Preparation And Application Of Healable Functional Gels Based On Poly(α-thioctic Acid)

Gel materials perform well and have attracted wide attention in application fields such as coatings,sensors,actuators,soft robots,and biomedicine.However,due to the limitation of gel mechanical properties,cracks are easily formed by external forces.These cracks may affect the integrity of gel network,resulting in the deterioration of the function and shorten the service life of gel.To solve this problem,endowing composite system gel with self-healing properties has become a research hotspot.In this paper,starting from a small molecule ofα-thioctic acid（TA）,and guided by the theory of intrinsic self-healing,healable composite system gels with magnetic and electrical functions were constructed through reasonable structural design and the composite of nanomaterials,and studied their properties and applications.A highly effective self-healing magnetic gel was constructed by using high temperature ring-opening polymerization（ROP）reaction of TA,hydrogen bonding,coordination of Fe Cl₃-carboxyl group and doping of Fe₃O₄ nanoparticles.The effects of Fe₃O₄ and Fe Cl₃ on the healing properties of magnetic gel were investigated.The rheological properties and plasticity of the self-healing magnetic gels were also studied.When the mass fraction of Fe₃O₄ was 3.3wt%and the mass of Fe Cl₃ was0.393 g（1/10 of TA）,the PTA-DIB-Fe/Fe₃O₄ magnetic self-healing gel showed excellent healing performance,and its healing efficiency can reach 100%within 10min.In addition,frequency scanning,step alternating experiments,and temperature rheological scanning revealed the correlation between the repair properties of magnetic gel and its structure.In this paper,the polyvinyl alcohol（PVA）,Borax,TA polymer（PTA）and Fe Cl₃were used to construct the composite system gel,and the composite system was doped with appropriate amount of multi-walled carbon nanotubes（MWCNTs）to realize the preparation of self-healing,hypertensile,high sensitivity conductive gel.The effect of TA mass fraction on the gel repair properties and mechanical properties of the composite system was studied.When the mass fraction of TA was 1 wt%,the conductive gel of the composite system could achieve a high repair efficiency of94±0.7%,and the tensile property was 3 times higher than that of PVA-Borax gel,which can be explain by the theory of energy dissipation.The electroremediation property and rheological behavior of the composite system conductive gel were studied.The electroremediation efficiency of the composite system gel was 97%in a short time（6 s）without external stimulation.The gel sensor based on the conductive gel was investigated.The PVA-B-PTA/MWCNTs composite gel strain sensor showed high elongation at break（1350%）,high sensitivity（11.50）and high stability（100cycles）.In addition,strain sensor was attached to the human joint to monitor human movement behavior,which verified its feasibility as a wearable sensor.To solve the low temperature freezing and water loss problems of gel based sensors,anti-freezing,monsting and conductive composite system organohydrogels（PVA-B-PTA-c MWCNTs）were constructed by using TA,PVA-Borax,carboxyl modified carbon nanotubes（c MWCNTs）and ethylene/glycol water（H₂O/EG）.The PVA-B-PTA-c MWCNTs organohydrogel demonstrated excellent low temperature resistance（-60℃）,long-term moisture retention（30 days）,excellent stability（400cycles）,and high electrical conductivity sensitivity(S=0.625 kpa^-1).In addition,the organohydrogel can sensitively detect different continuous pressure values in the operating range of 0～600 k Pa.The low temperature detection ability of the organohydrogel was verified by finger pressing and foot pressing,which provides a broader prospect for the development of flexible sensors in extreme environments.