Isolated Semiconducting Polymers from Intramolecular Chain Collapse Processes

We present the synthesis of polymeric nanoparticles from single ABA type block copolymers in an intramolecular-chain process to result 3-D architectures that confine a single chain of conducting copolymers. ABA triblock copolymers were prepared from conducting polymers such as fluorene homopolymers and fluorene/thiophene copolymers designed as telechelic macroinitiators to facilitate nitroxide-mediated living free radical polymerization methods. The polymerization with styrene and vinylbenzosulfone cross-linking units led to the desired ABA triblock copolymers with 8:1:8 and 5:1:5 ratios of the polymer copolymer blocks under living free radical polymerization conditions. In an intramolecular chain collapse process the ABA triblock copolymers form well-defined single chain nanoparticles with the confined semiconducting polymer block as core unit via a controlled cross-linking of the benzosulfone unit in the A block copolymer. The photoluminescence measurements illustrate the influence of the molecular weight of the A block to be crucial for the site isolation of the embedded conducting polymer block in the resulting nanoparticles with increased quantum efficiencies of 6%.