(41e) Design and Prepare Hyperbranched Polymer Composite Membrane from an Industrial Material-Boltorn W3000

Design
and Prepare Hyperbranched Polymer Composite Membrane from an Industrial
Material-Boltorn W3000

Lin
Wang, Naixin Wang*, Tong Wu, Yue Zhang, Cui Zhao, Shulan Ji*

Beijing
Key Laboratory for Green Catalysis and Separation and Department of Chemistry
and Chemical Engineering, Beijing University of Technology, Beijing 100124, P.
R. China.

Nowadays, hyperbranched polymers (HBPs) have been
widely investigated in membrane fabrication process, due to its unique physical
and chemical properties, such as low viscosity, small molecular weight and
abounding of active terminated groups [1-3]. Herein, a commercially available
HBP, Boltorn W3000, was used as the membrane material, which contains
hyperbranched polyester as the core, grafted by hydrophobic fatty acid chains
(see Fig. 1) [4]. On the basis of the distinctive molecular structure, two
simple but effective approaches were utilized to obtain composite membranes for
nanofiltration (NF) and pervaporation (PV).

Firstly, NF membranes were prepared on the PAN flat
substrate from aqueous W3000 emulsion via a novel one-step self-assembly method
(see Fig. 2). The obtained membrane presents an excellent performance in dye
desalination. The dye (methyl blue) and salt retentions can reach 97.0% and
less than 12.0%, respectively. Meanwhile, the flux of the composite membrane
for dye desalination can reach 55.0 L∙m^-2∙h^-1 under the
operation pressure of 0.5 MPa. In addition, the composite membrane maintained
stable separation performance under different operating conditions and a
long-time running test.

Beside, a simple self-crosslinking strategy was
employed to prepare composite membranes for PV separation of toluene/n-heptane
mixtures. After thermal crosslinking, the hydroxyl and carboxyl groups on
Boltorn W3000 molecules could react at intramolecular and intermolecular to
form a stable dense layer. The separation factor and permeation flux of the
"pore-filling" membrane could respectively reach 5.1 and 63.1 g/(m²h)
(40 ^oC). With respect to the "non-pore-filling" membrane, the
composite membrane with "pore-filling" structure performed considerably stable
separation properties.

Moreover,
as the materials are commercially available and the fabrication process are
facile, the membrane obtained via these two approaches would have great
potential in industrial application.

Keywords: Hyperbranched
polymer; Self-emulsify; Self-crosslinking; Nanofiltration; Pervaporation.

References

[1]       L.
Wang, S. Ji, N. Wang, R. Zhang, G. Zhang and J. Li, One-step self-assembly
fabrication of amphiphilic hyperbranched polymer composite membrane from
aqueous emulsion for dye desalination. J. Membr. Sci., 2014, 452:
143-152.

[2]     N.
Wang, L. Wang, R. Zhang, J. Li, C. Zhao, T. Wu and S. Ji, Highly stable
"pore-filling" tubular composite membrane by self-crosslinkable hyperbranched
polymers for toluene/n-heptane separation. J. Membr. Sci., 2015,
474: 263-272.

[3]     C. Gao,
D. Yan, Hyperbranched polymers: from synthesis to applications. Prog. Polym.
Sci., 2004, 29: 183-275.

[4]     U.
Doma¨½ska, Z. Żołek-Tryznowska, Solubility of hyperbranched polymer, Boltorn
W-3000, in alcohols, ethers and hydrocarbons, J. Chem. Thermodynamics 42(2010)
1304-1309.

Fig. 1 Schematic representation of the
amphiphilic HBP Boltorn W3000 molecular structure.

Fig. 2 Schematic
illustration of the preparation process of cross-linked PAN/Boltorn composite
membrane from aqueous emulsion.

Fig. 3 Schematic illustration
of the preparation process of Boltorn W3000 composite membrane with simple
self-crosslinking strategy.