The ring-opening polymerization of l,l-lactide with 2-ethylhexanoic acid tin(II) salt as catalyst, and 1-dodecanol as cocatalyst, is investigated at temperatures ranging from 140 to 180 °C and various operating conditions such as different ratios of monomer to catalyst as well as catalyst to cocatalyst amounts. Average molecular weights and byproduct formation have been measured as a function of monomer conversion. A complete kinetic model including intra- and intermolecular transesterifications as well as random chain scission has been developed. All experimental data have been compared with the predictions of the model, which is coherent with the one developed for lower temperature values in a previous work [Yu, Y. C.; Storti, G.; Morbidelli, M. Macromolecules 2009, 42, 8187]. This results in a reliable estimation of the rate coefficients of all involved reactions in a relatively large range of temperatures (130–180 °C).

Ring-opening polymerization of L,L-lactide with various amounts of catalyst, 2-ethylhexanoic acid tin(II) salt, and cocatalyst, 1-dodecanol, at 130 °C in bulk is examined. Monomer-to-catalyst and cocatalyst-to-catalyst molar ratios were changed from 500 to 4000 and from 1 to 600, respectively. In agreement with previous literature, the catalyst concentration is affecting the reaction rate, whereas OHbearing species (such as cocatalyst and impurities) are controlling both reaction rate and polymer molecular weight. A model implementing a living kinetic scheme is first developed and validated by comparison with the experimental results. The rate coefficients of the main reactions (activation, propagation, and reversible chain transfer) have been evaluated. Finally, to predict with accuracy the broadening of the molecular weight distribution, we introduce ester interchange reactions, so-called "transesterifications", into the kinetic scheme, and the corresponding rate coefficient is evaluated.

New ε-caprolactone (CL)-based materials were synthesized. Bulk ring-opening polymerization of ε-caprolactone with 2-hydroxyethyl methacrylate (HEMA) as cocatalyst was carried out to produce various macromonomers composed of HEMA functionalized with 1–10 CL units. All of the HEMA-CL macromonomers have been characterized by size exclusion chromatography (SEC) and 1H NMR. For SEC analysis universal calibration was applied, and Mark–Houwink parameters for poly(HEMA-g-CL3) were obtained. Macromonomers with different CL chain length were polymerized through free radical polymerization, in both batch and semibatch emulsion polymerization to produce CL-based nanoparticles (NPs) with narrow particle size distribution. Various reactions parameters were investigated, namely the type of the emulsifier, the feeding conditions, and the macromonomer chain length. Finally, a simple and qualitative degradation study of selected samples was carried out in order to verify the degradability of these CL-based NPs.

The molecular weight distributions of poly(lactic acid) produced by ring-opening polymerization of L,L-lactide in bulk melt are measured and compared with the ones predicted using a kinetic model accounting for reversible catalyst activation, reversible propagation, reversible chain transfer to co-catalyst and inter-molecular transesterification. The same values of the model parameters as evaluated in previous works are used without any adjustment, i.e. the model is used in fully predictive way. In order to calculate the complete molecular weight distribution, the model equations are solved through two different numerical methods, "direct integration" of the population balances at all values of chain length, and "fractionated moments", where the chains are artificially classified into two different categories depending upon the experienced reaction steps. The accuracy of the molecular weight distributions calculated in the latter case is evaluated by comparison with those computed by solving the model equations with the "direct integration" method. It is found that the "fractionated moments" method provides enough accuracy and much smaller computational effort, thus representing an optimal tool for most modeling applications. Finally, the model predictions are compared with the experimental molecular weight distributions measured experimentally in bulk melt at 130°C and various initial concentrations of catalyst and co-catalyst. The generally good agreement verified between model and experiment after correcting for peak broadening, represents a convincing confirmation of the model reliability.