Effects of polymer concentration and chain length on aggregation in physically associating polymer solutions

The self-assembly of block copolymers containing rigid blocks have received abiding attention due to its rich phase behavior and potential for use in a variety of applications. In this work, under asymmetric interactions between rod/coil components, the self-assembly of coil/coil/rod ABC triblock copolymers is studied using selfconsistent field of lattice model. In addition to micelles, centrosymmetric lamellae (CSLM), lamellae, perforated lamellae, strips and gyroids, non-centrosymmetric (NCSLM) lamellae and wavy morphologies are observed as stable phases. The phase diagram of interaction between rod and coil components versus the rod fraction is constructed given a fixed interaction between coil components. For intermediate rod fraction, degenerate behavior is observed. NCSLM and CSLM are degenerate structures. It is found that the entropy of chain conformation plays an important role for this rich behavior. A mechanism of the degenerate behavior is proposed in coil/rod block copolymers under noncofinement. This study provides some new insights into the degenerate behavior of block compolymers, which can offer a theoretical reference for related experiments.

Section: Introductionmentioning

confidence: 99%

Self-assembly in rod/coil block copolymers: Degenerate behavior under nonconfinement

Han¹,

Liang²,

Zhang³

2020

“…A lattice model is introduced to self-consistent mean-field theory to treat microphase separation for rod-coil block copolymers [24][25][26]. In our previous papers [10,11,27,28], we have used the SCFT lattice model to study the phase behavior of physically associating polymer solutions. It is found that chain architecture and polymer concentration are important factors which affect the property of temperaturedependent aggregation behavior.…”

Section: Introductionmentioning

confidence: 99%

Self-consistent field theoretic simulations of amphiphilic triblock copolymer solutions: Polymer concentration and chain length effects

Han¹,

Ma²

2014

Using the self-consistent field lattice model, polymer concentrationφ P and chain length N (keeping the length ratio of hydrophobic to hydrophilic blocks constant) the effects on temperature-dependent behavior of micelles are studied, in amphiphilic symmetric ABA triblock copolymer solutions. When chain length is increased, at fixedφ P , micelles occur at higher temperature. The variations of average volume fraction of stickersφ s co and the lattice site numbers N ls co at the micellar cores with temperature are dependent on N andφ P , which demonstrates that the aggregation of micelles depends on N andφ P . Moreover, whenφ P is increased, firstly a peak appears on the curve of specific heat C V for unimer-micelle transition, and then in addition a primary peak, the secondary peak, which results from the remicellization, is observed on the curve of C V . For a long chain, in intermediate and high concentration regimes, the shape of specific heat peak markedly changes, and the peak tends to be a more broad peak. Finally, the aggregation behavior of micelles is explained by the aggregation way of amphiphilic triblock copolymer. The obtained results are helpful in understanding the micellar aggregation process.

“…In this report, a SCFT lattice model is applied [14][15][16]. In earlier publications, we have used the SCFT lattice model to study the phase behavior of physically associating polymer solutions [5,17,18]. It is established that the temperature-dependent behavior of aggregates is affinitive to chain architecture [5], and the effect of polymer concentration is in a way similar to that of chain architecture [18].…”

Section: Introductionmentioning

confidence: 99%

Effect of polymer concentration and length of hydrophobic end block on the unimer-micelle transition broadness in amphiphilic ABA symmetric triblock copolymer solutions

Han¹,

Ma²,

Ouyang³

2013

The effects of the length of each hydrophobic end block N st and polymer concentrationφ P on the transition broadness in amphiphilic ABA symmetric triblock copolymer solutions are studied using the self-consistent field lattice model. When the system is cooled, micelles are observed, i.e.,the homogenous solution (unimer)-micelle transition occurs. When N st is increased, at fixedφ P , micelles occur at higher temperature, and the temperature-dependent range of micellar aggregation and half-width of specific heat peak for unimer-micelle transition increase monotonously. Compared with associative polymers, it is found that the magnitude of the transition broadness is determined by the ratio of hydrophobic to hydrophilic blocks, instead of chain length.Whenφ P is decreased, given a large N st , the temperature-dependent range of micellar aggregation and halfwidth of specific heat peak initially decease, and then remain nearly constant. It is shown that the transition broadness is concerned with the changes of the relative magnitudes of the eductions of nonstickers and solvents from micellar cores.