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Surface-Initiated ATRP of N-Isopropylacrylamide from Initiator-Modified Self-Assembled Peptide Nanotubes
Peptide−polymer hybrid nanotubes (PPNT) were prepared by a combination of self-assembling functional cyclic peptides and in-situ surface-initiated atom transfer radical polymerization (ATRP). Cyclic peptides that consist of alternating d- and l-amino acids, carrying ATRP initiators in distinct side...
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Published in: | Macromolecules 2006-10, Vol.39 (21), p.7258-7268 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Peptide−polymer hybrid nanotubes (PPNT) were prepared by a combination of self-assembling functional cyclic peptides and in-situ surface-initiated atom transfer radical polymerization (ATRP). Cyclic peptides that consist of alternating d- and l-amino acids, carrying ATRP initiators in distinct side chains, were self-assembled into hollow nanotubes that expose all initiation moieties at the outer surface, thereby forming a cyclic peptide initiator nanotube (CP-ini). The CP-ini nanotubes were dispersed in 2-propanol, and a surface-initiated ATRP reaction has been performed using N-isopropylacrylamide (NIPAM) as monomer, tris[2(dimethylamino)ethyl]amine (Me6TREN) as ligand, and additional sacrificial (model) initiator. The molar mass of the resulting PNIPAM can be well controlled by adjusting the polymerization time (i.e., reaction conversion). The solvent-free height of the PNIPAM−PPNT, as measured by statistical analysis of cross sections of atomic force microscopy (AFM) height micrographs, increases with increasing molar mass of the attached PNIPAM chains in a well-controlled manner. The latter allows for the first time to tailor the outer diameter of self-assembled peptide nanotubes in a very precise way without changes to the primary sequence of the peptide ring. The length of the PNIPAM−PPNT remains almost constant with increasing polymerization time; however, at larger polymerization times, a decrease in absolute number of PPNT is observed, and smaller particles are increasingly present due to a breakup of the PNIPAM−PPNT into smaller peptide−polymer hybrid nanoobjects. |
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ISSN: | 0024-9297 1520-5835 |
DOI: | 10.1021/ma061200j |