Photo-curing 3D printing technique and its challenges

In recent ten years,3D printing technology has been developed rapidly.As an advanced technology,3D printing has been used to fabricate complex and high-precision objects in many fields.3D printing has several technologies.Among these technologies,photo-curing 3D printing was the earliest and most mature technology.In 1988,the first 3D printing machine which was based on photo-curing and called Stereo lithography Appearance(SLA)technology was produced by 3D system Corp.After 30 years of development,many new technologies based on photocuring mechanism emerged.Based on the different principle of pattern formation and character of printing technology,numerous photocuring 3D printing techniques,such as SLA,DLP,LCD,CLIP,MJP,twophoton 3D printing,holographic 3D printing and so on,have been developed.Photo-curing 3D printing has many advantages,such as high precision,smooth surface of printing objects,rapid printing speed and so on.Here,we would introduce five industrial photocuring 3D printing technologies,which are SLA,DLP,LCD,CLIP and MJP.The characters of the materials and the progress of the application of the technique in the biomedical field is also overviewed.At last,the difficulties and challenges of photo-curing 3D printing are also discussed.

Facile and robust strategy to antireflective photo-curing coating through self-wrinkling

We reported a facile and bio-inspired strategy for obtaining antireflective （AR） coating through polymerization-induced self-wrinkling. Upon irradiation of light, the complex wrinkle micro-patterns with different morphologies were generated spontaneously on the surface of coating during photo-cross- linking, which enables the photo-curing coating can decrease reflection. The resulting photo-curing coating exhibits a high transmittance over 90% and low reflection below 5% ～ 8%, with an efficiency anti- reflection of 4% ～ 7%; compared to the flat blank coating. The successful application of these AR coatings with wrinkles pattern to encapsulate the thin film solar cells results in appreciable photovoltaic performance improvement of more than 4% ～ 8%, which benefits from the decrease of the light reflection and increase of optical paths in the photoactive layer by the introduction of wrinkling pattern. Furthermore, the efficiency improvements of the solar cells are more obvious, with a remarkable increase of 8.5%, at oblique light incident angle than that with vertical light incident angle

Photo-cured phase change energy storage material with photo-thermal conversion, self-cleaning and electromagnetic shielding performances via the lamellar structure strengthened by segment rearrangement of dynamic disulfide bond

At present,phase change materials(PCMs)with single function hardly meet the needs of advanced intelligent materials in practical applications,and the multifunction integration is the current trend.However,photo-cured multifunctional PCMs are hampered by insufficient transparency due to adding functional fillers,such as carbon and metal materials.The novel strategy is necessary to overcome this limitation.Here,a photo-cured multifunctional PCM is prepared by using the design of a lamellar structure composing the photo-cured phase change polymer layer and the functional fillers layer.The curing of the phase change polymer is realized by the photo-induced"thiol-ene"click reaction,and reversible dynamic disulfide bonds are introduced into the PCM,which not only gives the phase change crosslinked network reprocessability,but also strengthens the interface layer by the chain rearrangement to form a stable composite structure.The carboxylated multiwalled carbon nanotubes(CCNTs)and silver nanowires(AgNWs),as functional fillers,give the PCM photo-thermal conversion,self-cleaning and electromagnetic shielding(EMI SE)performances.Its phase change latent heat and photo-thermal conversion can reach 105.2 J/g and 78.5%,and the water contact angle is 142°with self-cleaning performance.In addition,due to the dense and well-developed conductive path formed by AgNWs layer on the PCM surface,the EMI SE effect can reach 39 dB with only 6.3%(in mass)filler content and 7.2%phase change latent heat loss.As far as we know,this is the first report about photo-cured PCMs with self-cleaning,photo-thermal conversion and EMI SE performances.