Cross-Linking, Miscibility, and Interface Structure in Blends of Poly(2-ethylhexyl methacrylate) Copolymers. An Energy Transfer Study

Abstract

We describe the miscibility of blends involving poly(ethylhexyl methacrylate) [PEHMA] latex copolymers using the direct nonradiative energy transfer (DET) technique. When the polymers in both components of a blend are PEHMA homopolymers, we obtain a fully mixed film. When one of the components in the blend is replaced with a PEHMA copolymer containing 5 mol % tert-butylcarbodiimidoethyl methacrylate (tBCEMA), we also obtain a fully mixed film. However, if a PEHMA copolymer containing 11 mol % methacrylic acid (MAA) is mixed with PEHMA homopolymer, the miscibility between the polymers is limited and is reduced further when the amount of MAA is increased to 20 mol %. Using a distribution model for energy transfer, we were able to determine the evolution of the interface thickness with annealing time. The maximum interface thickness attained in these blends decreases from δ ) 15 nm to δ ) 8 nm when the content of MAA in the blends increases from 11 mol % to 20 mol %. A freshly formed solvent-cast film prepared from a 1:1 blend of the PEHMA copolymer containing 11 mol % MAA and the PEHMA copolymer containing 5 mol % tBCEMA exhibits some polymer segregation. This persists in the solid film when the film is annealed for short times (20 min) at 60 °C. Over longer times, mixing of the copolymers occurs and reaches completion. We attribute this increase in miscibility to the formation of graft copolymer, which serves as a compatibilizing agent, through the reaction between the -COOH and -NdCdC-groups. When a film of the same composition is prepared from a blend of the two latex dispersions and annealed, a fully mixed film also results.

In‐line monitoring of immiscible polymer blends in a rheometer with a fiber‐optics‐assisted fluorescence detection system

“…The details of the synthesis are described elsewhere. Nonlabeled PEHMA latex was prepared by Pham 25. Both An‐ and Phe‐labeled PBMA were synthesized by Feng 26.…”

Functional latex and thermoset latex films

“…123 It is the reaction between the -COOH groups of P(EHMA-co-MAA) and the carbodiimide groups of P(EHMA-co-tBCEMA) that promotes miscibility, presumably through graft copoly-mer formation. Full mixing (f m = 1) accompanies complete gelation of the film.…”

Overview of Silica-Polymer Nanostructures for Waterborne High-Performance Coatings

“…FRET can give information on the mixing of polymers labeled with donor and acceptor dyes in a wide range geometries [ 15 , 16 , 17 , 18 ], allowing the experimental determination of dye concentration profiles in complex nanostructured materials [ 19 ]. FRET has been used to study the effects of different factors on the formation of waterborne coatings, such as curing temperature [ 20 ], plasticizers [ 21 ], blending [ 22 ], crosslinkers [ 23 , 24 , 25 ], and the presence of filler particles [ 26 , 27 , 28 , 29 ].…”

“…This three-dimensional network not only reinforces the polymer matrix but also strengthens the interface with other components of the film. However, network formation is only effective if the polymer chains are able to diffuse before the crosslinking reaction takes place, so that film formation depends on the kinetics of both processes [ 23 ]. The balance between the diffusion and crosslinking kinetics has been theoretically modeled by De Gennes [ 6 ] to explain the role of diffusion and crosslinking on the development of the films and their final properties.…”