DOI: 10.25349/d99p6h
title: Data from: Improved elastic recovery from ABC triblock terpolymers

description: The promise of ABC triblock terpolymers for improving the mechanical
 properties of thermoplastic elastomers is demonstrated by comparison with
 symmetric ABA/CBC analogs having similar molecular weights and volume
 fraction of B and A/C domains. It is shown that the ABC architecture
 enhances elasticity (up to 98% recovery over 10 cycles) in part through
 essentially full chain bridging between discrete hard domains leading to
 minimization of mechanically unproductive loops. In addition, the unique
 phase space of ABC triblocks also enables the fraction of hard-block
 domains to be higher (fhard ≈ 0.4) while maintaining elasticity, which is
 traditionally only possible with non-linear architectures or highly
 asymmetric ABA triblock copolymers. These advantages of ABC triblock
 terpolymers provide a tunable platform to create materials with practical
 applications while improving our fundamental understanding of chain
 conformation and structure–property relationships in block copolymers.
description: <sup>1</sup>H nuclear magnetic resonance
 spectroscopy Solution state <sup>1</sup>H
 nuclear magnetic resonance (NMR) spectra were recorded on a Varian VNMRS
 600 MHz spectrometer. Chemical shifts (<em>δ</em>) are
 reported in ppm relative to residual protio-solvent in
 CDCl<sub>3</sub> (7.26 ppm). Size-exclusion
 chromatography instrumentation Size-exclusion
 chromatography (SEC) was performed on a Waters instrument using a
 differential refractive index detector and two Tosoh columns (TSKgel
 SuperHZM-N, 3 μm polymer, 150 × 4.6 mm) with chloroform containing 0.25%
 TEA at 35 °C as the mobile phase. Molar masses and molar mass dispersity
 (<em>Đ</em>) were determined against narrow PS standards
 (Agilent).  Mechanical analysis
 Frequency sweeps and isochronal temperature sweeps were obtained
 on a TA Instruments ARES G2 in oscillatory shear mode with a 25 mm
 parallel-plate geometry and a nitrogen-purged forced–convection oven. For
 all experiments, oscillatory shear was applied within the linear
 viscoelastic regime as verified from isochronal strain sweeps at a fixed
 temperature. Isochronal (ω = 1 rad/s) temperature ramps employing small
 strain amplitudes, typically <em>γ</em> ≤ 1%, and low heating
 rates (2 °C/min) were used to measure the order–disorder transition
 temperature (<em>T</em><sub>ODT</sub>).
 Differential Scanning Calorimetry (DSC) was performed using a TA
 Instruments DSC Q2000 at a heating/cooling rate of 10 °C/min using 3–5 mg
 of sample in a sealed aluminum pan. Samples for mechanical testing were
 heat pressed using a Carver press (Wabash, IN) into a 0.5 mm thick steel
 rectangular mold with 5000 lbf at 180 °C for 10 min and then rapidly
 cooled to room temperature to suppress crystalline break out. All samples
 were aged at room temperature for 16 – 18 h prior to uniaxial tensile to
 ensure adequate crystallization of the
 <em>poly</em>(L-lactide) and consistency throughout samples.
 Temperature–dependent modulus data were obtained on a TA Instruments DMA
 850 with a film clamp geometry and a nitrogen–purged oven using a strain
 of 0.05% at a frequency of 1 Hz and a temperature ramp rate of 5 °C/min.
 Samples were approximately 3 mm by 8 mm by 1.5 mm. For uniaxial extension
 tensile tests, a dog bone cutting die was used to punch out samples of the
 correct geometry (gauge depth = 0.5 mm, gauge width = 1.5 mm, gauge length
 = 10 mm, transition zone radius = 2.5 mm). Tests were performed using a
 custom-built setup with a vertical TwinRail positioning table (Lintech,
 CA) and a 10 N load cell (LSB2000 Miniature S-Beam, FUTEK, CA). A
 deformation rate of 10 mm min<sup>−1</sup> was used for all
 tests (strain rate = 1 min<sup>−1</sup>). Cyclic testing of
 was performed on a TA.XTplusC texture analyzer equipped with A/MTG tensile
 grips. Ten cycles were performed for each experiment with a deformation
 rate of 10 mm min<sup>−1</sup>, an unloading rate of 10 mm
 min<sup>−1</sup>, and force tracking at a rate of 10 mm
 min<sup>−1</sup> with a 10 min dwell after each cycle to
 ensure complete relaxation of the thermoplastic elastomer. All samples for
 mechanical testing were conducted on samples from the same molded sheets
 and thus exhibit the same thermal history. Small–angle
 X-ray Scattering (SAXS) SAXS experiments were conducted
 using a custom-built SAXS diffractometer at the Materials Research
 Laboratory (MRL) X-ray facility (University of California, Santa Barbara).
 For these experiments, 1.54 Ǻ Cu Kα X-rays were generated using a Genix 50
 W X-ray microsource (50 μm micro-focus) equipped with FOX2D collimating
 multilayer optics (Xenocs, France) and high efficiency scatterless single
 crystal/metal hybrid slits. A sample-to-detector distance of 1721.6 mm was
 employed. Triblock thermoplastic elastomer dog bone specimen was directly
 mounted to the sample holder for scattering. Dog bone samples were heat
 pressed using a Carver press into a 0.5 mm thick steel rectangular mold
 with 5000 lbf at 180 °C (180 °C &gt;
 <em>T</em><sub>m</sub> of PLLA &lt;
 <em>T</em><sub>ODT</sub> of the triblock) for 10
 min and then rapidly cooled to room temperature to suppress crystalline
 break out. Diblock copolymers were annealed at 180 °C for 16 h, slowly
 cooled to room temperature before and mounted on a metal washer with a
 Kapton tape backing.