Synthesis, characterization, and properties of PCDL aliphatic hyperbranched polyurethane coatings

Abstract

The isocyanate-terminated polyurethane pre-polymer (PPU) was synthesized via the step-growth polymerization approach by using polycarbonate diol (PCDL, Mn 5 2000) and isophorone disocyanate (IPDI) as monomers, dibutyltin dilaurate (DBTDL) as the catalyst. Subsequently, the hyperbranched polyurethane (HBPU) was synthesized by graft copolymerization using PPU, hyperbranched poly(amide-ester) polyol (HPAE) and 1,4-butanediol (BDO). The molecular structure of HBPU was characterized by means of FTIR, 1 H-NMR, and 13 C-NMR. It was observed that HBPU was synthesized as anticipated. The thermal and mechanical properties, the microstructure, and morphologies of the filmed HBPU and LPU (linear polyurethane) were tested, respectively. The filmed HBPU, revealed better thermal stability, and higher T g accompanied with lower viscosity than those of filmed LPU. Additionally, the mechanical experiment showed that the filmed HBPU exhibited enhanced mechanical properties because it contained certain amounts of HPAE. Compared with its linear analog (LPU) specimen, the tensile strength of the filmed HBPU containing 10 wt % HPAE increased by 1.9 times (up to 28.15 MPa), and its elongation at break increased by 1.5 times (up to 543.8%), resulting from the dual effects of the hydrogen bonding and the crosslinking density in the HBPU system. The morphologies of filmed HBPU were characterized by means of WAXD and SEM, which indicated that increasing the content of HPAE lowers the crystallinity of HBPU.Recently, a lot of studies on the application of hyperbranched polymers in PU field have been reported. A series of morphology hyperbranched polyurethane (HB-PU) and hyperbranched shape memory polyurethane (HB-SMPU) has been prepared by Cao and co-workers, 15-18 they found that hard segment content has a significant influence on the properties of PU. Okrasa and co-workers 19,20 studied the molecular dynamics in polyurethane network and molecular relaxations synthesized by hyperbranched polyesters (trade name Boltorn V R ). They found that the macrobiol length had a strong influence on the glass transition and the a-relaxation process correlated with it. Sheth and co-workers 21 observed the structure-property behavior of highly branched pre-polymer (PPU) and its linear analog synthesized with bis (4-isocyanatocyclohexyl) methane and polyether polyol, etc. They drew the conclusion that the tensile strength of the highly branched PPU was lower than that of the linear analog synthesized. The tensile tests of hyperbranched aqueous poly(urethane-urea) (HBAPU) by Liu et al. 22,23 revealed that HBAPU exhibited excellent tensile properties, maximum tensile strength, and higher T g accompanied with lower viscosity.

Effects of the molecular structure on the vibration reduction and properties of hyperbranched waterborne polyurethane–acrylate for damping coatings

“…The peaks at 4.84–5.0 ppm were assigned to the proton chemical shift in the ─OH groups, whereas the hydrogen atom of IPDI resonated at 0–2 ppm. All of these analyses proved that HP was successfully prepared …”

“…This phenomenon demonstrated that the introduced HP improved the thermal stability of the HWPUA films. It was due to the enhanced of compatibility between the hard and soft segments with increasing branching degree . In addition, the thermal stability of the HWPUA films at a 1.5% concentration of HP was lower that of the films at a 1% content of HP.…”

Preparation and Characterization of Self-Colored Waterborne Polyurethane and Its Application in Eco-Friendly Manufacturing of Microfiber Synthetic Leather Base

“…This was probably because the unreacted hydroxyl groups in HPAE-1 strengthened the hydrogen bond interaction of hard segments of polyurethane [ 36 ] and moved the absorption peak of C=O from a high wavenumber to a low wavenumber. The typical absorption band of OH at 3400 cm −1 was not obvious and might have overlapped with the absorption band of N-H [ 37 ]. It was manifested that waterborne polyurethane containing free hydroxyl groups (WPU-H) was synthesized.…”

Synthesis of blocked and branched waterborne polyurethanes for pigment printing applications

“…Hyperbranched shape‐memory polyurethane can be prepared via A 2 + B 3 approach and it offered twofold higher shape‐recovery rate compared with its linear counterpart . Isocyanate‐terminated prepolymer and hyperbranched poly(amide‐ester) polyol were used to synthesize BPU by graft copolymerization, which also showed outstanding thermal and mechanical properties …”