Cellulose nanocrystals were preparedviashort-time pretreatment by electron-beam irradiation in the solid state and disintegration using high pressure homogenization.

Highly compatible PLA plasticizers were prepared using lactide, which demonstrated “double green” based on renewability and biodegradation, and “dual performances” including flexible and elastomeric behaviors.

Efficient mixing and energy delivery by ball-milling promoted the lactide polymer growth from macroinitiators without the use of a solvent.

Sustainable, mechanically reinforced, and hydrolytically degradable thermoset elastomers were synthesized by one-pot, three-step synthesis & crosslinking.

A sustainable nanofabrication approach is developed for isolating hybrid nanocelluloses (Hy-NCs) comprised of both long flexible fibers (CNFs) and needle-like crystals (CNCs) from a hardwood wet pulp (WP) using electron-beam irradiation (EBI). The method was applied to prepare spray-dried powders that could be transparently redispersed. As a result, the disassociated wet pulps had increased carboxylate contents of 0.04−0.12 mmol g −1 compared to the initial wet pulps and the corresponding dried pulps. The irradiated pulp was subsequently disintegrated by alkaline high-pressure homogenization to form stable Hy-NC dispersions which retained background transparency due to the considerable negative surface charges of −34 to −38 mV. The resulting NC-WP-E0500 and NC-WP-E1000 dispersions were prepared in two mixtures with CNF/CNC ratios of 68/32 and 33/67, based on a 700 nm length to determine CNF and CNC, with the average lengths of 927 ± 512 and 653 ± 382 nm, respectively. NC-WP-E1000 was neutralized with CO 2 , spray-dried to prepare dehydrated products, and was clearly redispersible. We also studied oilin-water (O/W) Pickering emulsions formed by the Hy-NC particles, observed by merged confocal and SEM images. NC-WP-E1000 promoted monodispersed oil droplets of around 2.6 μm where bimodal distribution converged, which remained stable even when creaming force was applied for highly concentrated (dense) emulsion applications. This could be attributed both to the degree of viscoelastic thickening and depletion stabilization by the still repulsive and nonabsorptive CNFs in the continuous phase and the absorption caused by CNC layer at the O/W interfaces in the emulsions.

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.

A mechanically adjustable reinforced thermoplastic superelastomer system, with tunable gas-permeability, was developed. The superelastomer is based on a graft copolymer structure, using commercial butyl rubbers (or poly­(isobutylene-co-isoprene), P­(IB-co-I)) and l- or d,l-lactide (LLA or LA) derived from renewable feedstocks, by a “grafting from” controlled polymerization. First, hydroxyl-functionalized PIB (PIB-g-(OH)) macroinitiators were prepared through epoxidation using an economical alternative to m-chloroperoxybenzoic acid and ring-opening reaction. Second, PIB-based graft copolymers with end-hydroxylated poly­(lactide) as hard side-chains, PIB-g-(P­(L)­LA–OH)­s, were synthesized to target f P(L)LA of 0.18–0.45, to achieve mechanical reinforcement and an additional gas barrier. They were subsequently acetylated with an acetic anhydride to produce PIB-g-(P­(L)­LA–Ac)­s with improved thermal stability. The well-defined molecular structures indicated controlled P­(L)­LA lengths, and the resulting superelastomers demonstrated improved thermal stability with increased T d,5%; microphase-separated structures having spherical and/or elongated features; thermoplastic behaviors proved by T ODT, which were much lower than the resulting T d,5%; and superior and adjustable mechanical characterizations, proving to control elastomeric-to-ductile properties. An oxygen permeability value as low as 27 mL mm m–2 day–1 atm–1 was achieved by increasing f P(L)LA to 0.45, comparable to polyethylene terephthalate. The partially biodegradable and processable gas barrier films based on these PIB-g-PLLA thermoplastic superelastomers have great potential for the flexible packaging of food and medical products.

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%.