The 11th Global Conference on Polymer and Composite Materials (PCM 2024)

Abstract: With the gradual depletion of shallow oil and gas resources, deep (>4,500m) and ultra-deep (>6,000m) oil and gas have become the main sources of oil and gas resources in China. With the advancement of technology, the drilling depth has been gradually increased. Two extra-deep wells with a design depth of over 10,000 m are being drilled in China. One of the wells has exceeded 10,000 m. However, the high temperature in the deep formation poses a great challenge to the temperature resistance of drilling fluids. Water-based drilling fluids (WBDF) are multistage dispersion systems of clay, weighting agent and a variety of chemical materials in water. Drilling fluid serves as “drilling blood” and plays a vital role in carrying and suspending drill cuttings, stabilizing wellbores, and lubricating and cooling drill bits during drilling-based engineering. Water-soluble polymers mainly regulate rheology and control filtration in drilling fluids, but their performance fails under high-temperature and high-salt conditions, which is a serious problem for drilling safety and efficiency. This presentation will focus on the topic of high temperature resistant polymers used in the drilling fluid. It will cover the technical challenges of deep well drilling, the challenges for polymers and the current status of research on high temperature resistant polymers. Finally, some research results on high temperature resistant polymers from our team will be presented.

Abstract: Degradable biomaterials have emerged as a viable alternative to permanent materials for regenerative bone medicine. Although Polycaprolactone (PCL) exhibits remarkable extensibility and toughness, its low elastic modulus and strength, hydrophobicity, and excessively slow degradation rate limit its application in orthopedics. Natural silk fibers with macroscopic continuity and highly ordered morphology are selected to reinforce PCL to satisfy the mechanical and biological requirements for bone grafts. In this talk, we discuss the design, fabrication, and bone graft application of fiber silk-PCL biocomposites.
Silk-PCL composites with 20%/40%/60% silk were fabricated via layer-by-layer assembly and hot-pressing, allowing facile incorporation of drugs. The fiber silk composites exhibited compatible modulus (1GPa) to the majority of bone tissues, high compressive strength (150MPa), high toughness, hydrophilicity, and water adsorption behavior. The 6-month in vitro degradation experiment showed that passive surface erosion and bulk hydrolysis of the silk-PCL composite by the aqueous environment is negligible, and the fiber-matrix interfaces remained robust. In the in vivo rat subcutaneous model, the degradation of silk composites is significantly accelerated via inflammatory cells mediated PCL dissolution from the surface. Fiber silks are proposed to modulate the inflammatory responses toward synchronized material degradation and tissue reconstruction. A rabbit tibial defect model shows a strong tissue-composite implant bonding, suggesting sufficient mechanical function and the regeneration of new bone.
The silk-PCL composites bring forward exceptional comprehensive mechanical performance and desirable degradation behavior in vivo through the coupled inflammatory modulation effects of silk and PCL. This work may herald the advent of a novel biomaterial for load-bearing bone repair.

Abstract: Perioperative diagnosis and residual focus clearance are difficult problems for solid tumors such as triple negative breast cancer. Polymer-based composite nanoparticles can drive or assist physicochemical reactions and biological effects in diagnostic processes, but multiphase reaction flow transfer and kinetic control are important challenges to improve response efficiency and specificity. Our group makes full use of melanin-like materials with synergistic molecular mode (based on phenol-quinone redox) and optical mode (based on electromagnetic effects of conjugated structures) to develop new composite materials. Aimed at two key scientific problems of " response modulation method for interface coupling and distance constraint of diagnosis and treatment elements" and "balancing engineering mechanism of confined activation and cascade transformation of active species", biochemical identification-response-amplification mechanisms and balancing engineering of active species are cross-fused in function transfer-synergy systems of composite nanomaterials. Homogeneous photoelectrochemical sensors for the detection of miRNA markers in tumor interstitial fluid with high reproducibility were developed by employing electron transfer cascade constrained by interface collision. Complex catalytic structures empowered with elementary transfer and efficient pore diffusion were designed to achieve a catalytic oxidation therapy system that efficiently overcomes tumor cell resistance. An interface-oriented control model and regulation paradigm for oxidative polymerization of melanin-like nanoparticles was established to develop a "contradiction complex" material that meets ROS balance engineering and inflammation control after phototherapy. The activity of infiltrated immune cells after activation and the efficiency of metastasis and recurrence inhibition was effectively enhanced. Finally, the key technical problem of "high-performance biosensor and combined ablation therapy driven by endogenous microenvironment and active materials" was broken through, and functional material construction strategies that accurately adapted to the complex response network modulation of the diagnosis and treatment process were formed. The above perioperative tumor auxiliary diagnosis and treatment materials with high efficiency and specificity, transmission coupling and material energy conversion flow synergy provide innovative solutions for the construction of intelligent nano-diagnosis and treatment systems.

Keywords: Composite Nanoparticles; Tumor Theranostics; Interfacial Processes; Catalysis Control; Cell Response

Acknowledgements: The work was supported in part by the National Natural Science Foundation of China (NSFC, grant nos. 22175027 and 21734002), the Natural Science Foundation of Chongqing (cstc2021jcyj-cxttX0002 and cstc2021jcyj-msxmX0178), project no. 2023CDJXY-051 supported by the Fundamental Research Funds for the Central Universities, and the 100 Talents Program of Chongqing University (J.Z.). The Analytical and Testing Center of Chongqing University is greatly acknowledged for helping with the characterization of materials.

Abstract: Polymer nanocomposites (PNCs) are widely used in automobile tire manufacturing industry. Concerning the long-standing energy crisis, designing and fabricating PNCs with both high strength and low energy consumption has gained numerous scientific interests. Inspired by nanoparticle-based supramolecular materials, the processed nanoparticles (NPs), as one of the synthetic monomers to build polymer chains, can essentially enhance the strength and stability of the filler network, thus achieving high strength and low energy consumption in the novel PNCs. We constructed the novel nanopolymer composites by embedding nanoparticles into polymer chains through coarse-grained molecular dynamics simulations. The structural, dynamic, mechanical and viscoelastic properties influenced by the content and size of the NPs are systematically explored. Compared to traditional PNCs, this novel PNCs exhibits a relatively higher glass transition temperature at the same content of NPs. Moreover, by analyzing the microstructure evolution during deformation, it was found that the formation of a zigzag-interlock structure with an intermediate strength, namely between the physical and chemical interaction, allows for a more prominent mechanical reinforcing efficiency than traditional PNCs. Besides, the NP size and the crosslink density play an important role in tailoring the mechanical properties. Finally, the dynamic mechanical properties of this novel PNCs, such as the loss factor and hysteresis loss, exhibit a much smaller energy dissipation than those of traditional PNCs, which is attributed to much lower friction between NPs-polymer brought by the more stable filler network. The slip rate between NPs-polymer can be reduced by 30%~60% in the nanopolymer system compared to the traditional PNCs. In general, our work confirms that this novel PNCs is an excellent candidate to exceed the traditional PNC by possessing a more significant nano-reinforcing effect and a much less dynamic hysteresis, opening a good avenue for the design and fabrication of next-generation elastomer nanocomposites tailored for green automobile tires.

Key words: nanopolymer, reinforcement, viscoelasticity, molecular dynamics simulation

Figure 1. This novel PNCs is an excellent candidate to exceed the traditional PNC by possessing a more significant nanoreinforcing effect and a much less dynamic hysteresis toward next-generation elastomer nanocomposites tailored for green automobile tires.