Ring-opening copolymerization of L-lactide and ɛ-caprolactone in supercritical carbon dioxide using triblock oligomers of caprolactone and PEG as stabilizers

Abstract

In this study, the use of triblock (A-B-A) oligomers of e-caprolactone (e-CL) (A) and PEG400 (B) as stabilizers (SB) for the copolymerization of L-lactide (LLA) and e-CL in supercritical carbon dioxide (scCO 2 ) was investigated. To determine the effect of CO 2 -philic and polymer-philic segments on copolymerization, oligomers with three different average molecular weights (M w ¼2000-6000 Da) were synthesized by changing the PEG400/e-CL ratio. Copolymerizations were confirmed by 1 H-nuclear magnetic resonance (NMR), 13 C-NMR and differential scanning calorimeter data. It was possible to copolymerize LLA and e-CL in scCO 2 without any SB; however, the polymerization yields and average molecular weights were low, and significant aggregate formations were detected. Recipes featuring only 5% SB were successfully applied to reach high polymerization yields of B85% and polymers with average molecular weights greater than 20 kDa. When the polymer-philic segment of the SB increased, both the yield and molecular weight of the copolymer also increased significantly, resulting in white powdery products.

Macroporous silicone biomaterials with modified surface chemistry: Production and characterization

“…The cleaning process also removed all residuals within the matrix as previously reported. 19,20,[25][26][27][28] Here, we have observed a similar behavior, the materials look optically very clear after scCO 2 treatment. More importantly, almost all the NaCl particles were removed from the matrix after salt extraction (Figure 1(b)).…”

“…23,24 In this study and in the previous study, scCO 2 treatment was applied to both the synthesis of biodegradable polymers (lactide and ϵ-caprolactone homopolymer and copolymers) and the preparation of tissue engineering scaffolds. 19,20,25,26…”

“…23,24 In this study and in the previous study, scCO 2 treatment was applied to both the synthesis of biodegradable polymers (lactide and ε-caprolactone homopolymer and copolymers) and the preparation of tissue engineering scaffolds. 19,20,25,26 The porous silicone disks prepared using NaCl crystals in the size range of 250-355 µm with three different salt loadings 60%, 70%, and 80% (w/w) were treated in scCO 2 media. [21][22][23] The average pore sizes and porosities of the silicone scaffolds after scCO 2 treatment are listed in Table 2.…”

Shape Memory Polyurethane Biocomposites Based on Toughened Polycaprolactone Promoted by Nano-Chitosan

“…In order to serve their purpose, biodegradable polymers such as PCL can be used in combination with each other. Moreover, different techniques, such as blending of polymers [ 20 ], copolymerization [ 21 ], fabrication of biocomposite with biofillers [ 22 , 23 ], grafting [ 24 ], crosslinking [ 25 ], etc., can be used to tailor the properties of the PCL based final product. Fabrication of the composite with fillers via blending, in situ polymerization [ 26 ], and reinforcement [ 27 ], is a promising approach to tailor the final product’s properties, such as mechanical strength, toughness, stiffness, biodegradability, and behavior of shape memory.…”

Sustainable synthesis and precise characterisation of bio-based star polycaprolactone synthesised with a metal catalyst and with lipase

“…50,51,45,52 For example, scCO 2 was previously employed as a solvent for the synthesis of linear PCL by ROP of ε-CL using Sn(Oct) 2 or Novozym 435 as a catalyst. 33,50,53,54 In this work, we studied several polyols, including 1,6-hexanediol, glycerol, pentaerythritol and triglycerol, as initiators for the synthesis of star polyol-PCL by ring opening polymerisation. Eventually, we investigated the synthesis of complex star PCL architectures using a renewable polyol core, D-sorbitol, as the initiator, aiming at establishing an environmentally benign process to make biodegradable star D-sorbitol-PCL under mild conditions.…”