Toward Well-Defined Single-Chain Nanoparticles via Multiple Intra-chain Reactions

Ashley Hanlon

, Ian Martin and Erik Berda. Department of Chemistry,

University of New Hampshire.

Polymer Design Introduction

With the increasing appeal of nanotechnology, there is a demand for development of synthetic techniques for the fabrication of nano-sized objects that allow for precise size control and tailored functionalization. To this end, the collapse or folding of single polymer chains into architecturally defined nanostructures is a rapidly growing research topic in polymer science. Predominately single intra-chain reactions are triggered for single-chain nanoparticle (SCNP) formation.

Currently, there are only a few experimental studies that utilize multiple intra-chain interactions, but researchers are beginning to explore the advantages of this strategy. Progress towards the synthesis of SCNPs through a combination of thermally reversible Diels-Alder reactions and dynamic thiol disulfide exchange reactions are shown. Methacrylate based polymers decorated with pendant protected maleimide groups along with furan or anthracene moieties serve as a means to thermally trigger a reversible intra-molecular crosslink. These types of systems can be used in combination with a pendant pyridyldisulfide for a catalytically triggered dynamic intra-molecular cross-link. Variations on the polymer composition and placement of cross-linkers effect on nanoparticle formation are to be studied .

Sequence Control Studies

The effect of the placement of cross-links within a polymer chain has on SCNP formation has not been deeply investigated in literature. Through the comparison of block versus random polymers the effect of these parameters on the three dimensional structure of SCNPs can be studied.

Random VS.

Block

Single Intra-chain Reactions Scheme 1:

Synthesis of Single-chain Nanoparticles via Thermal and Dynamic Reversible Reactions

Monomer and Polymer Synthesis Summary and Conclusions

SCNP Deprotected Polymer A B C D E F A B,C D G,H G I H F E I A B C E D A F G F,G H B E D C H Much work has been done toward the synthesis of SCNPs with multiple intra-chain reactions, but further synthetic work must be done to obtain reversibly cross-linked SCNPs. The monomer synthesis for this strategy has been achieved and some linear polymers have been synthesized. Future work will be to focus on collapse experiments to use both thermal Diels Alder and thiol disulfide exchange reactions to obtain a reversibly folded nanoparticle.

Polymer 1,20E+00 1,00E+00 T=0 min 8,00E-01 6,00E-01 4,00E-01 2,00E-01 0,00E+00 300 320 340 360 380 400 420

Wavelength (nm)

T=1 min T=2.5

min SCNP 21 23 25 27

Retention Time (min)

29 31

Acknowledgements

The Army Research Office for support through award W911NF-14-1-0177, and NIST for support through award 70NANB15H060

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