Maurice J. Marks

Synthesis and properties of 2,2′-dibromobisphenol A polycarbonate

Abstract The synthesis and properties of 2,2′-dibromobisphenol A polycarbonate (2,2′-DBBA PC) were studied. The monomer, 2,2′-DBBA, was selectively prepared by the direct bromination of bisphenol A in dichloromethane with an inert gas purge. High molecular weight 2,2′-DBBA PC was prepared by interfacial phosgenation of the monomer followed by coupling of the resulting oligomers catalysed by 4- N,N -dimethylaminopyridine. The thermal, tensile, flexural and impact properties of 2,2′-DBBA PC were determined and compared to those of bisphenol A PC, and 1:1 bisphenol A-tetrabromobisphenol A copolycarbonate.)

Density functional theory study on mechanisms of epoxy‐phenol curing reaction

A comprehensive picture on the mechanism of the epoxy‐phenol curing reactions is presented using the density functional theory B3LYP/ 6‐31G(d,p) and simplified physical molecular models to examine all possible reaction pathways. Phenol can act as its own promoter by using an addition phenol molecule to stabilize the transition states, and thus lower the rate‐limiting barriers by 27.0–48.9 kJ/mol. In the uncatalyzed reaction, an epoxy ring is opened by a phenol with an apparent barrier of about 129.6 kJ/mol. In catalyzed reaction, catalysts facilitate the epoxy ring opening prior to curing that lowers the apparent barriers by 48.9–50.6 kJ/mol. However, this can be competed in highly basic catalysts such as amine‐based catalysts, where catalysts are trapped in forms of hydrogen‐bonded complex with phenol. Our theoretical results predict the activation energy in the range of 79.0–80.7 kJ/mol in phosphine‐based catalyzed reactions, which agrees well with the reported experimental range of 54–86 kJ/mol.

Density functional theory study of mechanism of epoxy-carboxylic acid curing reaction

A comprehensive picture on the mechanism of the epoxy‐carboxylic acid curing reactions is presented using the density functional theory B3LYP/6‐31G(d,p) and simplified physical molecular models to examine all possible reaction pathways. Carboxylic acid can act as its own promoter by using the OH group of an additional acid molecule to stabilize the transition states, and thus lower the rate‐limiting barriers by 45 kJ/mol. For comparison, in the uncatalyzed reaction, an epoxy ring is opened by a phenol with an apparent barrier of about 107 kJ/mol. In catalyzed reaction, catalysts facilitate the epoxy ring opening prior to curing that lowers the apparent barriers by 35 kJ/mol. However, this can be competed in highly basic catalysts such as amine‐based catalysts, where catalysts can enhance the nucleophilicity of the acid by forming hydrogen‐bonded complex with it. Our theoretical results predict the activation energy in the range of 71 to 94 kJ/mol, which agrees well with the reported experimental range for catalyzed reactions.

Crosslink Products, Mechanism, and Network Structure of Benzocyclobutene Terminated Bisphenol a Polycarbonates

Studies on crosslinked benzocyclobutene terminated bisphenol A polycarbonates (BCB PC’s) (1) have provided insight into both their crosslinking chemistry and network structure.