Influence of Co-Catalysts and Polymerization Conditions on Properties of Poly(anhydride-alt-epoxide)s from ROCOP Using Salen Complexes with Different Metals.

Proverbio Proverbio,Tritto Tritto,Galotto Galotto,Boggioni Boggioni,Losio Losio

doi:10.3390/polym11071222

Proverbio Proverbio, Tritto Tritto + Show 3 more

Open Access

https://doi.org/10.3390/polym11071222

Copy DOI

Abstract

Cyclohexene oxide (CHO) and phthalic anhydride (PA) have been reacted in the presence of commercial salen–type complexes with different metals Cr (1), Al (2), and Mn (3) in combination with 4-(dimethylamino) pyridine (DMAP), bis-(triphenylphosphorydine) ammonium chloride (PPNCl) and bis-(triphenylphosphoranylidene)ammonium azide (PPNN3) as co-catalysts to obtain alternating poly(PA-alt-CHO)s by ring-opening copolymerization (ROCOP). The effect of different reaction conditions (pre-contact between catalyst and co-catalyst, polymerization time) on the productivity, molecular weight and glass transition temperature has been evaluated. By using a 24 h pre-contact, the aliphatic polyesters obtained were characterized by high molecular weight (Mn > 15 kg/mol) and glass transition temperature (Tg) up to 146 °C; the more sustainable metals Al and Mn in the presence of PPNCl give comparable results to Cr. Moreover, biodegradability data of these polyesters and the study of the microstructure reveal that the biodegradability is influenced more by the type of chain linkages rather than by the molecular weight of the polyesters.

Highlights

Aliphatic polyesters (PEs) are an appealing class of polymers used in a range of applications such as biomedical devices and bulk packaging owing to their excellent properties and general biocompatibility [1,2]
To understand the effect of the polymerization conditions to obtain industrially processable alternating poly(anhydride-alt-epoxide)s with Mn > 11,000 g/mol and Tg > 80 ◦ C, a series of copolymerizations of cyclohexene oxide (CHO) with phthalic anhydride wa performed by the salen-type complexes of three different metals Cr (1), Al (2), and Mn (3) (Scheme 2) in combination with 2-dimethylaminopyridine
Available salen complexes were selected, the chromium complex is one of those most studied in ring-opening copolymerization (ROCOP) and in particular was used by Duchateau for the ROCOP of CHO and anhydrides [34]

Summary

Introduction

Aliphatic polyesters (PEs) are an appealing class of polymers used in a range of applications such as biomedical devices and bulk packaging owing to their excellent properties and general biocompatibility [1,2] They are typically synthesized by ring-opening polymerization (ROP) of lactones and lactides [3,4,5], an excellent controlled polymerization route, which gives polymers with relatively low glass transition temperatures. Of epoxides and cyclic anhydrides (Scheme 1) is becoming an attractive method for the synthesis of PEs [6,7,8,9,10,11,12,13,14,15] It represents an alternative chain-growth route to polyesters with respect to the ring-opening polymerization (ROP) of lactones and an opportunity to broaden the range of materials produced and to overcome some of the limitations of ROP.

Methods

Results

Conclusion