Synthesis and Characterization of Epoxidized Styrene‐Butadiene Block Copolymers as Templates for Nanostructured Thermosets

Abstract

Summary: A wide range of epoxidized styrene‐block‐butadiene block copolymers were synthesized using hydrogen peroxide in the presence of an in situ prepared methyltrioctylammoniumtetrakis(diperoxotungstate)phosphate as the catalyst system in a water/dichloroethane biphasic system. 1H NMR and FT‐IR spectra revealed that the epoxidation procedure led mainly to 1,4‐epoxidized butadiene units. GPC analysis showed that epoxidation changed the copolymer architecture into stars with fewer arms. The copolymers showed two glass transition temperatures in accordance with the phase separation for block copolymers and, as revealed in AFM images, the self‐assembly takes place on a nanometer scale. Moreover, epoxidized styrene‐butadiene (SB) copolymers showed improved miscibility with epoxy monomers leading to self‐assembled nanostructures in the uncured state. This allows them to be used as templates for nanostructured resins.TM‐AFM phase images for: a) 40 mol‐% epoxidized copolymer (scale bar = 300 nm); b) uncured blend containing 50 wt.‐% DGEBA in 50 mol‐% epoxidized copolymer (scale bar = 1 μm), after annealing at 80 °C in vacuum for 3 h.imageTM‐AFM phase images for: a) 40 mol‐% epoxidized copolymer (scale bar = 300 nm); b) uncured blend containing 50 wt.‐% DGEBA in 50 mol‐% epoxidized copolymer (scale bar = 1 μm), after annealing at 80 °C in vacuum for 3 h.

Synthesis and Characterization of Nanostructured Blends of Epoxy Resin and Block Copolymers

“…In consistence with the literature works (such as Serrano et al 2004, Liu et al 2009, 2009a, nanostructured morphologies were observed by transmission electron microscopy (TEM) and X-ray analysis (Adhikari et al 2012, in preparation).…”

“…literatures (Serrano et al 2004& Antonietti et al 1996. One gram of the BCP was dissolved in 10 millilitre of dichloromethane in 100 millilitre three-necked round bottom flask equipped with a magnetic stirrer, thermometer and maintained under inert atmosphere.…”

“…These structures may be applicable for several useful purposes such as in nanoreactors, nanofilters, nanofoamed membranes etc. These are being studied for applications in microelectronics, combinatorial science and nanotube fabrication (Serrano et al 2004). Block copolymers are widely used as templates for generating nanostructured epoxy or phenolic resins with long-range order in both uncured and cured states (Serrano et al 2006).…”

“…Later, Liu et al (2009Liu et al ( , 2009aLiu et al ( & 2010 have shown that nanostructured PEO-PEP/epoxy resins provide improved fracture toughness depending on their morphology. Recently, Serrano et al (2004) and Ocando et al (2010) epoxidized styrene-block-butadiene (SB) or styrene-blockbutadiene-block-styrene (SBS) block copolymers, respectively, as templates for nanostructured thermosets. Serrano et al (2004) found that the epoxidation procedure improves the miscibility of the copolymers with the epoxy resin.…”

“…Recently, Serrano et al (2004) and Ocando et al (2010) epoxidized styrene-block-butadiene (SB) or styrene-blockbutadiene-block-styrene (SBS) block copolymers, respectively, as templates for nanostructured thermosets. Serrano et al (2004) found that the epoxidation procedure improves the miscibility of the copolymers with the epoxy resin. Also the curing behavior and final properties of nanostructured thermosetting systems modified with epoxidized diblock copolymers was studies by Serrano et al (2007).…”