The
synthesis and characterization of poly(phenylene polysulfide)
networks (PSNs) with controlled average sulfur ranks, from elemental
sulfur (ES) and p-diiodobenzene (DIB), are investigated.
The PSN films, prepared via simple hot pressing, are found to possess
large extensibility up to around 300% and complete recovery of shape
and mechanical properties after deformation, which are attributed
to the loosely cross-linked network structures mainly consisting of
linear poly(phenylene polysulfide) chains. The covalent polysulfide
linkages in the PSNs also exhibit dynamic behaviors under ultraviolet
(UV) or thermal treatment, thus, enabling self-healing and reprocessing
of the films when scratched and broken, respectively. Combined with
the unique mechanical properties of the PSNs, their high refractive
index and excellent infrared (IR) transparency contribute to the preparation
of stretchable, healable, and reprocessable IR transmitting materials
for potential deformable and stretchable optical applications.
Thermadapt shape memory polymers (SMPs), utilizing a variety of dynamic covalent bond exchange mechanisms, have been extensively studied in recent years but it is still challenging to address several constraints in terms of limited accuracy and complexity for constructing 3D shape memory structures. Here, an effective and facile preparation of thermadapt SMPs based on elemental sulfur‐derived poly(phenylene polysulfide) networks (PSNs) is presented. These SMPs possess intrinsic near‐infrared (NIR)‐induced photothermal conversion properties for spatiotemporal control of their plasticity and elasticity. The NIR‐controllable plasticity and elasticity of the PSNs enable versatile shape manipulation of 3D multi‐shape memory structures, including building block assembly, reconfiguration, shape fixing/recovery, and repair.
Front Cover: In article 2000013, Dong‐Gyun Kim, Ho Gyu Yoon, Yong Seok Kim, and co‐workers report an effective and facile preparation of thermadapt shape‐memory polymers based on elemental‐sulfur‐derived poly(phenylene polysulfide) networks (PSNs), which possess intrinsic near infrared (NIR)‐induced photothermal conversion properties for enabling spatiotemporal control of their plasticity and elasticity. The NIR‐controllable plasticity and elasticity of the PSNs eventually lead to the realization of versatile shape manipulation of 3D multi‐shape memory structures, including building‐block assembly, reconfiguration, shape fixing/recovery, and repair.
In this work, we evaluated catalytic activity of LiOH, Cu(acac) 2 and n-butyltin hydroxide oxide hydrate in the early stage of the melt transesterification of isosorbide and bisphenol A as diol monomers and diphenylcarbonate for the melt polymerizaiton of polycarbonate. Cu(acac) 2 proved to be the most active catalyst for homopolymerization process, while the catalytic activity of LiOH was higher than the others in case of melt copolymerization depending on the catalytic mechanism and chemical structure of catalyst. We suggested that evaluation of catalytic activity can be used for selection of catalyst system in bio-based copolymerization of polycarbonate.
Polyimide (PI) containing carboxyl functional group was prepared and reacted with diaminosiloxane during high temperature film casting. The morphology of resulting film was observed by using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX), which revealed that globular 100 nm-sized PI domains and continuous polysiloxane phase were formed. X-ray photoelectron spectroscopy (XPS) study indicated that air-film interface mainly consisted of polysiloxane blocks. Poly(imidesiloxane) thin layer was thermostable until 400 o C and its pressure-sensitive adhesive property was retained up to 300 o C. The comparative experiments revealed that grafting between carboxyl groups of polyimide and aminosiloxane was crucial for formation of microdomain structure and pressure-sensitive adhesive property.Keywords: polyimide, poly(imidesiloxane), pressure-sensitive adhesion, thermostable, grafting copolymer.
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