Thermodynamics and Phase Behavior of Block Copolymer/Homopolymer Blends with Attractive and Repulsive Interactions

Abstract

Small-angle neutron scattering (SANS) experiments were conducted on a 25 vol % blend of a poly(ethylene-block-head-to-head propylene) copolymer (PE-PP) in polyisobutylene (PIB). PE/PIB and PE/PP chains are incompatible (the Flory-Huggins interaction parameter > 0), while PIB and PP are compatible ( < 0) at low temperatures and incompatible ( > 0) at high temperatures. These interactions lead to an order-disorder transition at 150 ( 5°C and macrophase separation at 251 ( 5°C. The nature of the concentration fluctuations in the homogeneous state (155°C < T < 246°C) was studied by comparing the experimentally determined SANS profiles with theoretical calculations based on the multicomponent random phase approximation (RPA). Order formation at low temperatures is driven by two parameters:PE/PIB and lPP (the statistical segment length of the PP block). The other temperature-dependent parameters drive the system away from the ordering transition. At high temperatures, the RPA predicts microphase separation, while experimental data (neutron and light scattering) indicate macrophase separation. This discrepancy is mainly due to the inability of the RPA to correctly account for the large length scale concentration fluctuations.

Block Copolymer Nanostructures and Their Applications: A Review

“…Since its initial conception, block copolymers lithography has been incontestable using a variety of block copolymers, with analysis primarily specializing in all-organic diblock copolymers. completely different experimental techniques like small angle neutron scattering (SANS) [171][172][173][174][175] , ellipsometry [176] , light scattering [177][178][179] , melting point depress and comparison of solubility parameters . It has been shown both in theory and thru an experiment that χΑΒ has an inverse relationship with temperature, and so lowering the temperature of BCPNs soften favors the reduction of A-B contacts leading to phase-separation.…”

Polymer Blends

“…Also morphological characteristics such as particle size of the dispersed phase, structure homogeneity, character of interfacial layer, existence of micelles or mesophases is an indicator of the compatibilization efficiency (25,29,(40)(41)(42)(43)(44).…”

Effect of random and block copolymer additives on a homopolymer blend studied by small‐angle neutron scattering

“…This multicomponent RPA theory has been successfully used to analyze SANS data from a number of different multicomponent polymeric systems 27–31. For example, Hammouda et al27 studied a ternary polymer blend of PS, deuterated PS, and poly(vinyl methyl ether) for which Flory–Huggins interaction parameters were obtained.…”