Premium
From Nongelating to Gelating: Synthesis and Structural Self‐Assembling Property Relationships of a Homologous Series of Oligo(amide–triazole)s
Author(s) -
Zhang Juntao,
Chow HakFun,
Chan ManChor,
Chow Gary KaWai,
Kuck Dietmar
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201300682
Subject(s) - hydrogen bond , amide , intermolecular force , triazole , chemistry , polymer chemistry , homologous series , differential scanning calorimetry , oligomer , molecule , crystallography , organic chemistry , physics , thermodynamics
A homologous series of oligo(amide–triazole)s (OAT) [ OAT‐CO 2 H‐2 n and OAT‐COPrg‐(2 n +1) ] with an increasing number of primary amide (CONH) and triazole hydrogen‐bonding functionalities was prepared by an iterative synthetic procedure. It was found that their self‐assembly and thermoreversible gelation strength had a strong correlation to the number of hydrogen‐bonding moieties in the oligomers. There also existed a threshold value of the number of CONH units, above which all the oligomers became organogelators. Hence, oligomers with ≤4 CONH units are devoid of intermolecular hydrogen bonding and also non‐organogelating, whereas those that contain >4 CONH units show intermolecular association and organogelating properties. For the organogelators, the T gel value increases monotonically with increasing number of CONH units. On the basis of FTIR measurements, both the CONH and triazole CH groups were involved in the hydrogen‐bonding process. A mixed xerogel that consisted of a 1:1 weight ratio of two oligomers of different lengths ( OAT‐CO 2 H‐6 and OAT‐CO 2 H‐12 ) was found to show microphase segregation according to differential scanning calorimetry, thus indicating that oligomers that bear a different number of hydrogen‐bonding units exhibited self‐sorting to maximize the extent of intermolecular hydrogen bonding in the xerogel state.