Controlled epoxidation of poly(styrene‐b‐isoprene‐b‐styrene) block copolymer for the development of nanostructured epoxy thermosets

Abstract

To be used as templates for nanostructured thermosets, a commercial poly(styrene-b-isoprene-b-styrene) (SIS) block copolymer (BCP) was epoxidized by three different epoxidation procedures. An exhaustive analysis of methodologies using metal catalyzed/hydrogen peroxide, dimethyldioxirane (DMDO), and meta-chloroperbenzoic acid (m-CPBA) was performed to obtain reactive BCPs. The DMDO approach was the best strategy to obtain highly epoxidized SIS BCP (85 mol %) without formation of side products. Careful control in BCP epoxidation by metal catalyzed/hydrogen peroxide and m-CPBA approaches led to a maximum epoxidation degree (ED) of approximately 60 mol % without the formation of side products. The ED by metal catalyzed/hydrogen peroxide strategy could be further increased to 69 mol %, but a significant amount of cross-linking, ring opening, and polymer chain scission reactions were detected by spectroscopic and chromatographic techniques. The miscibility of epoxidized BCPs with diglycidyl ether of bisphenol-A epoxy system before and after curing was analyzed to develop nanostructured epoxy thermosets. For ED higher than 69 mol %, BCPs were miscible, while those with lower ED presented macrophase separation. Highly epoxidized BCPs obtained by the DMDO methodology were successfully used to obtain ordered nanodomains inside the epoxy matrix, as determined by atomic force microscopy. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: [4505][4506][4507][4508][4509][4510][4511][4512][4513] 2011

Preparation and characterization of polarity-modulated SIS-based hot-melt pressure-sensitive adhesives

“…[22,[28][29][30] To synthesize templates for nanostructured thermosets, metal catalyzed/hydrogen peroxide, dimethyldioxirane, and meta-chloroperbenzoic acid have been utilized to epoxidize SIS or SBS copolymers with high epoxidation degrees (>60 mol%). [22,23,29,31,32] But, they are seldom used to polarize the HMPSAs because most of them can produce a significant amount of side reactions, such as ring opening and cross-linking. Furthermore, high epoxidation degrees may shift glass transition temperature of diene phase outside the HMPSAs window.…”

“…These methods have been used to introduce polar functional groups in the styrene or diene blocks of the styrenic block copolymers. [12,[21][22][23][24][25][26][27] Among these methods, the epoxidation procedures are utilized to incorporate epoxide groups into the diene blocks of the copolymers, in which some oxidants, such as metal catalyzed/hydrogen peroxide, dimethyldioxirane, meta-chloroperbenzoic acid, and in situ per-formic acid, have been adopted. [22,[28][29][30] To synthesize templates for nanostructured thermosets, metal catalyzed/hydrogen peroxide, dimethyldioxirane, and meta-chloroperbenzoic acid have been utilized to epoxidize SIS or SBS copolymers with high epoxidation degrees (>60 mol%).…”

Polar polystyrene‐isoprene‐styrene copolymers with long polybutadiene branches

“…As an important family of materials in the category of thermoplastic elastomers, polystyrene‐isoprene‐styrene (SIS) and polystyrene‐butadiene‐styrene (SBS) tri‐block copolymers are widely used in rubber soles in footwear, asphalt modification, elastic film, soft molded parts, viscosity modification for oils and gels, adhesives, nanostructured thermosetting matrices, nanoparticle filled composites, competitive double‐networked copolymers, thermoplastic compounds, actuation applications as a kind of electric field‐activated electroactive polymers, biomedicines, and membranes due to their microphase‐separated structures . The styrene phase provides excellent strength as physical crosslinks and the soft conjugated diene phase exhibits the behaviors of vulcanized rubber at their service temperature by covalently bonding the thermodynamically incompatible styrene phase .…”

“…To increase their compatibility with polar materials, various strategies are used to introduce polar functional groups in both the styrene and diene blocks, including graft, sulfonation, plasma, and epoxidation treatments . Among these methods, the epoxidation procedures are utilized to incorporate epoxide groups into the diene blocks of the copolymers, in which some oxidants, such as metal catalyzed/hydrogen peroxide, dimethyldioxirane, meta‐chloroperbenzoic acid and in situ peracetic acid, have been adopted .…”

“…Among these methods, the epoxidation procedures are utilized to incorporate epoxide groups into the diene blocks of the copolymers, in which some oxidants, such as metal catalyzed/hydrogen peroxide, dimethyldioxirane, meta‐chloroperbenzoic acid and in situ peracetic acid, have been adopted . To synthesize templates for nanostructured thermosets, metal catalyzed/hydrogen peroxide, dimethyldioxirane and meta‐chloroperbenzoic acid have been utilized to epoxidize SIS or SBS copolymers with high epoxidation degrees (>60 mol %) . Comparatively, the in situ peracetic acid is preferred to epoxidize polybutadienes, styrene–butadiene rubber, SBS, natural rubber and SIS due to its environment‐friendly feature, stability, and easy manipulation …”