Translating Simulated Chain Length and Molar Mass Distributions in Chain‐Growth Polymerization for Experimental Comparison and Mechanistic Insight

The molar mass distribution (MMD), which is also known as the molecular weight distribution (MWD), is a key molecular property for a polymerization process, as it determines polymer strength and polymeric material deformation. Several MMD and related chain length distribution (CLD) representations are however used interchangeably, often leading to biased conclusions. Herein it is highlighted how the most interesting simulated CLD/MMD representations, i.e., the number, mass, z-based, and logarithmic CLD/MMD, can be translated into each other and how they need to be corrected to facilitate comparison with experimental size exclusion chromatography traces. Their relevance is highlighted by including case studies with increasing complexity in polymer products, addressing first linear, then branched, and ultimately crosslinked systems. For illustration purposes, the case studies are restricted to chain-growth polymerization, including free radical polymerization, cationic ring-opening polymerization, and free radical-induced grafting. All model parameters are taken from literature and kinetic Monte Carlo tools are utilized. Guidelines are also provided for both the experimentalist and modeler to maximize the reliability of CLD/MMD reporting in future kinetic studies.