Polymer diffusion in latex films at ambient temperature

✍ Scribed by Jianrong Feng; Hung Pham; Valentina Stoeva; Mitchell A. Winnik

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 234 KB
• Volume: 36
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199805)36:7<1129::aid-polb4>3.0.co;2-p

✦ Synopsis

Polymer diffusion across interfaces at room temperature (21ЊC) was analyzed by direct nonradiative energy transfer (DET) in labeled latex films. Two model latex polymers were examined: poly(butyl methacrylate) [PBMA, M w Å 3.5 1 10 4 , T g (dry) Å 21ЊC] and a copolymer of 2-ethylhexyl methacrylate with 10 wt % (acetoacetoxy)ethyl methacrylate [P(EHMA-co-AAEM), M w Å 4.8 1 10 4 , T g (dry) Å 07ЊC]. Little energy transfer due to polymer diffusion was detected for the P(EHMA-co-AAEM) latex samples in the dispersed state or dried to solids content below ca. 90%, but above 90% solids, diffusion occurs among particles. For PBMA, diffusion occurs only after the film is dried ( ú97% solids) and aged. In the dry PBMA films, it requires 4-5 days at 21ЊC to reach a significant extent of mixing ( f m Å 0.3-0.4). This corresponds to an estimated penetration depth d app of 30-40 nm and a mean apparent diffusion coefficient (D app ) of 5 1 10 04 nm 2 /s. The corresponding D app value for the dry P(EHMA-co-AAEM) sample is 5 1 10 02 nm 2 /s, and it takes about 25-40 min for this polymer to reach f m of 0.3-0.4 with d app of 20-30 nm.