title: FTIR and molecular mechanics studies of H-bonds in aliphatic polyurethane and polyamide-66 model molecules.
abstract: Model aliphatic polyurethane (APU) hard segment based on 1,6-hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) were prepared. FTIR and molecular mechanics (MM) simulation were used to conduct the systematic studies on APU and polyamide-66 (PA-66) whose sole difference lies in the alkoxyl oxygen. It was found that the introduction of the alkoxyl not only increases the conformations in APU, makes it a possible H-bond acceptor, but also weakens the H-bond between NH and O=C in APU. There are two conformers stably existed in APU with lowest energy, leading to eight H-bond complexes based on NH as donor and (1) O=C as acceptor, and another two complexes based on (2) alkoxyl O and (3) urethane N as acceptors, whereas there is only one stable conformer in PA-66, leading to one H-bond complex. One predominant H-bond complex has been found in APU with probability of about 95%. The simulated results are consistent with the nuNH and nuC=O band shifting in FTIR.
authors.affiliation: School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Wang
authors.forename: Chunxia
authors.initials: C
authors.lastname: Zhang
authors.forename: Xiaohe
authors.initials: X
authors.lastname: Guo
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Ren
mesh_terms: D003198:Computer Simulation; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D009757:Nylons / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D009757:Nylons; D011140:Polyurethanes