Molecular thermodynamics model for random copolymer solutions

Chen, Ting; Peng, Changjun; Liu, Honglai; Hu, Ying

doi:10.1016/j.fluid.2005.04.014

Cited by 9 publications

(5 citation statements)

References 23 publications

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“…We also examined the swelling data of PNIPA/PVA copolymer gel particles in water, as shown in Figure . Thermodynamically, the effective reduced interchange energy for a copolymer in a solvent S is expressed as follows:

\begin{matrix} true \\ right {\tilde{ɛ}}^{eff} = x {\tilde{ɛ}}_{A S} + (1 - x) {\tilde{ɛ}}_{B S} - x (1 - x) {\tilde{ɛ}}_{A B} \end{matrix}

where A and B refer to two different polymers and x is the mole fraction of the polymer A. In this work, the subscripts A, B, and S refer to PNIPA, PVA, and water, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…We also examined the swelling data [ 54 ] of PNIPA/PVA copolymer gel particles in water, as shown in Figure 6 . Thermodynamically, the effective reduced interchange energy for a copolymer in a solvent S is expressed as follows: [ 56 ] because fully hydrolyzed PVA is not absorbed in the gel network. The thermodynamic framework proposed in this work requires three kinds of parameters: intermolecular interaction, lattice size, and crosslinking parameters.…”

Section: Resultsmentioning

confidence: 99%

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Swelling Behaviors of Poly(N‐isopropylacrylamide) Nanosized Hydrogel Particles/Poly(vinyl alcohol)/Water Systems: Effect of the Degree of Hydrolysis of PVA

Kim

Choi

Bae

2013

Macro Chemistry & Physics

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Using poly(vinyl alcohol) as a drug model, the swelling behaviors of thermosensitive poly(N‐isopropylacrylamide) gel with various concentrations of PVA are investigated. The swelling ratio in PVA9000 is larger than that of PVA89000 at the same composition because the fully hydrolyzed PVA acts as a steric hindrance. A lattice‐based molecular thermodynamic model is used to obtain interaction parameters and then directly applied to describe the swelling behaviors of the gel. Using only one adjustable parameter, the PVA selectivity can be theoretically predicted and the ternary phase diagrams of PNIPA/water/PVA system can be generated. Lastly, the calculated results are compared with the swelling data for PNIPA/PVA copolymer gel, and are found to be in good agreement with the proposed model.

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\begin{matrix} true \\ right {\tilde{ɛ}}^{eff} = x {\tilde{ɛ}}_{A S} + (1 - x) {\tilde{ɛ}}_{B S} - x (1 - x) {\tilde{ɛ}}_{A B} \end{matrix}

where A and B refer to two different polymers and x is the mole fraction of the polymer A. In this work, the subscripts A, B, and S refer to PNIPA, PVA, and water, respectively.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Swelling Behaviors of Poly(N‐isopropylacrylamide) Nanosized Hydrogel Particles/Poly(vinyl alcohol)/Water Systems: Effect of the Degree of Hydrolysis of PVA

Kim

Choi

Bae

2013

Macro Chemistry & Physics

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“…We find that our values closely match with those calculated using the formulation of Chen and co-workers. 45 At low x and λ (e.g., x ) 6.25% and λ ) 10) B * calculated according to the formulation of Chen yields a value of 0.977 B, which is aphysical because collapse of a copolymer with attractive comonomer unit cannot take place at effective temperatures that are lower than for the corresponding homopolymer. Our approach, however, does not have this problem and yields values of B* > 1.…”

Section: Resultsmentioning

confidence: 99%

Collapse Transition in Random Copolymer Solutions

2006

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We present dynamic Monte Carlo lattice simulations of the coil to globule collapse of single chains of a copolymer comprising monomer units, m and c, wherein there is a net attractive interaction between c-units. As the copolymer is cooled, the solvent quality becomes poorer, and the size of the chain decreases, driven by the net m-m and c-c attractions. The strong c-c attraction increases the overall solvophobicity of the chain relative to a homopolymer and, therefore, copolymers collapse more abruptly and at a higher effective temperature relative to homopolymers. We compare copolymers with homopolymers by rescaling collapse data to the same θ values to account for the effect of overall solvophobicity. This comparison shows that the behavior of copolymers and the corresponding homopolymers is identical as the chain size reduces from high temperatures to the θ value. Beyond θ, copolymers with c-content < ∼50% collapse more abruptly than either homopolymer, after accounting for the difference in overall solvophobicity. Collapse of copolymers containing higher c-content is dominated entirely by the c-c attractions, and these chains behave qualitatively like homopolymers with a higher effective solvophobicity. Analysis of the chain structure during collapse provides a structural reason for the qualitative change in copolymer collapse at low c-content. When such copolymers are cooled below θ, the c-units rapidly aggregate to form an isotropic, compact core surrounded by an anisotropic solvated shell of m-units. The shell densifies as the copolymer is further cooled, but remains anisotropic for the finite chain sizes investigated.

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“…These models provide better description of the experimental phase behavior including those with a lower critical solution temperature, loop and hour-glass type liquid-liquid coexistence curves. Recently, Chen et al [22,23] extended RFT to the random copolymer solutions, Bae et al [24] extend their modified double-lattice model to polymer blend systems.…”

Section: Introductionmentioning

confidence: 99%