Radical thiol-yne chemistry on diphenylacetylene: selective and quantitative addition enabling the synthesis of hyperbranched poly(vinyl sulfide)s.

A powerful variation of traditional radical thiol-yne reaction with diphenylacetylene (DPA)-based starting materials leading to the quantitative and selective formation of the corresponding vinyl sulfides is reported. A variety of different thiols are shown to undergo reaction with DPA and the influence of their structure on reactivity is studied. The results obtained from the model reactions are then used to guide the efficient synthesis of hyperbranched poly(vinyl sulfide) (hb-PVS) systems by employing a dithiol and a trialkyne in an A2 + B3 approach. The polymers obtained show excellent solubility in common organic solvents and exhibit high refractive indices (e.g., 1.70 at 589 nm). The combined ease of processability and potential for cross-linking make these materials very interesting for applications, such as coatings for optical devices. The selective mono-addition thiol-yne reaction on DPA serves not only as a synthetic method for the preparation of PVS but could also be applied to the general modification of acetylene-containing materials.

Reactive, multifunctional polymer films through thermal cross-linking of orthogonal click groups.

The ability to produce robust and functional cross-linked materials from soluble and processable organic polymers is dependent upon facile chemistries for both reinforcing the structure through cross-linking and for subsequent decoration with active functional groups. Generally, covalent cross-linking of polymeric assemblies is brought about by the application of heat or light to generate highly reactive groups from stable precursors placed along the chains that undergo coupling or grafting reactions. Typically, these strategies suffer from a general lack of control of the cross-linking chemistry as well as the fleeting nature of the reactive species that precludes secondary chemistry. We have addressed both of these issues using orthogonal chemistries to effect both cross-linking and subsequent functionalization of polymer films by mild heating, which results in exacting control of the cross-link density as well as the density of the residual stable functional groups available for subsequent, stepwise functionalization. This methodology is exploited to develop a strategy for the independent and orthogonal triple-functionalization of cross-linked polymer thin-films through microcontact printing.

Multiple nanoscale templates by orthogonal degradation of a supramolecular block copolymer lithographic system.

An orthogonal approach to the creation of multiple nanoscale templates from a single supramolecular block copolymer system is presented. The enabling feature of this strategy is the design of block copolymers that incorporate independent degradation chemistries which permits each block copolymer to be addressed individually and sequentially. By blending a block copolymer containing H-bond donor groups and a UV-degradable domain with the complementary copolymer containing H-bond acceptor groups and an acid-cleavable segment, diverse and tunable nanoporous thin films with different pore sizes and array patterns can be obtained. This robust strategy demonstrates the potential of combining orthogonal chemistry with the inherent tunability of supramolecular systems.