Efficient passive cooling technologies hold significant potential for applications in heat transfer, thermal conductivity, and energy concentration in high-power devices. However, common high-thermal-conductivity materials often suffer from poor biocompatibility and lack biodegradability, limiting their use in body surface cooling and wearable devices. Consequently, developing thermally conductive materials through green synthesis while ensuring biocompatibility and biodegradability has become a major challenge in body surface cooling. In this study, boron nitride particles modified with carbon quantum dots (CDs@BNOH) were synthesized as high thermal conductivity composite fillers, which were then incorporated into a potentially biocompatible silk fibroin hydrogel patch. The CDs@BNOH/SilMA patch exhibits a good and stable recyclable thermal conductivity of 0.77 W m–1 K–1, with a 15.38% increase in the overall thermal conductivity due to the modification with carbon quantum dots. Additionally, under simulated direct sunlight, the CDs@BNOH/SilMA patch demonstrated exceptional body surface cooling performance, reducing the temperature by 6.6 °C compared to the control group. This hydro patch not only exhibited potential biocompatibility and biodegradability but also demonstrated promising potential in body surface cooling applications.
Na Zhao,Chuanli Ren,Yong Shen,Shaofeng Liu,Zhibo Li
Degradable long-chain aliphatic polyesters are promising alternatives to polyolefins. The ring-opening polymerization (ROP) of ω-pentadecalactone (PDL) enables the synthesis of aliphatic polyesters with melting temperature close to low-density polyethylene (LDPE). However, this ROP reaction is of great challenge because of low ring strain of the PDL monomer. The occurrence of intra- and intermolecular transesterification reactions during ROP made it difficult to prepare well-defined block copolyesters for advanced properties. In this context, cyclic trimeric phosphazene base (CTPB) in combination with benzyl alcohol (BnOH) was proved to be an efficient initiator system for ROP of PDL, showing an excellent polymerization rate (TOF up to 600 h–1) at 80 °C. Well-defined diblock copolyesters, i.e., PPDL-b-PLLA, can be easily synthesized by sequential addition of PDL and l-lactide (L-LA). In contrast, sequential addition of PDL and ε-caprolactone (CL) or δ-valerolactone (VL) only led to the random copolyesters under the same conditions. On the other hand, CTPB is an inherent tribasic superbase and can be partially neutralized to decrease its basicity for better control over active lactones such as CL and VL. Hence, we introduced 0.33–1.0 equiv of benzoic acid (PhCOOH) relative to CTPB and demonstrated that it can diminish the transesterification during ROP of CL or VL. Based on this strategy, PPDL-b-PCL or PPDL-b-PVL diblock copolyesters were successfully prepared by sequential addition of monomers of CL or VL after ROP of PDL. The block copolyester structures were confirmed by the 13C NMR spectroscopy and DSC characterizations.
Yang Chen,Jie Zhang,Wenhao Xiao,Anfu Chen,Zhixian Dong,Jinbao Xu,Wenhua Xu,Caihong Lei
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) was used as organocatalyst to reinvestigate the ring-opening polymerization (ROP) of ε -caprolactone (CL) with benzyl alcohol (BnOH) initiator in bulk at 90 °C considering the unsuccessful ROP of CL at RT in previously reported publications. Kinetic study indicates that the PCLs could be well-designed with a controlled/living character of polymerization. The use of functional initiators, such as 2-hydroxyethyl methacrylate (HEMA), propargyl alcohol (PGA), 6-azido-1-hexanol (AHA) and methoxy poly(ethylene glycol) (mPEG) leads to end-functionalized PCLs. Accordingly, the block copolymerization of CL with δ-valerolactone (VL), trimethylene carbonate (TMC) and lactide (LA) successfully proceeded to give PCL- b -PVL, PCL- b -PTMC and PCL- b -PLA copolymers. Finally, the reaction mechanism was studied with DFT calculations and NMR measurements.
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