Wei Wang,Guangchao Ye,Ying Zhang,Xiujie Bian,Peng Lin,Yuanyuan Dong,Pengfei Hao,Xiang Wang
The enhanced durability of biobased polylactide (PLA) is a critical prerequisite for it to be considered a viable alternative to petroleum-based polymers for long-term applications. Leveraging the performance improvements achieved through interface construction, PLA-biomass composites have garnered considerable interest and have been widely utilized as a completely degradable material. The hydrolytic behavior of PLA biocomposites in photo-hydrothermal environments was examined in this study in relation to the impact of biomass components and the specifically designed interface. We observed that biomass could act as an effective stabilizer in the composites, leading to a 25.6% reduction in the hydrolysis reaction rate constant. This stabilization occurs as biomass impedes the diffusion of water molecules and the extension of PLA molecular chains across various hydrothermal environments, thereby enhancing the hydrolytic resistance of PLA. The intriguing aspect is that this stabilizing effect of biomass could be moderated by an interface created through surface treatment, which facilitates enhanced transfer of active small molecules during the photolysis-hydrolysis process. Consequently, this approach presents a novel method for producing PLA biocomposites that offers excellent hydrolytic resistance, an adjustable degradation cycle, and expected potential applications in advanced packaging and agricultural domains. Highlights Biomass significantly enhances the hydrolysis resistance of polylactide (PLA) biocomposites. This stability boosts due to the obstructive and shielding effects of biomass. Effective interface could regulate the usable life of PLA biocomposites. The role that biomass/ interfaces play also applies to PLA photodegradation. Photo-hydrolysis mechanism is not affected by biomass or designed interface.
Abstract Fossils are nonrenewable natural heritages formed by Mother Nature. After being excavated or exposed, fossils can be destroyed by weathering and water erosion. However, until now, there is very limited research work on fossil conservation. In this work, we focus on the protection of pterosaur fossils found in Hami, which are very sensitive to water. Four siloxane-based polymeric sols, including from tetraethyl orthosilicate and other three hybrid siloxane monomers, are prepared by controlled hydrolysis protocol. Their chemical and physical properties and performances as fossil protection materials are examined. Experimental data show that all sols have excellent permeabilities, decent reinforcement abilities, good resistance to light and heat aging. The organic moieties in the hybrids can also significantly increase the fossil’s hydrophobicity and reduce the cracking of the gels. The results indicate siloxane-based polymers can be very potential protection materials for fossils. And the hybrid polysiloxane sol containing epoxy function groups has overall the best performances.
Top left: severely degraded fossil due to water erosion, top right: structures of four sols Bottom: significantly improved fossil resistance to water after treated by silica sols, from left to right: treated by TEOS-TMPM-s, TEOS-TMPE-s, TEOS-BTME-s, TEOS-s and control sample.
Cong Wu,Bing Yin,Dongshuai Hou,Shaochun Li,Xinpeng Wang
Core-shell polymer coating is a significant means of improving the surface protection of cement-based materials. In this paper, a novel strategy for the paraffin-doped polystyrene acrylate-polysiloxane core-shell emulsions (CSP) are proposed by combining polyaddition and polycondensation reactions , integrating the superior corrosion-resistance of PSA emulsions with the high-hydrophobicity of siloxane emulsions. The CSP emulsions have excellent physical stability and rheological behavior , with a lower proportion of unsaturated bonds and lower content of chemically bound water. The core-shell structure promotes the formation of Si–O bonds between the polymer molecules and the cement matrix , and more conducive to the formation of new silicate crystals on the cement hydrate surface. Macroscopically, the surface energy of the cement samples treated with CSP coating is below 16.7 mJ/m 2 , while its superficial nanoscale papillae give a water contact angle of almost 140°. The capillary absorption coefficient of the Portland concrete treated with CSP coating can be decreased to only 2.09 g/(m 2 ·h 0.5 ). Meanwhile, the corrosion rate of Cl − and SO 4 2− on the cementitious materials are significantly inhibited by the CSP membrane, reducing the levels of Friedel's salt, ettringite and gypsum generated by ionic corrosion, respectively. Furthermore, the CSP membranes have excellent molecular structural integrity and high cross-linkage under acid/alkaline corrosion and photo-thermal aging, maintaining superior adhesion and corrosion resistance with the cement substrate.
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