Bain Capital (Boston) is planning a $1.6-billion initial public offering (IPO) of Styron, reports say. Bain purchased Styron from Dow Chemical last year, and Dow retains a 7.5% stake. Bain is expected to choose underwriters for the IPO within the next few weeks, the reports say. Bain and Styron have declined to comment on the story, which was first reported by Bloomberg. The chemicals IPO market has been quiet in recent months, with the notable exception of Petronas Chemicals’ $4.1 billion IPO in November. Other recent chemicals IPOs include UK-based AZ Electronic Materials and biotech firms Gevo and Amyris.