Poly(ethylene terephthalate) copolymers containing 5-nitroisophthalic units. I. Synthesis and characterization

Abstract

Poly(ethylene terephthalate‐co‐5‐nitroisophthalate) copolymers, abbreviated as PETNI, were synthesized via a two‐step melt copolycondensation of bis(2‐hydroxyethyl) terephthalate and bis(2‐hydroxyethyl) 5‐nitroisophthalate mixtures with molar ratios of these two comonomers varying from 95/5 to 50/50. Polymerization reactions were carried out at temperatures between 200 and 270 °C in the presence of tetrabutyl titanate as a catalyst. The copolyesters were characterized by solution viscosity, GPC, FTIR, and NMR spectroscopy. They were found to be random copolymers and to have a comonomer composition in accordance with that used in the corresponding feed. The copolyesters became less crystalline and showed a steady decay in the melting temperature as the content in 5‐nitroisophthalic units increased. They all showed glass‐transition temperatures superior to that of PET with the maximum value at 85 °C being observed for the 50/50 composition. PETNI copolyesters appeared stable up to 300 °C and thermal degradation was found to occur in two well‐differentiated steps. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1934–1942, 2000

Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. II. Crystallization studies

“…Apparently, it is the influence of the nitro group on the molecular mobility in the noncrystallized phase that determines the anomalous crystallization behavior displayed by PETNI. In this article, which complements the investigation on these copolyesters initiated in the previous article,4 we report the crystallization and crystal structure of these copolyesters. First, the copolymer chain microstructure is characterized by 13 C NMR in solution for the implications that it has on crystallite building.…”

“…The synthesis and chemical characterization of PET and PETNI copolyesters are described in full detail in the aforementioned article,4 which constitutes the part I of this work. The PETI copolymers examined in this study were kindly provided by Catalana de Polímers, S. L. (El Prat, Barcelona, Spain), and they have been reported to have a random microstructure 10.…”

“…In a previous article,4 we reported the synthesis and chemical characterization of a series of PET copolyesters containing 5‐nitroisophthalic units from 5 to 50 mol %. These novel copolyesters are called poly(ethylene terephthalate‐ co ‐5‐nitroisophthalate) (PETNI), and their chemical structure is depicted in Figure 1.…”

Poly(ethylene terephthalate) copolymers containing nitroterephthalic units. II. Crystallization and conformational studies

“…Copolymerization is the method preferentially used to carry out such modifications, the second comonomer being introduced in minor amounts to preserve the overall pattern of properties of the parent homopolymer 1. Recently, we reported the synthesis and chemical characterization of a series of PET copolyesters containing either 5‐nitroisophthalic or nitroterephthalic units in amounts ranging from 5 to 50 mol % 2, 3. These novel PET copolyesters crystallize with more difficulty as the content of nitrated units increases and show a higher T g than PET.…”

Poly(ethylene terephthalate) copolymers containing nitroterephthalic units. I. Synthesis and characterization

“…This work follows our previously reported article concerning PET copolymers containing 5-nitroisophthalic units. 15 The poly(ethylene terephthalate-co-nitroterephthalate) copolyesters are abbreviated PETNT, with the molar ratio of the two comonomers noted as subscripts, for example, PET 50 NT 50 . The copolymers were synthesized by a two-step melt polycondensation of dimethyl terephthalate (DMT) and dimethyl nitroterephthalate (DMNT) mixtures with ethylene glycol (EG), with tetrabutyl titanate (TBT) as a catalyst.…”