The crystallization behavior of poly(ethylene glycol) and poly( l ‐lactide) block copolymer: Effects of block length of poly(ethylene glycol) and poly( l ‐lactide)

Abstract

A series of poly(ethylene glycol)‐poly(l‐lactide) (PEG‐PLLA) di‐, and tri‐block copolymers that consisted of different lengths of PEG and PLLA blocks were synthesized, and the crystallization behavior of PEG and PLLA blocks were investigated. Results demonstrate that PEG and PLLA blocks interact with each other, and the crystallization and melting behaviors of copolymers are dependent on the composition of PEG and PLLA. The crystallization of PEG block is confined by the existence of PLLA block, the more fraction of PLLA, the greater restriction on PEG. However, this confinement is reduced after PEG with the larger molecular weight is incorporated into the copolymers. The PEG acts as a solvent, which reduces the viscosity and enhances the chain mobility of the PLLA. The melting temperature of PLLA block decreases when the PEG length is increasing or when the molecular weight of PLLA is decreasing. With the increase of the molecular weight of the PLLA block, the crystallinity of PLLA firstly increases and then decreases. For the copolymers with different structures and molecular weights of PEG blocks, the crystallinity and melting point of PLLA block exhibit different unique component dependence.

Ternary segmented polyurethanes: morphology and kinetics of the crystallization

“…Further cooling to 40 °C led to PEG crystallization in and around the axialites (Figure 3b) and showed that the PLLA crystalline phase acted as a template for PEG crystallization. Similar effect observed for the others SPU (Figure S9) and reported for PEG/PLLA blends [31] and PEG-b-PLLA [5,9] is attributed to confined PEG crystallization in the PLLA crystalline phase [9][10][11] .…”

“…In PEG-b-PLLA and PEG/PLLA blends, PEG is miscible with PLLA in the molten state and causes a decrease in the viscosity [10] , an increase in the PLLA chains mobility and crystals' growth rate [15,42] . On the other hand, PTMC decreases PLLA mobility in PLLA/PTMC blends and the crystals' growth rate [32] .…”

“…For copolymers, phase separation results in microphases in which crystallization occurs [2,5,8] . One of the most studied block copolymer is poly(ethylene glycol)-b-poly(L-lactide), PEG-b-PLLA, because blocks crystallize [5,9,10] . Moreover, PEG crystallizes in confined environments within the PLLA crystalline structure [8][9][10][11][12][13][14][15] .…”

Fractionated crystallization in semicrystalline polymers

“…been studied, among others, PLLA-b-PCL[118,148,162,233], PEG-b-PLLA[234], poly(-caprolactone-b--caprolactam)[149] and hPN-b-LPE[100].Castillo et al studied PLLA-b-PCL double crystalline diblock copolymers[118]. These copolymers are partially miscible, when cooling from the melt the PLLA block crystallizes first, and at lower temperatures the PCL block crystallizes in the interlamellar regions of PLLA.…”

Biomaterial-Mediated Exogenous Facile Coating of Natural Killer Cells for Enhancing Anticancer Efficacy toward Hepatocellular Carcinoma

“…Thermal and crystallization behaviors of PEG moieties after DSPE PEG -diPEG-LBA synthesis were confirmed by differential scanning calorimetry (DSC) analysis. Materials with a low phase transition temperature can undergo softening within biological temperature range, which may enhance stability of coated cells. Figure S4 presents DSC scans of the bisPEG amine, DSPE PEG -NH 2 , DSPE PEG -diPEG-NH 2 , and DSPE PEG -diPEG-LBA conjugates.…”