No abstract

Radical ring‐opening polymerization (RROP) of cyclic ketene acetals allows for the synthesis of functional and biodegradable polyesters. To gain a better understanding of RROP, kinetic studies of this reaction method are thus essential but still rare. In here we conducted kinetic experiments on RROP of 2‐methylene‐1,3,6‐trioxocan (MTC) for the first time. In line with earlier findings, the kinetic behavior could be distributed into a chain growth, stationary and step growth behavior probably caused by dominating branching and recombination reactions impacting the polymerization with increasing conversion. The impact of reaction conditions, such as monomer concentration, reaction temperature and source of energy input (Oil bath, microwave, UV light) were varied systematically. All of these factors were studied towards their influence on polymerization rate constant, density of branches (DB), polymer dispersity and molar mass. While each of these factors were impacted by the reaction conditions, the DB was only depending on monomer conversion. Elution fractionation of PMTC samples with high conversion proved decreasing DB with increasing molar mass. Altogether, this study gives a holistic insight into the kinetics of MTC under various means of free RROP, paving the way for developing a more hydrophilic polyester with adjustable DB and molecular weight.

In this research, the novel materials based on polyamide (PA), polytetrafluoroethylene (PTFE), and olefinic oil molecules are produced as a solid lubricant in metal‐plastic sliding contacts or sacrificial elements in metal–metal sliding contacts. For these applications, high durability of the compound material combined with low wear is required for long‐term use under high friction and mechanical loads. Earlier studies of IPF have shown that chemical bonding between the polymer matrix and the solid lubricant is mandatory to meet these requirements. For this purpose, the compounds are fabricated by a novel two‐step reactive processing procedure based on radiation‐modified PTFE, which exhibits reactive‐functional groups (COOH) and persistent perfluoroalkyl‐(peroxy)‐radicals (COO·). The PA‐PTFE‐oil‐cb compound materials (cb: chemically bonded) are analyzed by differential scanning calorimetry (DSC) concerning breaking down behavior and Fourier‐transform infrared spectroscopy with regards to the chemical covalent bonding state between the three components. Results of scanning electron microscopy investigations in correlation with DSC show that chemical bonding between PA and PTFE‐oil‐cb leads to a homogeneous distribution of solid lubricant particles in the three various PA matrices. Due to the chemical coupling, the compounds offer almost comparable or improved mechanical properties in the case of toughness compared to non‐modified PA.