A solid-state NMR study of the 2,15-dimethylhexadecane/urea inclusion compound

Handel, Thomas; Lissner, Falk; Schleid, Thomas; Müller, Klaus

doi:10.1016/j.molstruc.2006.10.029

Cited by 2 publications

(1 citation statement)

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“…Urea inclusion compounds (ICs) with small molecule guests have been made and characterized extensively, and they exhibit specific physical and chemical properties. − These U-ICs typically adopt a hexagonal crystal structure with linear tunnels containing disordered guest molecules. Urea is also able to form inclusion compounds with either hydrophilic or hydrophobic polymers depending on the cross section of the polymer chain. − Three different crystal forms were reported for polymer urea inclusion compounds, and they are hexagonal, ,,, trigonal, , and expanded tetragonal. ,, It has been shown that there is no covalent bonding between the guest polymers and host urea, and the attraction is generally due to van der Waals forces and/or hydrogen bonding.…”

Section: Introductionmentioning

confidence: 99%

Formation of Poly(3-hydroxybutyrate) (PHB) Inclusion Compound with Urea and Unusual Crystallization Behavior of Coalesced PHB

Ravindran

Vasanthan

2015

Macromolecules

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PHB-U-IC has been prepared for the first time by the cocrystallization method. The structure and conformation of poly(3-hydroxybutyrate) (PHB) chains encapsulated in urea (U) channels formed in the PHB-U inclusion complex (PHB-U-IC) were studied by DSC, FTIR, and solid-state NMR spectroscopy. The XRD pattern and FTIR spectroscopy demonstrated that PHB-U-IC takes a different crystal structure than the well-reported hexagonal and trigonal crystal structures of polymer urea inclusion compounds. PHB-U-IC takes an expanded tetragonal crystal structure. The conformation of PHB in the confined environment has been characterized by solid-state NMR spectroscopy and shown that PHB adopts a conformation similar to bulk PHB. The crystallization and thermal properties of as-received PHB and PHB coalesced from its U-IC were compared and demonstrated that the coalesced PHB crystallizes much slower than as-received PHB. Crystallinity of nonisothermally melt crystallized as-received PHB was found to be significantly higher than the crystallinity of nonisothermally melt crystallized coalesced PHB, indicating that coalesced PHB is not easily converted into semicrystalline PHB.

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