| Free radical addition reaction is very important in UV curing.The cleavage type photoinitiator is excited to the excited state under irradiation of UV,resulting in the formation of free radicals.Benzoyl-like radicals are common photolysis products,which are added to the acrylate monomer,forming primary free radicals,and then lead to polymerization.At present,major studies on radical addition reaction focused on the field of kinetics.There are few studies on the free radical addition reaction from energy and reaction rate,which is calculated by transition state theory.The study of free radical addition reactions combined to biological hemostatic materials is currently not reported.In chapter 1,we investaged the free radical addition reaction of benzoyl radicals with amylene,allyl methyl ether and methyl acrylate by using the density functional theory.Through the energy and configuration change analysis,it was found that the activation energy of methyl acrylate was the smallest among the three reaction systems due to the small deformation energy.While the deformation energies of the amylene and allyl methyl ether are similar due to their similar deformation.The mechanism of free radical addition reaction is revealed by the interaction between radicals and olefin monomers.It is also demonstrated by visualization of weak interactions.Weak interaction analysis found that the weak interaction of the three reaction systems originated from the terminal C12-C14,and the Spike value of methyl acrylate was the highest.The old double bond breaking,and the new bond forming are depicted by Mayer bond order curve.Thebond-formation indices indicate that the transition state of the methyl acrylate reaction system is an “early” type transition state,which the reaction complex can be formed earlier,resulting in a smaller activation energy.Finally,the activities of the monomers were illuminated by Mulliken charge analysis,and the reaction rate was further confirmed that methyl acrylate reaction system has the smallest active energy and highest reaction rate.Hemostasis in vivo is one of the keys to the success of minimally invasive surgery(MIS).Solid hemostatic materials due to the low fluidity cannot pass the sheath tube of MIS apparatus,while liquid ones are restricted for their low adhesion resulting in unable to adhere to the tissue.In chapter 2,we use photoinitiators and sucrose monomers to yield the membrane quickly under ultraviolet irradiation to stop bleeding based on the mechanism of free radical addition reaction theory.A formula containing an alpha-hydroxyketone liquid photoinitiator(HMPP)and a multifunctional sucrose allyl ether monomer(SAE)was applied as a leading hemostatic material of MIS.A series of biological,physical and chemical experiments confirmed the feasibility.Quantum chemistry was used to calculate the chemical energy barrier;real-time fourier transform infrared investigate in vitro the formation process of film;animal experiment was performed to confirm the hemostatic effect and the cell experiment was conducted to examine the toxicity of the raw material.The result of quantum chemistry theoretically predicted that our system has the advantages of a smaller energy barrier and a shorter reaction time.Viscosity experiments and cytotoxicity experiments show that the formulation has a certain mobility and relative low toxicity.Although Real-Time Infrared results showed that the final conversion were lower than 60%,but in vivo hemostasis experiments confirmed that the mixed material(SAE+HMPP)can stop bleeding within50 seconds,which is not affected by blood flow.This has a competitive advantage in MIS compared to other hemostatic materials.In order to better explore the excited properties of photoinitiator,the excitation energy,molecular orbital and electron transition of the oxime ester initiator(OXE-1 andOXE-2)were also analyzed in chapter 3.It is found that the energy gap of OXE-1 is smaller than that of OXE-2,which reflects that the former is easier to be excited.Based on the result of electron transition density matrix,it can be found that OXE-1 and OXE-2can be excited from the ground state to the excited state are mainly caused by the electron transition on benzene rings and carbonyl groups.The excitation energy of the singlet state can be found to be greater than the triplet state,indicating that both electronic structures are more stable in the triplet state than that of the singlet state.OXE-1 and OXE-2 have similar vertical excitation energies,indicating that the potential energy of the excitation process is similar. |
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