Polymerization kinetics of rac‐lactide initiated with alcohol/stannous octoate using in situ attenuated total reflectance‐fourier transform infrared spectroscopy: An initiator study
Abstract
rac‐Lactide polymerization kinetics in THF at 72 °C were monitored in real‐time using mid‐infrared ATR‐FTIR spectroscopy, with diamond composite insertion probe and light conduit technology. Monomer concentration as a function of time was acquired using the 1240 cm−1 resonance associated with the COOC stretch. Polymerizations were initiated with either n‐propanol (PrOH), ethylene glycol (EG), trimethylol propane (TMP), or pentaerythritol (PENTA) with the coinitiator stannous octoate (Sn(Oct)2). Polymerizations were found to be reversible at high monomer conversions, with a residual monomer concentration at 72 °C (345 K) of 0.081 M. The polymerizations were internally first‐order with respect to monomer, indicating a constant concentration of propagating centers. For a typical reaction with [rac‐LA]0 = 1.0 M, [PENTA]0 = 1.3 × 10−2 M, and [Sn(Oct)2] = 2.5 × 10−2 M, the first‐order rate constant, kapp was measured as 1.8 × 10−4 s−1. First‐order rate constants were determined to be independent of polymer architecture (i.e., initiator functionality) and proportional to [Sn(Oct)2] for [Sn(Oct)2]0/[ROH]0 ≪ 1, where [ROH]0 represents the initial concentration of initiating hydroxyl groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 797–803, 2009
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 17, 2008
- Source ID
- 10.1002/pola.23196
Entities
People
- Jamie M. Messman
- Robson F. Storey
- Scott J. Moravek
Organizations
- Office of Naval Research