Semicrystalline-Glassy Multiblock Copolymers via Mechanochemical Synthesis toward Tough Poly(lactide)

Abstract

A series of semicrystalline-glassy (poly(amide11)–poly(lactide)) n (PA11–PLA) n multiblock copolymers with >97% renewable carbon content were developed for tough PLA. The resulting copolymers exhibited superior mechanical performance, comparable to those of commercial PA11 and PLA. Amine-terminated PA11 with a M n,NMR of 12 kg mol–1 was prepared by bulk self-condensation and subsequently capped with only one LA molecule through mechanochemical ball milling, to produce HO–LA–PA11–LA–OH. After adding Sn(Oct)2, unreacted LA was propagated in one-pot by ring-opening polymerization to make PLA–PA11–PLA with a f PLA of 0.5–0.8. The hydroxyl-telechelic triblocks were also coupled with diisocyanate by ball milling to manufacture (PA11–PLA) n multiblocks. The well-defined molecular structures demonstrated controlled PA11 and PLA lengths. Thermal analysis determined the phase separation of PA11 and PLA based on T g,PLA (48–56 °C) and T m,PA11 (183–186 °C) and confirmed the two transitions of thermal degradation (T d). SAXS profiles of the multiblocks also verified their microphase-separated morphologies. The temperature dependence of χ for the PA11–PLA system, χPA11–PLA = (426.00 ± 4.81)/T – (0.90 ± 0.01), simply represented as 0.24 and 0.13 at 100 and 140 °C, was estimated using the T ODT values obtained from the DMA of three symmetric PLA–PA11–PLA triblocks with a f PLA of 0.5. The resulting semicrystalline-glassy multiblocks showed superior tensile characteristics, merging PLA-originated initial modulus and yield stress (E = 758–903 MPa and σyield = 57–63 MPa), and a PA11-derived toughening even with strain hardening (εb = 380–500%, σb = 40–51 MPa, and γ = 124–171 MJ m–3). These results show promising potential for polymeric materials with sustainability and strength-toughness balance.

Poly(amide11)-Incorporated Block Copolymers as Compatibilizers to Toughen a Poly(lactide)/Polyamide 11 Blend

“…The triblock and multiblock compatibilizers were synthesized in two steps and three steps, respectively, as in the semicrystalline PA11-glassy PLA multiblock copolymer synthesis in a previous study. 9 First, diamino-terminated PA11 (H 2 N−PA11−NH 2 , 5.2 and 12.2 kg mol −1 ) was prepared as a midblock by polycondensation with 11-aminoundecanoic acid (11-AUDA) and hexamethylene diamine (HMDA) at 3.4 and 1.5 mol %. Using 1 H NMR analyses, the formation of amide groups was confirmed by chemical shifts in H a at δ 3.61 and H c at 2.78 (Figure S2).…”

“…(as described in the Supporting Information, Calculation of the PLA−PA11 χ interaction parameter.) 9 Compared to the χ interaction parameters of other commercially available polymers, 34−39 this is a relatively high value, suggesting that PLA and PA11 are thermodynamically immiscible without a compatibilizer.…”

Vegetable Oil-Derived Polyamide Multiblock Copolymers toward Chemically Recyclable Pressure-Sensitive Adhesives

“…Therefore, strainhardening may occur and stress may be increased. 19,20 These mechanical properties were also compared to those of a previously reported PLA segment multiblock elastomer applied as a PSA (see Figure 7c and Table 2). PA11 H0.8 -alt-(DA-MP) S 8 .…”

“…However, when the polymer chain is uniaxially stretched, hydrogen bonds (acting as physical bridges) can be newly formed in the dense amide groups of PA11 H x while being oriented in the same direction. Therefore, strain-hardening may occur and stress may be increased. , These mechanical properties were also compared to those of a previously reported PLA segment multiblock elastomer applied as a PSA (see Figure c and Table ). PA11 H0.8 - alt -(DA-MP) S8.0 , PLLA–PDL–PLLA(20–100–20), and (LDP1.0BL) 2.7 are elastomers with a low Young’s modulus and can be applied to PSA, but the mechanical properties of PLA-based multiblocks are relatively weak (especially stress at break).…”

“…Most of the methods for modifying PA11 involve blending PA11 with other polymers. , The blending is simple in the processing, but it may cause compatibility problems due to the difference in polarity of each polymer being blended. − So, the block copolymer linked by chemical bonds can solve the problem of compatibility. There are few studies on PA11-based copolymers. − Kucera et al synthesized a multiblock copolymer with PA11 and polyisobutylene and Gardella et al synthesized a diblock copolymer with PA11 and poly­(lactic acid) . Arkema (Pebax, France) synthesized a PA11-based TPE linked by an ester linkage between two prepolymers, a carboxylic acid-terminated PA11 (hard segment) and a hydroxyl-terminated poly­(oxyalkylene) glycol (soft segment) .…”