Morphology and Deformation Mechanisms and Tensile Properties of Tetrafunctional Multigraft Copolymers

Abstract

Morphology and deformation mechanisms and tensile properties of tetrafunctional multigraft (MG) polystrene-g-polyisoprene (PS-g-PI) copolymers were investigated dependent on PS volume fraction and number of branch points. The combination of various methods such as TEM, real time synchrotron SAXS, rheo-optical FTIR, and tensile tests provides comprehensive information at different dimension levels. TEM and SAXS studies revealed that the number of branch points has no obvious influence on the microphase-separated morphology of tetrafunction MG copolymers with 16 wt % PS. But for tetrafunctional MG copolymers with 25 wt % PS, the size and integrity of PS microdomains decrease with increasing number of branch point. The deformation mechanisms of MG copolymers are highly related to the morphology. Dependent on the microphase-separated morphology and integrity of the PS phase, the straininduced orientation of the PS phase is at different size scales. Polarized FT-IR spectra analysis reveals that, for all investigated MG copolymers, the PI phase shows strain-induced orientation along SD at molecular scale. The proportion of the PI block effectively bridging PS domains controls the tensile properties of the MG copolymers at high strain, while the stress-strain behavior in the low-mediate strain region is controlled by the continuity of PS microdomains. The special molecular architecture, which leads to the higher effective functionality of PS domains and the higher possibility for an individual PI backbone being tethered with a large number of PS domains, is proposed to be the origin of the superelasticity for MG copolymers.

Sustainable thermoplastic elastomers derived from renewable cellulose, rosin and fatty acids

“…Again, the optimal DAEMA content seems to be in the 25-45% range, yielding copolymers with T g values 10-30 C below ambient temperature. The three samples with intermediate DAEMA content (30,35, and 40%) all showed steep stress increases at low strain, ductile yielding, and elastoplastic deformation to large failure strains (>500%). As DAEMA content increases, the failure strain decreases, but the failure tensile stress increases.…”

“…These gra copolymers consist of either so backbone and hard side chains, or rigid backbone and rubbery side chains, which can be prepared by various graing chemistry strategies. 25,[33][34][35][36] For instance, polyisoprene-g-polystyrene (PI-g-PS) has been synthesized via anionic polymerization as gra copolymer-based TPE. 34,35 The Kramer and Bazan groups developed a gra copolymer by graing so n-butyl acrylate from rigid polyethylene copolymer backbone through ATRP.…”

“…25,[33][34][35][36] For instance, polyisoprene-g-polystyrene (PI-g-PS) has been synthesized via anionic polymerization as gra copolymer-based TPE. 34,35 The Kramer and Bazan groups developed a gra copolymer by graing so n-butyl acrylate from rigid polyethylene copolymer backbone through ATRP. 37 Recently, we used activator-regenerated electron transfer (ARGET) ATRP 38 to prepare a series of cellulose-based gra copolymers, cellulose-g-poly(n-butyl acrylate-co-methyl methacrylate), as new candidate TPE materials.…”

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“…Structure-property relationship of these graft copolymers was elucidated by characterizing morphology [76,77] and mechanical properties [78][79][80] of grafted polymers with different compositions (14-23 vol% of PS) and architectures (trifunctional, tetrafunctional, and hexafunctional junction points). From their research, multigraft polymers with tetrafunctional junction points showed 1550% strain at break which is 500% higher than that for the commercial product Kraton 1102.…”

A controlled synthesis method of polystyrene-b-polyisoprene-b-poly(methyl methacrylate) copolymer via anionic polymerization with trace amounts of THF having potential of a commercial scale

“…13 However, to date, there is almost no one polar monomer, which could be used as the monomer in the anionic polymerization in industrial scale, also including the commonly used methyl methacrylate (MMA). Due to too more side reactions are likely to occur during the anionic polymerization of MMA.…”