Preparation And Thermal Properties Of Novel Composite Phase Change Materials For Biomedical Applications

Human is homoiotherm.A keep rising or lowering body temperature will generate a lot physical illnesses and system disorders.Thus,reasonable regulation and control of the body temperature is crucial to the diseases closely related to the temperature.For instance,when winter comes,allergic rhinitis patients will have exacerbate symptoms.Clinical research shows when the temperature of the inhaled air in noses can continued for about 20 min above40?,the decongesting rhinocleisis and nasal congestion will be effectively relieved.In addition,when season changes,there will be a large increase in the incidence of a fever.For the fever,cold compress by the cold pack or towel is valid.Besides,due to the highly sensitive to the temperature,cancer cells can be killed by the local high temperature.Therefore,for the diseases greatly affected by temperature changes,they can be eased symptoms or cured by the effective control of the normothermia.Phase change materials?PCMs?generally refer to the substances having large latent heat of fusion with regard to melting and solidifying at a nearly constant temperature.The ability of PCMs to store and release large amount of heat energy in response to a small temperature change has attracted a great deal of attention in recent years,like solar thermal power generation and building energy conservation area.Herein,this research introduces PCMs to biomedical field as the ideal thermo-sensitive materials and develop the basic research of PCMs in biomedical application.Firstly,a novel paraffin/polypropylene hollow fiber phase change composite was prepared for the cure of allergic rhinitis through simple impregnation method,then the phase change composite was woven to be a thermal therapy mask and the thermal release performance was tested.Phase change tempetarure of the paraffin and the mass quality of the phase change composite were determined according to the clinical treatment request and thermophysical property of the phase change composite.To improve work efficiency,the thermal release performance of the phase change composite was systematically analyzed by numerical simulation.The phase change temperature and mass fraction of the phase change composite and the influence of convective heat transfer coefficient on its thermal release performance were theoretical analyzed and thus put forward the concept of available energy.In addition,to add breathability and aid comfort,a phase change composite based channel-type mask was designed.The thermal release performance of the channel-type mask was also analyzed by the same numerical calculation model.The result shows the paraffin/polypropylene hollow fiber phase change composite with good thermal stability and high latent heat was flexible and biodegradable.The result of numerical calculation shows available energy is determined primarily by mass fraction of the phase change material and thermal release performance is determined by the mass fraction and thermal conductivity,but mass fraction is the main factor.Moreover,the sensible heat of the phase change composite has little impact on its thermal release performance.This mathematic model could provide predictive design of the hot compress product,and thus reduce the experimental time and save labor costs;Numerical calculation result shows the thermal release duration of the channel-type mask?38 g RT44HC/polypropylene hollow fiber phase change composite?was2250 s above 40°C,which has great potential in in future clinic treatment of allergic rhinitis.Secondly,a dynamic vulcanization process method for the preparation of phase change oleogel was developed for the cold compress therapy of the childhood fever.A biodegradable OP10E/SEBS phase change oleogel with high latent heat was prepared by impregnation and plate vulcanization method.Then cooling release performance of the phase change oleogel was investigated by experimental and numerical method.Due to its excellent cooling release performance,a cooling hat based on the oleogel is designed.Based on the body heat balance equations and thermal properties of the cooling hat,numerical simulation on human thermal regulation during fever was investigated,and thus a data base about the mass of required oleogel for children was obtained.The numerical investigation results revealed that when the height,weight and level of fever reach the maximum concurrently,just small amounts?38 g?of the oleogel could bring down the fever,which shows great potential in cold compress therapy.In the end,phase change material was introduced to the drug delivery system due to its homoiothermy in the solid-liquid phase change process,and thus a paramagnetism mesoporous Fe₃O₄ NPs by the solvothermal method was prepared.Then the prepared PCM/PEG/DOX mixture was loaded to the mesoporous pores of the Fe₃O₄ NPs,and thus acquired Fe₃O₄@PCM/PEG/DOX drug delivery system by solvent evaporation method.Its drug release process was investigated in vitro by direct heating,applying AMF,and under NIR laser irradiation.It is found that,the loading amount of DOX in the Fe₃O₄@PCM/PEG/DOX system can be precisely controlled by just adjusting the ratio of the drug to the PCM/PEG mixture,and around 80%of DOX can be released in 1.5 h.In addition,due to the exist of PCM,the temperature around the local tissue can be precise controlled,preventing the empyrosis to the normal tissue.This novel drug release system shows great potential for the development of drug delivery systems.