Thermodynamic Interactions in a Model Polydiene/Polyolefin Blend Based on 1,2-Polybutadiene

Abstract

Thermodynamic interactions in polydiene/polyolefin blends composed of 1,2-polybutadiene (1,2-PBD) and fully saturated (with deuterium) 1,2-PBD were explored with small-angle neutron scattering (SANS). Two methods were employed to extract the temperature dependence of the Flory− Huggins interaction parameter, χ, from SANS data obtained in the single-phase region. First, Zimm analysis was conducted employing data obtained at low scattering angles, providing a model-independent method of characterizing χ. Next, the random phase approximation was fit to the full angle-dependent absolute scattering intensity. The χ parameter for 1,2-PBD/ saturated 1,2-PBD was found to be large in magnitude at low temperatures and exhibited a strong temperature dependence. The experimentally measured χ, at high temperatures, was in agreement with predictions of solubility parameter theory based on PVT properties of the individual components. The large and strongly temperature-dependent χ parameter of the 1,2-PBD/saturated 1,2-PBD mixture is an attractive feature enabling facile material processing and is in stark contrast to behavior observed in more traditionally studied polyolefin/polyolefin and polydiene/polydiene pairs.

Investigating the Effect of Added Salt on the Chain Dimensions of Poly(ethylene oxide) through Small-Angle Neutron Scattering

“…While high scattering from pure deuterated samples has been seen previously 23 , the reason for this observation has not been fully established. We believe that the scattering intensity of the pure deuterated sample is higher than that of the saltcontaining samples due to its higher concentration of dPEO, the main contributor to high intensity scattering.…”

Effect of Copolymer Composition on Thermodynamic Interactions in Blends Containing a Diene–Olefin Copolymer and a Polyolefin

“…We observed an unusually large and strongly temperature-dependent χ in blends composed of 1,2-PBD and PEE. 18 Similarly, prior studies reported strong interactions, with strong temperature dependencies, in blends of 1,4-polyisoprene (1,4-PI) and poly(ethylene-alt-propylene) (PEP, i.e., saturated 1,4-PI) and blends of 1,4-PI and PEE. 19,20 The effect of copolymer composition on interactions in blends containing a copolymer of diene−olefin units mixed with the corresponding polyolefin has been underexplored, in some part due to the anticipated large repulsive thermodynamic interactions in these blends.…”

“…1,2-PBD and 1,4-PI were synthesized by anionic polymerization, as described previously. 18 Briefly, the monomers, 1,3 butadiene (≥99%) and isoprene (≥99%), were purified over calcium hydride (CaH 2 , ≥95%), followed by purification with sec-butyllithium (1.4 M in cyclohexane) for 1,3 butadiene and n-butyllithium (2.0 M in cyclohexane) for isoprene, employing vacuum distillation. The polymerization initiator was sec-butyllithium (1.4 The molar ratio of DIPIP/initiator was optimized at 10:1 to achieve 1,2 content higher than 99%.…”

“…Weightaverage molecular weight (M w ) and dispersity (Đ) were characterized through GPC using tetrahydrofuran (THF) as the mobile phase at 30 °C, as detailed previously. 18 The flow rate was 1 mL/min with 100 μL injection volume. Polymer concentration varied from 1 to 5 mg/mL, depending on the molecular weight.…”

Blends of Polyisoprene with Model Styrene–Olefin Copolymers: Mixing Energetics in Blends versus Block Copolymers

“…Elastomeric polymer mixtures constitute an important class of polymer blends due to their widespread use in adhesives, tires, sealants, and so forth. , While several studies have been made on the mixing behavior of elastomers where the component polymers are from the same chemical group (polydiene/polydiene or polyolefin/polyolefin systems), ,,− far fewer systematic studies exist on blends of polymers across these chemical groups (polydiene/polyolefin systems) owing to their relative incompatibility. − In our earlier work on PI–hSBR block copolymers, we showed that random incorporation of small amounts of styrene (S) into a hydrogenated polybutadiene (hPB) (model polyolefin) block enhances its compatibility with PI (reduces X ) significantly. We also showed that the experimental variation in X with the styrene content is well-explained by a simple mixing treatment, the CEM ,,,− where φ S is the volume fraction of styrene in the hSBR block and X i – j are the pair-wise interaction energy densities independently determined from block copolymers.…”