Toughening of in situ polymerized cyclic butylene terephthalate by chain extension with a bifunctional epoxy resin

Concept of a six-fold multiplex planar bioassay to distinguish endocrine agonist, antagonist, cytotoxic and false-positive responses

To analyze a complex sample for endocrine activity, different tests must be performed to clarify androgen/estrogen agonism, antagonism, cytotoxicity, anti-cytotoxicity, and corresponding false-positive reactions. This means a large amount of work. Therefore, a six-fold planar multiplex bioassay concept was developed to evaluate up to the mentioned six endpoints or mechanisms simultaneously in the same sample analysis. Separation of active constituents from interfering matrix via high-performance thin-layer chromatography and effect differentiation via four vertical stripes (of agonists and end-products of the respective enzyme-substrate reaction) applied along each separated sample track were key to success. First, duplex endocrine bioassay versions were established. For the androgen/anti-androgen bioassay applied via piezoelectric spraying, the mean limit of biological detection of bisphenol A was 14 ng/band and its mean half maximal inhibitory concentration IC50 was 116 ng/band. Applied to trace analysis of six migrate samples from food packaging materials, 19 compound zones with agonistic or antagonistic estrogen/androgen activities were detected, with up to seven active compound zones within one migrate. For the first time, the S9 metabolism of endocrine effective compounds was studied on the same surface and revealed partial deactivation. Coupled to high-resolution mass spectrometry, molecular formulas were tentatively assigned to compounds, known to be present in packaging materials or endocrine active or previously unknown. Finally, the detection of cytotoxicity/anti-cytotoxicity and false-positives was integrated into the duplex androgen/anti-androgen bioassay. The resulting six-fold multiplex planar bioassay was evaluated with positive control standards and successfully applied to one migrate sample. The streamlined stripe concept for multiplex planar bioassays made it possible to assign different mechanisms to individual active compounds in a complex sample. The concept is generic and can be transferred to other assays.

Compatible Ag+ Complex-Assisted Ultrafine Copper Pattern Deposition on Poly(ethylene terephtalate) Film with Micro Inkjet Printing

Firm immobilization of catalysts on the predesigned position over substrates is an essential process for producing flexible circuits by the electroless deposition (ELD) process. In this work, a compatible Ag⁺ complex was developed and directly printed on the poly(ethylene terephtalate) (PET) film through a micro inkjet printing instrument to trigger the deposition of ultrafine copper patterns with approximately 20 μm in width. Morphological and elementary characterization verified that the nanosized silver catalyst was uniformly distributed in the bridge layer, which could enhance the adhesion between the PET film and deposited copper patterns. Moreover, after 30 min of ELD, the copper patterns exhibited a low resistivity of 2.68 × 10^-6 Ω·cm and maintained considerable conductivity even after 2000 times of cyclical bending. These interesting conductive and mechanical features demonstrate the tremendous potential of this Ag⁺ complex-assisted copper deposition in the interconnection of high-density integrated flexible electronics.

Chain Extension and Synergistic Flame-Retardant Effect of Aromatic Schiff Base Diepoxide on Polyamide 6/Aluminum Diethylphosphinate Composites

A way to suppress the deterioration in mechanical properties of polyamide 6 (PA6) is required, especially with high loading of flame retardants in the matrix. In this study, a novel aromatic Schiff base diepoxide (DES) was synthesized. It exhibited an efficient chain extension effect on PA6 and a synergistic flame-retardant effect with aluminum diethylphosphinate (AlPi) for PA6. The PA6 composite with 16 wt.% AlPi only passed UL-94 V-0 rating at 1.6 mm thickness, while the combination of 1.5 wt.% DES with 13 wt.% AlPi induced PA6 to achieve a UL-94 V-0 rating at 0.8 mm thickness. The tensile, flexural, and Izod notched impact strengths were increased by 16.2%, 16.5%, and 24.9%, respectively, compared with those of V-0 flame-retarded PA6 composites with 16 wt.% AlPi. The flame-retarded mechanism of PA6/AlPi/DES was investigated by cone calorimetry and infrared characterization of the char residues and pyrolysis products. These results showed that DES had a synergistic effect with AlPi in condensed-phase flame retardation by promoting the production of aluminum phosphorus oxides and polyphosphates in the char residues.

Reduction-sensitive amphiphilic copolymers made via multi-component Passerini reaction for drug delivery

One-step synthesis of amphiphilic polymers containing disulfide bond within the hydrophobic backbone was demonstrated via multi-component Passerini reaction. The obtained polymer was self-assembled into micelles in aqueous solution. Curcumin (CUR), an effective and safe anticancer agent, which was limited by its water insolubility and poor bioavailability, was loaded into the micelles as a model drug. The nanoscale polymeric micelles were confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Faster intracellular CUR release was observed by confocal laser scanning microscopy (CLSM) in the HeLa cells pretreated with GSH than in the unpretreated ones. Micelles also loaded with NH2-BODIPY which was almost non-fluorescent and gave strong enhanced fluorescence under acid conditions. The phenomenon of the stronger enhanced fluorescence in the pretreated HeLa cells showed further that the obtained polymer was reduction-sensitive. In vitro MTT assays showed that the micelles were biocompatible and CUR-loaded micelles had higher cellular proliferation inhibition in contrast to free CUR toward HeLa cells. These results highlight the potential of using multi-component Passerini reaction to make functional copolymers as smart nanocarriers for drug delivery.

Application of bis(glycidyloxy)phenylphosphine oxide as a chain extender for polyamide-6

Figure melt torque of PA6 mixed with different contents of chain extender BGPPO. The addition of small molecule diepoxide (BGPPO) greatly enhanced the melt torque, rheological and mechanical properties of polyamide-6 through chain extension reaction.

Performance improvement of flame-retarded poly(butylene terephthalate)/aluminum diethylphosphinate composites by epoxy-functional polysiloxane

An epoxy-functional polysiloxane (EPM) was employed for improving the performance of flame-retarded poly(butylene terephthalate)/aluminum diethylphosphinate (PBT/AlPi) composites. The effect was investigated by UL-94 test, limiting oxygen index, mechanical test, torque rheometer measurement, differential scanning calorimetry, dynamic mechanical analysis, and heat distortion temperature. An obvious increase in torque evolution of the PBT/AlPi composite during processing was associated with chain-extending, branching, and cross-linking reaction by the combination of EPM. The addition of 0.6 wt% EPM remarkably enhanced not only the mechanical properties but also the flame retardancy and heat resistance of the PBT/AlPi composite. A high-performance PBT/AlPi composite was developed by virtue of EPM.