Aliphatic-acid coating and nano chitosan nucleator synergistically regulate the performance of PMMA "bone-Locking" foam dressing used for emergency fixation of clavicle fracture.

Clavicle emergency fixation can prevent fractured end from piercing heart and lung organs, which is crucial for wounded life. Clavicle with complex structure, great individual differences, and adjacent to important organs, which places high-requirements on performance of fixation materials. Developing advanced clavicle fixation material is a prominent hot-topic in the field of emergency-engineering. We prepared a Polymethyl-methacrylate (PMMA) "bone-Locking" foam dressing via novel polymer foaming process. Innovatively used aliphatic-acid and bio-polar macromolecule nanoparticles to adjust structure in non-traditional self-curing polymer melts to achieve high-performance. Stearic acid coating was prepared on the surface of foaming agent can delay nucleation period, increasing the initial Polymer-Bubble interface viscosity and effectively retard nuclei growth and escape. Nano-chitosan was compounded synchronously to induce in-situ nucleation and construct polar hydrogen bonds between chains, improve the crystallinity of PMMA matrix, reduce the relaxation ability of PMMA molecular chains and increase the interface viscosity again to inhibit nuclei growth and escape, realizing spontaneous coordination between viscosity and the bubble holes formation process. Obtained high-performance foam with uniform and regular bubble holes structure eventually. More, Dynamic Dual-Variable Field Bubble-Growth Dynamics was proposed, revealing the Bubble-Growth behavior synergistic driven by Viscosity and Temperature theoretically, providing reference for improving theory in polymer foaming field. Prepared foam dressing can be directly and softly coated on clavicle and spontaneously conform to the contour of clavicle with remarkable precision, then quickly (3.5 min) curing into a lightweight (0.57 g/cm3), high-strength (40.5 MPa), breathable (224.73 mm/s) "Armor", showing great application value in wound emergency engineering. The developed foaming method and theory provide technical and theoretical value for polymer foaming system. The foam dressing provides a promising new scheme for fixing various wound sites and ensuring the life safety of the wounded at the emergency scene.