Synthesis and properties of random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate catalyzed by lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)

Abstract

Random copolymers of 2,2-dimethyltrimethylene carbonate and ethylene carbonate (EC) were synthesized with lanthanide tris(2,6-di-tert-butyl-4-methylphenolate)s [Ln(DBMP) 3 ; Ln ¼ La, Nd, Sm, or Dy] as catalysts, among which La(DBMP) 3 showed the highest activity. Poly(2,2-dimethyltrimethylene carbonate-co-ethylene carbonate)s [poly(DTC-co-EC)]s with high molecular weights were prepared at room temperature and characterized with 1 H-NMR and size exclusion chromatography. The thermal behavior and crystalline properties of the poly(DTC-co-EC)s were analyzed with differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction. The crystallinity and melting temperatures of the poly(DTC-co-EC)s both decreased with increasing EC content in the copolymers. The mechanical properties of these copolymers were also investigated with dynamic mechanical analysis and tensile strength measurements, which revealed that a reduction of the glass-transition temperature and great enhancement of the tensile properties could be achieved with higher EC contents. These improvements in the thermal and mechanical properties indicate potential applications in biomedical research for novel polycarbonates.

Ethylene carbonate/cyclic ester random copolymers synthesized by ring-opening polymerization

“…Zinc-based and organic catalyst systems, distinct from and less air-and moisture-sensitive than the previously established rare earth-based ones, [43][44][45][46][47][48][49][50] also ineffective in the EC homopolymer- a Amount of EC inserted as determined from the crude reaction mixture (refer to Tables 1 and 2). b Glass transition (T g ), melting (T m ), and crystallization (T c ) temperatures as measured by DSC.…”

“…44 The amount of EC incorporated in these various EC copolymers remained in the range 4-31 mol% and affected the thermo-mechanical properties of the copolymers. 47 Degradability of poly(EC-co-CL) and poly(ECco-VL) was also shown to be much improved upon incorporation of EC units along the polyester chain. 44 Thus, although 5CCs such as EC and glycerol carbonate are industrially available in large volumes, their valorization by ROP still remains challenging.…”

“…Also, EC has been successfully copolymerized by ROP with a few other cyclic monomers, namely ε-caprolactone (CL), δ-valerolactone (VL), L-lactide (LLA), and 2,2-dimethyltrimethylene carbonate (DTC). [43][44][45][46][47][48][49][50][51] The initiating systems always 52 involved rare earth complexes: 53 and more rarely sequential 43 copolymerizations were carried out in toluene at room temperature except for LLA (in bulk at 50 °C), over a few hours-to-several days. [43][44][45][46][47][48][49][50] The extent of decarboxylation was observed to depend on the initial EC/ comonomer ratio.…”

“…[43][44][45][46][47][48][49][50][51] The initiating systems always 52 involved rare earth complexes: 53 and more rarely sequential 43 copolymerizations were carried out in toluene at room temperature except for LLA (in bulk at 50 °C), over a few hours-to-several days. [43][44][45][46][47][48][49][50] The extent of decarboxylation was observed to depend on the initial EC/ comonomer ratio. For instance, no CO 2 abstraction was detected in the synthesis of random EC/CL copolymers starting from a EC/CL molar ratio of 60 : 40, while partial (14%) decarboxylation occurred at 70 : 30.…”

Overview: Polycarbonates via Ring-Opening Polymerization, Differences between Six- and Five-Membered Cyclic Carbonates: Inspiration for Green Alternatives

“…The results shows a proven effectiveness for lanthanide complexes as promising initiators for the polymerization and copolymerization of TMC, DMC, and lactones [ 57 , 58 , 59 ]. The main issue facing the wide use of lanthanide complexes in ring-opening polymerization is the two required additional steps, i.e., (1) the preparation of these complexes since they are not commercially available; and (2) the purification process for the complexes [ 60 , 61 ].…”