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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.

Polyamide 11 (PA11) is a semicrystalline polymer with excellent mechanical property. However, the use of PA11 with high crystallinity as an engineering plastic is limited because of its low impact resistance. In this work, a series of sustainable poly(PA11-co-DA) copolymers (PAx-p-DAy) were synthesized via polycondensation from vegetable oil-based dimer acid (DA) and diamine terminated polyamide 11 (ATPA11-x). The molecular structure of PAx-p-DAy was characterized by 1 H NMR, 13 C NMR, FT-IR, XRD, and viscometry. The mechanical properties of the periodic copolymers depended on the bulky DA content and the chain length of ATPA11-x. As the content of bulky DA increased and the chain length of ATPA11-x decreased, the degree of crystallinity of the PAx-p-DAy copolymers decreased, but the tensile strength, elongation, and tensile toughness increased. In addition, the low-temperature and room-temperature impact toughness of the copolymer was also remarkably improved. These thermoplastic polyamides have the potential to be widely applied.

A series of thermoplastic elastomer (TPE) systems with an ABA-type triblock structure, derived from renewable resources, were prepared using an eco-friendly approach, subsequently developed to demonstrate industrial applications ranging from pressure-sensitive adhesive (PSA) to elastomer, and structurally broken by degradation process. First, α,ω-dihydroxy poly(δ-hexalactone)s (PHLs) as a rubbery block (B), which could be derived from vegetable-oil, were precisely synthesized with target M n values of 30 and 60 kg mol −1 for desirable viscoelastic performance, using metal-free ring-opening polymerization (ROP) with an organic base catalyst. The end-hydroxyl groups of the PHLs were completely esterified with a chain-transfer agent (CTA). Second, the resulting macro-CTAs were initiated via reversible addition−fragmentation chain-transfer (RAFT) polymerization of lignin-based guaiacol methacrylate (GM) for a hard side block (A). Finally, poly(guaiacol methacrylate) (PGM)−PHL−PGM triblock copolymers were prepared with f PGM of 0.21 and 0.30. The clearly defined molecular structures resulted in controlled block sizes and a microphase-separated structure. The PGM−PHL−PGM(5−30−5) prepared without a functional additive showed low tack PSA performance based on the viscoelastic window, including a peel adhesion of 0.48 N cm −1 and a tack force of 0.06 N, comparable to those of commercial removable/repositionable tapes. PGM−PHL−PGM(15−60−15) exhibited features of a soft superelastomer, with an elongation at break (ε b ) of >1500%, a tensile modulus of 2.07 MPa, and an ultimate strength at break of 3.09 MPa. Degradation of the PGM−PHL−PGM triblocks could be attributed to the hydrolysis of the poly(ester) PHL blocks up to 91−94% and the catalyst-free depolymerization of the RAFT-synthesized PGM blocks up to 56−64%.

A series of poly[amide11-alt-poly(dimer acid-alt-1,5-diamino-2-methyl)] multiblock copolymers [PA11 Hx -alt-(DA-MP) Sy ] with high renewable content (up to 95%) was synthesized via bulk polycondensation of a plant oil-based diacid-terminated PA11 hard block (PA11 Hx ) and a diamine-terminated PA soft block [(DA-MP) Sy ] (w soft block = 0.31−0.90). The tunable and superior mechanical properties (E = 4−233 MPa, σ yield = 20−33 MPa, σ b = 744−2233%, and γ = 222−359 MJ m −3 ) of the PA11 Hxalt-(DA-MP) Sy depended on the chain lengths of both the crystalline hard block and the amorphous soft block.The performance of the pressure-sensitive adhesive (PSA) system that includes the multiblock was assessed, revealing a peel strength of 3.52 N cm −1 , a probe tack of 0.45 N, and shear strength of >50 000 min, which are competitive to commercial PSA tape. The molecular structure of the PA11 Hx -alt-(DA-MP) Sy was analyzed by 1 H NMR, 13 C NMR, FTIR, TBN, and GPC. High-purity monomers were recovered through acid-catalyzed hydrolysis of a sustainable multiblock copolymer with >99% conversion rate (calculated based on crude 1 H-NMR analysis). These novel multiblocks and the chemical recycling method could provide a potential for sustainability.

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