Crystallization of poly(-caprolactone) under nanoparticle confinement Academic Article uri icon

abstract

  • Solid-state 13C-NMR spectroscopy has been used to characterize the conformation of the hydrophobic poly (-caprolactone) core of a nanoparticle having a cross-linked hydrophilic poly(acrylic acid)/polyacrylamide shell. The amphiphilic nanoparticles were synthesized from the diblock copolymer, poly(-caprolactone)121-b-poly(acrylic acid)165 by self-assembly into polymer micelles, followed by cross-linking via condensation reactions between the carboxylic acid groups of the hydrophilic shell and the amine groups of 2,2-(ethylenedioxy)-bis(ethylamine). NMR Experiments performed at -30 on nanoparticles rapidly quenched from 60 show that the core is largely noncrystalline and locally disordered. Heating to 25 results in some crystallization, although far less than that observed for bulk poly(-caprolactone) homopolymer. Storage at -30 results in further crystallization and conversion of most rubbery, mobile regions into more rigid, locally ordered amorphous domains. The absence of dipolar coupling between natural-abundance 13C in the poly (-caprolactone) core of the nanoparticle, and 15N labels dispersed throughout the cross-linked shell show that the interface between core and shell is sharp. The dipolar coupling measurements were accomplished by 13C{15N} rotational-echo double resonance.

published proceedings

  • Helvetica Chimica Acta

author list (cited authors)

  • O'Connor, R. D., Zhang, Q., Wooley, K. L., & Schaefer, J.

citation count

  • 6

complete list of authors

  • O'Connor, RD||Zhang, Q||Wooley, KL||Schaefer, J

publication date

  • November 2002