Controlled development of pores in polyethylene terepthalate sheet by room temperature chemical etching method

• Published in: Journal of membrane science Vol. 471; pp. 185 - 191
• Main Authors: Chavan, Vivek, Agarwal, Chhavi, Pandey, Ashok K., Nair, J.P., Surendran, P., Kalsi, P.C., Goswami, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-12-2014; Elsevier
• Subjects: Applied sciences; Capillary flow porometry; Chemical etching; Chemistry; Colloidal state and disperse state; Exact sciences and technology; Exchange resins and membranes; Forms of application and semi-finished materials; General and physical chemistry; Membranes; Polyethylene terepthalate; Polymer industry, paints, wood; Porous materials; Technology of polymers; Track-etch membrane; Track-etch membrane; Capillary flow porometry; Chemical etching; Polyethylene terepthalate; Ethylene terephthalate polymer; Polymeric membrane; Pore; Porous material; Room temperature
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2014.07.077

In the present work, a room temperature chemical etching (RTCE) method has been explored for controlled development of pores in the chlorine ions (115MeV) bombarded polyethylene terepthalate (PET) (25μm) sheets. In this pore development method, a mixture of ethanolamine and NaOH is employed. The pore-size distributions in thus formed PET track-etched membranes have been obtained by the capillary flow porometry, and compared with the results of PET track-etched membranes subjected to widely used chemical etching (CE) at elevated temperature. Multiple pore size distributions have been observed with the CE method. However, with RTCE, pores with single narrow pore size distribution have been observed. To further improve the RTCE method, the chlorine ions bombarded PET sheets have been sensitized with UV radiation (254nm) for 1h, and subjected to RTCE. The average pore-size has been found to increase with UV-sensitization without affecting the nature of pore-size distribution, indicating the possibility of formation of the track-etch membranes with different pore sizes. Track etching studies show that both bulk-etch and track-etch rates increase in RTCE with respect to the conventional chemical etching. The ratio of the track-etch rate to bulk-etch rate governs the shape of the pores. The conical shaped pores with small cone angles are observed when track-etch rate is significantly higher than the bulk-etch rate. However, in the present case, VT is observed to be not very much greater than VB (VT/VB<100), showing the formation of double bowl pores or conical pores with large cone angles. This has been confirmed by the FEG-SEM observations.
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•PET based track etch membranes prepared indigenously by 115MeV Cl ions irradiation.•A new room temperature etching method for development of latent tracks is explored.•New method (RTCE) is compared with the conventional etching (CE) method based on NaOH.•RTCE yields single pore size distribution, while CE yields multi-peak distribution.•UV sensitization of PET enhances the etching rate, thereby increasing pore size.