Universality in Solution Properties of Polymers in Ionic Liquids

Abstract

Knowledge of the interaction parameters for polymers in different solvents is crucial for exploring the viscoelastic properties and processing capabilities of polymer solutions. Here, we apply a scaling theory of semidilute polymer solutions to quantify the solution properties of cellulose, poly(ethylene oxide), poly(methyl methacrylate), and poly-(acrylonitrile-co-itaconic acid) in different ionic liquids. The starting point of our approach is a scaling relationship between the solution correlation length ξ = lg ν /B and the number of repeat units g in a correlation blob for polymers with a repeat unit projection length l, chain segment fractal dimension 1/ν, and the corresponding interaction parameter B describing polymer−solvent affinity and assuming values B g , B th , and 1 in different solution regimes. In the framework of this approach, we obtain crossover concentrations to the semidilute solution regime, c*, the solution regime of overlapping thermal blobs, c th , and the concentrated solution regime, c**. The method takes advantage of the linear relationship of the specific viscosity η sp with the number of correlation blobs per chain N w /g in the unentangled Rouse regime for polymers with a weight-average degree of polymerization N w . The application of our approach to entangled solutions provides the chain packing number, P e , and completes the set of parameters {B g , B th , and P e } that uniquely describes the static and dynamic solution properties for a given polymer/solvent pair. This approach also allows us to identify a trend relating the B g parameter to the van der Waals volume of the ionic liquid anion, analogous to the Hofmeister series, and to obtain the temperature and solvent type dependence of the polymer excluded volume and Kuhn length.

Brush Gels: Where Theory, Simulations, and Experiments Meet

“…Lastly, the developed framework should allow the use of a combination of mechanical testing in the dry state , and analysis of the concentration dependence of solution viscosity in semidilute solutions of uncross-linked strands − to predict the equilibrium swelling ratio and gel shear modulus. Specifically, these two techniques provide a functional form of the nonlinear shear modulus (eq ) and values of the B parameters, respectively, both of which are required for calculations of the gel modulus and swelling ratio (eqs and ).…”

“…As a polymer network swells in a selective solvent, the network strands adopt the conformations of stretched chains in a semidilute polymer solution as illustrated in Figure . In a semidilute solution, the interactions between monomers are screened on the length scales on the order of the solution correlation length ξ which contains sections of brushes with g ξ backbone monomers − where exponent ν = 0.5 and 0.588 for θ and good solvents, respectively, and l is the monomer projection length. The parameter B characterizes the interactions between a polymer and a solvent and can be written in terms of the excluded volume v s per monomer of the backbone and the Kuhn length, b K,s , of the network strand in a solvent as follows: − The parameter B is equal to B g and B th for scaling exponent ν = 0.588 and ν = 0.5, respectively.…”

“…We begin with a brief overview of the Flory–Rehner , model of brush gels developed in ref . This is followed by derivation of a scaling model − of brush gels which accounts for the renormalization of the Kuhn length of the brush strands in selective solvents and the enhancement of the strands’ elastic response due to their finite extensibility. The model predictions for gel shear modulus dependence on the equilibrium swelling ratio are compared with the results of new coarse-grained molecular dynamic simulations and experimental data for poly­( n -butyl acrylate) (PBA) networks swollen in toluene.…”

Salt Effect on the Viscosity of Semidilute Polyelectrolyte Solutions: Sodium Polystyrenesulfonate

“…Having established the existence of different solution regimes, we can use the approach developed in refs , , and – and briefly described in the Methods section to obtain the corresponding numerical values of the B -parameters (Figure b) and use this information to estimate blob dimensions and crossover concentrations between different solution regimes (Table ). The approach takes advantage of the linear relationship between solution specific viscosity and number of correlation blobs per chain in the Rouse regime which immediately follows from the crossover expression eq by setting N w / N e ≪ 1.…”

Recent Research Progress of Ionic Liquid Dissolving Silks for Biomedicine and Tissue Engineering Applications

“…ILs are generally composed of large volumes of organic cations supplying positive charge and organic or inorganic anions providing negative charge [ 35 ]. Compared with traditional organic solvents, ILs possess many attractive and unique properties, such as no significant vapor pressure, wide liquid temperature, good conductivity, thermal and chemical stability, and good solubility, as well as designability of structure and characteristics for various materials [ 36 , 37 , 38 , 39 ]. The scientific community is increasingly focusing on the advantages, for instance, the high solubility and stability of ILs for silk regeneration, and its composite preparation with other materials is an effective new strategy to obtain various adjustable properties of biomaterials ( Figure 1 ) [ 40 ].…”