Superior properties such as high strength, toughness and transparency of fully biobased poly(lactide) (PLA) were achieved simultaneously without any external modifiers. The improvement in properties is well explained by a structural/morphological study. Stereocomplex PLA (SC-PLA) was obtained by melt compounding asymmetric poly(Llactide)/poly(D-lactide) (PLLA/PDLA) blends at 200°C and confirmed by wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) analyses. The SC-PLA domains (d = 950−1200 nm) lead to a physical cross-link network in the PLLA matrix. Rheology and Molau experiment reveal two different microstructures as a function of SC-PLA content, i.e., the connection of SC-PLA domains varied from chain entanglement to direct molecular bridging when the SC-PLA content increased from 10% to 23%. The SC-PLA crystals and the cross-link network reinforced the PLLA matrix, resulting in increases in melt viscosity, modulus and yield strength. Surprisingly, the elongation at break of the PLLA/PDLA blends was increased concomitantly from 11% to 200% with the SC-PLA content up to 10%. The brittle-to-ductile transition is ascribed to the cross-link network and easy deformation/cavitation of the SC-PLA domains. In addition, the asymmetric PLLA/PDLA blends exhibit an average visible light transmittance as high as 70% and the blends showed excellent heat-resistance after a short annealing at 100°C.

We report solid iodine as precursor additive for achieving purified final organo-metallic perovskite crystals. By adding iodine, we found the reaction can be pushed towards pure iodine phase rather than the kinetically favoured chlorine phase. This approach can be applied in large crystalline perovskite solar cell and obtained improved average efficiency from 9.83 % to 15.58 %.

In this work we report the in situ preparation of fully biobased stereocomplex poly(lactide) (SC-PLA) nanocomposites grafted onto nanocrystalline cellulose (NCC). The stereocomplexation rate by compounding high-molar-mass poly(D-lactide) (PDLA) with comb-like NCC grafted poly(L-lactide) is rather high in comparison with mixtures of PDLA and PLLA. The rapid stereocomplexation was evidenced by a high stereocomplexation temperature (Tc-sc = 145 °C) and a high SC crystallinity (Xc-sc = 38%) upon fast cooling (50 °C/min) from the melt (250 °C for 2 min), which are higher than currently reported values. Moreover, the half-life crystallization time (175-190 °C) of the SC-PLA was shortened by 84-92% in comparison with the PDLA/PLLA blends. The high(er) stereocomplexation rate and the melt stability of the SC in the nanocomposites were ascribed to the nucleation effect of the chemically bonded NCC and the "memory effect" of molecular pairs in the stereocomplex melt because of the confined freedom of the grafted PLLA chains.

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Partially biobased thermoplastic vulcanizates (TPV) with novel morphology, superior properties and partial degradability were prepared by dynamic cross-link of saturated poly­(lactide) and ethylene-co-vinyl acetate (PLA/EVA) blends using 2,5-dimethyl-2,5-di­(tert-butylperoxy)­hexane (AD) as a free radical initiator. EVA showed higher reactivity with free radicals in comparison with PLA, leading to much higher gel content of the EVA phase (G f‑EVA) than that of the PLA phase (G f‑PLA). However, the G f‑PLA increased more steeply at AD content larger than 1 wt % where the reaction of EVA approached to a saturation point. The competing reaction changed the viscosity ratio of the two components (ηPLA/ηEVA) that resulted in a novel morphology evolution of the TPV, i.e., from sea–island-type morphology to phase inversion via a dual-continuous network-like transition and finally cocontinuity again with increasing the AD content. The cross-link and phase inversion considerably enhanced the melt viscosity (η*), elasticity (G′) and the solid-like behavior of the PLA/EVA-based TPV. Meanwhile, superior tensile strength (σt = 21 MPa), low tensile set (T s = 30%), moderate elongation (εb = 200%) and suitable stiffness (E′ = 350 MPa, 25 °C) were successfully achieved by tailoring the cross-link structure and phase morphology. In addition, the TPV are partially degradable in aqueous alkali. A degradation rate of approximately 5 wt % was achieved within 10 weeks at 25 °C and the degradation mechanism was investigated from both molecular and macroscopic levels. Therefore, this work provides a new type of partially biobased and degradable materials for substitution of traditional TPV.