Complex single-chain polymer topologies locked by positionable twin disulfide cyclic bridges.

Oligomers containing the peptide sequence cysteine-any-cysteine (CXC) were attached, at specific locations, to a linear chain of polystyrene. The polymer-bound peptide motifs were then oxidized under dilute conditions to afford a complex bio-hybrid bi-cyclic topology via intramolecular twin disulfide bridge formation.

Controlled growth of protein resistant PHEMA brushes via S-RAFT polymerization.

The reversible addition-fragmentation chain transfer polymerization of 2-hydroxyethyl methacrylate (HEMA) from surfaces (S-RAFT) using an R-group-attached chain transfer agent (CTA) is presented. The approach was exploited for the efficient preparation of well-defined PHEMA brushes of up to 50 nm thickness in a controlled fashion without using any cytotoxic catalyst. The chemical composition, morphology and wettability of the samples were assessed by X-ray photoelectron spectroscopy, atomic force microscopy and water contact angle measurements, while the growth kinetics were studied by monitoring the dry thickness via spectroscopic ellipsometry.

Sequence-controlled polymerization using dendritic macromonomers: precise chain-positioning of bulky functional clusters.

A simple strategy to insert functional dendrons at precise positions along a linear polymer backbone is reported. Sequence controlled copolymerization of styrene and polyester dendrons containing a maleimide unit at their focal points was utilized to yield such polymers.

Controlled positioning of activated ester moieties on well-defined linear polymer chains.

The successful sequence-controlled installation of an activated ester using a newly designed monomer pentafluorophenyl 4-maleimidobenzoate is demonstrated. Pentafluorophenyl 4-maleimidobenzoate is kinetically installed at different stages of a nitroxide-mediated polymerization, namely, near the α-chain end and in the middle of a PS chain. In addition, successful installation of apolar and polar functional groups is achieved via post-polymerization functionalization, which demonstrated the versatility of the synthesis of a universal precursor for locally functionalized polymers.

Precision polyelectrolytes.

Charged macromolecules with controlled microstructures were prepared. Well-defined non-ionic precursors were first synthesized by sequence-controlled radical polymerization of tert-butyl 4-vinyl benzoate with various N-substituted maleimides. Afterwards, these macromolecules were hydrolyzed into polyanions.