Mols. confined in nanospaces will have distinctly different properties to those in the bulk state because of the formation of specific mol. assemblies and conformations. We studied the chain conformation and dynamics of single polystyrene (PSt) chains confined in highly regular one-dimensional nanochannels of a porous coordination polymer [Zn2(bdc)2ted]n (I) (bdc = 1,4-benzenedicarboxylate, ted = triethylenediamine). Characterization by two-dimensional (2D) heteronuclear 1H-13C NMR gave a direct demonstration of the nanocomposite formation and the intimacy between the PSt and the pore surfaces of I. Calorimetric anal. of the composite did not reveal any glass transition of PSt, which illustrates the different nature of the PSt encapsulated in the nanochannels compared with that of bulk PSt. From N2 adsorption measurements, the apparent d. of PSt in the nanochannel was estd. to be 0.55 g cm-3, which is much lower than that of bulk PSt. Results of a solid-state 2H NMR study of the composite showed the homogeneous mobility of Ph flipping with significantly low activation energy, as a result of the encapsulation of single PSt chains in one-dimensional regular cryst. nanochannels. This is also supported by mol. dynamics (MD) simulations.
Uemura, T., Horike, S., Kitagawa, K., Mizuno, M., Endo, K., Bracco, S., et al. (2008). Conformation and Molecular Dynamics of Single Polystyrene Chain Confined in Coordination Nanospace. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 130(21), 6781-6788 [10.1021/ja800087s].
Conformation and Molecular Dynamics of Single Polystyrene Chain Confined in Coordination Nanospace.
BRACCO, SILVIA;COMOTTI, ANGIOLINA;SOZZANI, PIERO ERNESTO;
2008
Abstract
Mols. confined in nanospaces will have distinctly different properties to those in the bulk state because of the formation of specific mol. assemblies and conformations. We studied the chain conformation and dynamics of single polystyrene (PSt) chains confined in highly regular one-dimensional nanochannels of a porous coordination polymer [Zn2(bdc)2ted]n (I) (bdc = 1,4-benzenedicarboxylate, ted = triethylenediamine). Characterization by two-dimensional (2D) heteronuclear 1H-13C NMR gave a direct demonstration of the nanocomposite formation and the intimacy between the PSt and the pore surfaces of I. Calorimetric anal. of the composite did not reveal any glass transition of PSt, which illustrates the different nature of the PSt encapsulated in the nanochannels compared with that of bulk PSt. From N2 adsorption measurements, the apparent d. of PSt in the nanochannel was estd. to be 0.55 g cm-3, which is much lower than that of bulk PSt. Results of a solid-state 2H NMR study of the composite showed the homogeneous mobility of Ph flipping with significantly low activation energy, as a result of the encapsulation of single PSt chains in one-dimensional regular cryst. nanochannels. This is also supported by mol. dynamics (MD) simulations.
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