Highly Permeable Ultrafiltration Membranes Based on Polyphenylene Sulfone with Cardo Fragments.

Area of Science:

• Polymer Science and Engineering
• Materials Science
• Membrane Technology

Background:

• Polyphenylene sulfone (PPSU) is a high-performance polymer used in membrane applications.
• Enhancing the mechanical strength and permeability of PPSU membranes is crucial for advanced filtration.
• Cardo fragments are known to improve polymer properties but their incorporation into PPSU for ultrafiltration membranes is novel.

Purpose of the Study:

• To synthesize novel copolymers of polyphenylene sulfone (PPSU) with phenolphthalein (PP) cardo fragments.
• To develop highly permeable flat-sheet ultrafiltration membranes with improved mechanical properties.
• To investigate the effect of cardo fragment concentration on polymer solubility, solution viscosity, and membrane performance.

Main Methods:

• Synthesis of PPSU-PP copolymers.
• Fabrication of flat-sheet asymmetric ultrafiltration membranes.
• Characterization of mechanical strength, polymer solubility, solution viscosity, membrane permeance, and dye rejection.

Main Results:

• Copolymers with cardo fragments exhibited 1.3 times higher mechanical strength than commercial PPSU.
• Increased PP concentration enhanced polymer solubility in aprotic solvents, with maximum solubility at 50 mol.% PP.
• Membrane permeance increased significantly with PP concentration, reaching 85.2 L/(m²·h·bar) at 90 mol.% PP, representing a 1.5-8 times improvement over PPSU.
• High rejection (>99.2%) of Blue Dextran (MW=70,000 g/mol) was achieved.

Conclusions:

• The incorporation of cardo fragments into PPSU is an effective strategy for developing high-performance ultrafiltration membranes.
• The synthesized PPSU-PP copolymers yield membranes with superior permeance and mechanical strength compared to unmodified PPSU.
• These novel membranes demonstrate potential for advanced separation processes requiring high flux and selectivity.