Modification of polylactide by poly(ionic liquid)-b-polylactide copolymer and bio-based ionomers: Excellent toughness, transparency and antibacterial property.

Polylactide (PLA) is one of the most attractive bioplastics as it can be produced from nontoxic renewable feedstock. However, its inherently poor toughness greatly limits its large-scale application. Cost-effectively toughening PLA without sacrificing its transparency remains a big challenge. We herein prepared an imidazolium-based poly(ionic liquid)-b-PLA copolymer (ILA) and ionomers as toughening agent for PLA through an integrative approach including continuous-monomer-feeding copolymerization, quaternization reaction, ion exchange and inter-ionomers blending. By blending PLA with the ILA and ionomers, we successfully obtained PLA materials with combined features including high toughness, good transparency and antibacterial properties. The effects of regulated ionomer composition and ILA compatibilizer on phase morphology, mechanical properties and transparency of the blends were systematically studied. The optimum formulation (PLA/E12/ILA 60/40/5) shows an impressive transmittance of 89-93 %, high impact strength of 45 kJ/m2 and elongation at break at 170 %, which are about 17 and 24 times that of pure PLA, respectively. More interestingly, the presence of imidazolium cation and anion groups endows the blends with attractive antibacterial properties. Ion exchange between ILA copolymer and the imidazolium-containing ionomeric system leads to a synergistic effect of compatibilization and efficient toughening, providing a new strategy for develop high performance PLA materials.

Ultra-Tough Polylactide/Bromobutyl Rubber-Based Ionomer Blends via Reactive Blending Strategy.

A series of ultra-toughened sustainable blends were prepared from poly(lactic acid) (PLA) and bromobutyl rubber-based ionomers (i-BIIRs) via reactive blending, in which dicumyl peroxide (DCP) and Joncryl®ADR-4440 (ADR) were used as reactive blending additives. The miscibility, phase morphology and mechanical property of the PLA/i-BIIRs blends were thoroughly investigated through DMA, SEM, tensile and impact tests. The influence of different ionic groups and the effects of DCP and ADR on the compatibility between the phases, phase structure and mechanical properties were analyzed. The introduction of the imidazolium-based ionic groups and the reactive agents enable the i-BIIRs play multiple roles as effective compatibilizers and toughening agents, leading to improved interfacial compatibility and high toughness of the blends. The mechanical properties test showed that the PLA/i-BIIRs blends exhibit excellent toughness: impact strength and the elongation at break of AR-OH(30)+AD reached 95 kJ/m2 and 286%, respectively. The impact fracture surface showed the large-scale plastic deformation of the PLA matrix in the blends, resulting in greatly absorbing the impact energy. The results proved that simultaneously applying reactive blend and multiple intermolecular interactions methods is an effective toughening strategy for toughening modification of the PLA blends.

Post-chemical grafting poly(methyl methacrylate) to commercially renewable elastomer as effective modifiers for polylactide blends.

A novel poly(epichlorohydrin-co-ethylene oxide)-g-poly(methyl methacrylate) copolymer (ECO-g-PMMA) was successfully synthesized from a commercially renewable elastomer via the ATRP method. The graft copolymer was investigated as a toughening agent and compatibilizer for polylactide (PLA) and PLA/ECO blends, respectively. Binary blending PLA with the copolymers (5-15 wt%) significantly improved the strain at break of PLA above 200% without a great strength loss. More importantly, the ternary PLA/ECO/ECO-g-PMMA copolymer blends exhibited a remarkably high impact strength of 96.9 kJ/m2 with non-broken behaviors. An interesting phase structure transformation from a typical sea-island structure to a unique quasi-continuous network structure was observed with varying the content of ECO-g-PMMA from 0 to 15 wt% in the ternary blends. The native toughening mechanism analysis indicated the synergistic toughening effect of the good interfacial adhesion and unique quasi-continuous morphology endowed the ternary blends with excellent mechanical performance.

Pituitary 18F-FDG uptake correlates with serum TSH levels in thyroid cancer patients on 18F-FDG PET/CT.

OBJECTIVE: The objective of this study was to evaluate the relationship between fluorine-18-fluorodeoxyglucose (F-FDG) uptake in the pituitary gland and serum thyroid-stimulating hormone (TSH) levels in differentiated thyroid cancer (DTC) patients on F-FDG PET/computed tomography (CT). PATIENTS AND METHODS: A total of 215 DTC patients and 215 age-paired and sex-paired healthy screening participants were included. DTC patients were divided into hypothyroid, euthyroid and subclinical hyperthyroid patients according to their serum TSH levels. The relationship between F-FDG uptake in the pituitary gland and serum TSH levels was evaluated the in DTC patients, and the pituitary F-FDG metabolism was compared in different thyroid status. RESULTS: The standardized uptake value of pituitary (SUVp) in all 430 patients was directly correlated with serum TSH levels (r=0.479 and 0.432, all P<0.05). The SUVp in DTC patients was higher than that in 215 healthy participants (z=-10.4, P<0.05). No significant difference of SUVp was observed between euthyroid patients and healthy participants (P=0.145). CONCLUSION: Our study established the positive correlation between pituitary F-FDG uptake and serum TSH. TSH values should be measured in patients with incidental pituitary uptake during F-FDG PET/CT. L-T4 replacement for DTC patients may well have the same feedback on the thyroid-pituitary axis as the physiologic thyroid status. The diffuse F-FDG uptake with normal CT or MRI appearance of the pituitary in patients with DTC indicates physiologic uptake.

Whole-body MRI versus 18F-FDG PET/CT for pretherapeutic assessment and staging of lymphoma: a meta-analysis.

PURPOSE: 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is the reference standard in staging of 18F-FDG-avid lymphomas; however, there is no recommended functional imaging modality for indolent lymphomas. Therefore, we aimed to compare the performance of whole-body magnetic resonance imaging (WB-MRI) with that of 18F-FDG PET/CT for lesion detection and initial staging in patients with aggressive or indolent lymphoma. MATERIALS AND METHODS: We searched the MEDLINE, EMBASE, and CENTRAL databases for studies that compared WB-MRI with 18F-FDG PET/CT for lymphoma staging or lesion detection. The methodological quality of the studies was assessed using version 2 of the "Quality Assessment of Diagnostic Accuracy Studies" tool. The pooled staging accuracy (µ) of WB-MRI and 18F-FDG PET/CT for initial staging and for assessing possible heterogeneity (χ2) across studies were calculated using commercially available software. RESULTS: Eight studies comprising 338 patients were included. In terms of staging, the meta-analytic staging accuracies of WB-MRI and 18F-FDG PET/CT for Hodgkin lymphoma and aggressive non-Hodgkin lymphoma (NHL) were 98% (95% CI, 94%-100%) and 98% (95% CI, 94%-100%), respectively. The pooled staging accuracy of 18F-FDG PET/CT dropped to 87% (95% CI, 72%-97%) for staging in patients with indolent lymphoma, whereas that of WB-MRI remained 96% (95% CI, 91%-100%). Subgroup analysis indicated an even lower staging accuracy of 18F-FDG PET/CT for staging of less FDG-avid indolent NHLs (60%; 95% CI, 23%-92%), in contrast to the superior performance of WB-MRI (98%; 95% CI, 88%-100%). CONCLUSION: WB-MRI is a promising radiation-free imaging technique that may serve as a viable alternative to 18F-FDG PET/CT for staging of 18FDG-avid lymphomas, where 18F-FDG PET/CT remains the standard of care. Additionally, WB-MRI seems a less histology-dependent functional imaging test than 18F-FDG PET/CT and may be the imaging test of choice for staging of indolent NHLs with low 18F-FDG avidity.