Open AccessEnd-Terminated Poly(urethane–urea) Hybrid Approach toward Nanoporous/Microfilament Morphology
Author(s) -
Rashmi Edachery Veetil,
S. Bhuvaneswari,
Dona Mathew,
Santhosh Kumar Kalamblayil Sankaranarayanan
Publication year - 2022
Publication title -
acs omega
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 0.779
H-Index - 40
ISSN - 2470-1343
DOI - 10.1021/acsomega.1c06888
Subject(s) - polyurea , urea , morphology (biology) , hydrogen bond , materials science , polymer , polymer chemistry , copolymer , crystallography , polyurethane , chemistry , molecule , composite material , organic chemistry , biology , genetics
In the present work, the effect of heteroatomic hydrogen bonding on the properties of -OH/-NH-terminated soft-segment-free polymers, viz , polyurethane (P-UT), polyurea (P-UR), and their hybrid (P-UT-UR), is explored. P-UT was synthesized from phloroglucinol and P-UR was synthesized from 1,3,5-triazine-2,4,6-triamine by employing hexamethylene diisocyanate as a counterpart. P-UT exhibited a spherulitic structure with varying sizes, whereas P-UR displayed a fibrillar structure characteristic as that of crystalline hard segments. The P-UT-UR hybrid exhibited a fine nanospherulitic structure with a high order of interconnectivity. Negative surface skewness values of -0.47 and -0.18 were measured (by AFM) for P-UT and P-UT-UR, respectively, which revealed that the surface is not smooth and is covered with features. Due to the increased H-bonding (-N-H···O-H) in P-UT-UR, its transparency decreased. A block copolymer hybrid of urethane-urea was synthesized, which preferred homoatomic H-bonding, whereas random urethane/urea bridges favored hetreoheteroatom H-bonding. A pentafluorophenyl end-functional hybrid (PFI-P-UT-UR) was synthesized, which displayed filaments of ∼2-3 μm length in contrast to the interconnected nanospherulitic structure observed for P-UT-UR. The self-aggregation and end folding led to the formation of a filament structure. By altering the chemical structure slightly, nano-ordered polyurethanes or their hybrids can be achieved.