86
T. A. Deaton et al.
selective solvent is four times to an order of magnitude faster for branched triblock
copolymers with varying degrees of asymmetry compared with the corresponding
diblock copolymer chains [125]. Prhashanna et al. investigated the effects of chain
flexibility and hydrophilic/hydrophobic block ratio on the chain exchange kinetics
between micelles encompassing diblock copolymers in solution [126]. They showed
that the chain exchange mechanism predominantly depends on the chain expulsion/insertion. Multiple rates of chain exchange/expulsion were observed when the
hydrophilic/hydrophobic block ratio is high and the chain is more flexible. This is
due to the increasing number of small micelles, which have faster exchange kinetics.
Prediction of CAC or critical micelle concentrations (CMC) for BCPs are key
for many industrial applications using BCP-based aggregates. Even though these
measurements are formidably expensive, but can be addressed using DPD simulations. Aydin et al. predicted the CAC for two types of ABA triblock copolymers,
Pluronics and Tyrosine-derived PEG5K-b-oligo(DTO-SA)-b-PEG5K block copolymers, in aqueous medium by using DPD simulations [34], and validated their predictions through experiments. As the calculation of the CAC of PEG5K-b-oligo(DTOSA)-b-PEG5K with a long hydrophobic B block is computationally very expensive,
the authors adopted an alternative method. The CAC of triblock copolymers with
shorter hydrophobic blocks and identical hydrophilic blocks was determined. These
values were used to extrapolate the CAC of the triblock copolymers with a specific
hydrophobic block length (Fig. 2b). Using an alternate approach, Vishnyakov et al.
yielded predictions of the CMC of diblock copolymers as a function of the soft repulsion and rigidity parameters which were in quantitative agreement with experimental
measurements of the CMC for typical surfactants [127]. In this study, the DPD interaction parameters were fit to infinite dilution activity coefficients of binary solutions
formed by reference compounds.
The effect of hydrophobic/hydrophilic block ratios on the micellization kinetics
and CAC of specific polymers have also been elucidated by DPD simulations. Chansuna et al. demonstrated that the micelle size increases and the CAC decreases with
increasing PLA/PEG ratio in PLA-PEG-PLA triblock copolymers [128]. The predictions made using DPD simulations were validated via experimental measurements
of the CAC and the hydrodynamics radius of the micelles.
DPD simulation have been invaluable in providing predictions of BCP-based
aggregate morphologies as a function of both solvent selectivity. He et al. examined the formation of complex microstructures from a fully flexible ABA triblock
copolymers assembling in a dilute solution by configuring the solvent selectivity
and exploring a larger parameter space [129]. The study reported a diverse range
of complex microstructures including toroids, spheres, cylinders, Y-like junctions,
vesicles, and disk-like aggregates (Fig. 2d) and observed different pathways for the
formation of these structures. The results of the study enabled the qualitative connection between the DPD interaction parameters and the geometric shape factors. Huang
et al. examined the self-assembly of rod-coil-rod ABA triblock copolymers in a rodselective solvent and demonstrated that the morphologies are dependent upon the
number of BCPs in the aggregates and the length of the B block [130]. Increasing
T. A. Deaton et al.
selective solvent is four times to an order of magnitude faster for branched triblock
copolymers with varying degrees of asymmetry compared with the corresponding
diblock copolymer chains [125]. Prhashanna et al. investigated the effects of chain
flexibility and hydrophilic/hydrophobic block ratio on the chain exchange kinetics
between micelles encompassing diblock copolymers in solution [126]. They showed
that the chain exchange mechanism predominantly depends on the chain expulsion/insertion. Multiple rates of chain exchange/expulsion were observed when the
hydrophilic/hydrophobic block ratio is high and the chain is more flexible. This is
due to the increasing number of small micelles, which have faster exchange kinetics.
Prediction of CAC or critical micelle concentrations (CMC) for BCPs are key
for many industrial applications using BCP-based aggregates. Even though these
measurements are formidably expensive, but can be addressed using DPD simulations. Aydin et al. predicted the CAC for two types of ABA triblock copolymers,
Pluronics and Tyrosine-derived PEG5K-b-oligo(DTO-SA)-b-PEG5K block copolymers, in aqueous medium by using DPD simulations [34], and validated their predictions through experiments. As the calculation of the CAC of PEG5K-b-oligo(DTOSA)-b-PEG5K with a long hydrophobic B block is computationally very expensive,
the authors adopted an alternative method. The CAC of triblock copolymers with
shorter hydrophobic blocks and identical hydrophilic blocks was determined. These
values were used to extrapolate the CAC of the triblock copolymers with a specific
hydrophobic block length (Fig. 2b). Using an alternate approach, Vishnyakov et al.
yielded predictions of the CMC of diblock copolymers as a function of the soft repulsion and rigidity parameters which were in quantitative agreement with experimental
measurements of the CMC for typical surfactants [127]. In this study, the DPD interaction parameters were fit to infinite dilution activity coefficients of binary solutions
formed by reference compounds.
The effect of hydrophobic/hydrophilic block ratios on the micellization kinetics
and CAC of specific polymers have also been elucidated by DPD simulations. Chansuna et al. demonstrated that the micelle size increases and the CAC decreases with
increasing PLA/PEG ratio in PLA-PEG-PLA triblock copolymers [128]. The predictions made using DPD simulations were validated via experimental measurements
of the CAC and the hydrodynamics radius of the micelles.
DPD simulation have been invaluable in providing predictions of BCP-based
aggregate morphologies as a function of both solvent selectivity. He et al. examined the formation of complex microstructures from a fully flexible ABA triblock
copolymers assembling in a dilute solution by configuring the solvent selectivity
and exploring a larger parameter space [129]. The study reported a diverse range
of complex microstructures including toroids, spheres, cylinders, Y-like junctions,
vesicles, and disk-like aggregates (Fig. 2d) and observed different pathways for the
formation of these structures. The results of the study enabled the qualitative connection between the DPD interaction parameters and the geometric shape factors. Huang
et al. examined the self-assembly of rod-coil-rod ABA triblock copolymers in a rodselective solvent and demonstrated that the morphologies are dependent upon the
number of BCPs in the aggregates and the length of the B block [130]. Increasing