Construction Of An Innovative Organic Afterglow Nanoprobes And Its Application In The Precise Imaging And Therapy Of Tumors

Water freezing is a common phenomenon in nature,which would cause very serious harm to people’s daily life,cryopreservation of cells or organs,electric transportation system,aerospace or orther fileds.By studying from the creature living in cold environments,people have find that the chemical structure,hydrophilicity,aggregation state,size,and microscopic morphology of these biomaterials are the key factors controlling the nucleation of ice crystals and inhibiting the growth of ice crystals,which also provides design ideas for the synthesis of artificial antifreezing and anti-icing materials.Polymerization-induced self-assembly(PISA)has been widely used to prepare polymorphic nanoparticles and to regulate the chemical structure,hydrophilicity,aggregation state,size,and microscopic morphology of nanoparticles through the controllable design of molecular chain structure and sequence.Especially reversible addition-fragmentation chain transfer polymerization(RAFT)-mediated PISA has been applied to prepare a variety of multifunctional amphiphilic block copolymers due to many advantages such as mild polymerization conditions,wide applicability of monomers,and good controllability.In this thesis,RAFTPISA was used as the main polymerization means,and a series of polymorphic nanoparticles with anti-freezing properties were prepared by introducing responsive RAFT reagents,designing and synthesizing branched chain-modified functional monomers.In the mean time,a series recyclable fluorine-containing anti-icing coatings were prepared by designing the structure of molecular chains as well as by introducing functional monomers.The main work is as follow:(1)Applying the double end-group responsive RAFT reagent with RAFT-PISA,a series of polymerization pH-responsive PDMAA-bPDAAM-b-PDMAA ABA-type polymorphic nanoparticle copolymers were successfully prepared by using N,N’-dimethylacrylamide(DMAA)as the hydrophilic A-block and diacetone acrylamide(DAAM)as the hydrophobic B-block triblock.When PDMAA is polymerized at a degree of polymerization of 56 and pH = 2.5,the richest nanoparticle morphology transitions can be obtained with the growth of hydrophobic block PDAAM:spheres-peanuts-worms-tadpoles-vesicle clusters-large composite vesicles(LCVs).The diversity of morphologies decreases with increasing pH,and only spherical nanoparticles are obtained at pH = 8.By changing the terminal carboxyl group of the RAFT reagent to benzyl and monitoring the kinetics of the polymerization process,it was found that the pH-responsive properties of such ABA triblock copolymer nanoparticles mainly originated from the control of the initial assembled particle morphology by the ionization of the terminal carboxyl group at the early stage of polymerization.The phase diagrams at different pH also revealed that the lower the pH of this system,or the shorter the length of the hydrophilic block,the more likely to have advanced morphology through RAFT-PISA.(2)The effect of particle morphology on ice inhibition properties was investigated by using multi-morphlogy nanoparticles of which the hydrophilic block has no IRI activity.The ice recrystallization inhibition(IRI),dynamic ice shaping(DIS),single crystal growth and the bound water content of PDMAA-b-PDAAM-b-PDMAA tri-blocked nanoparticles.The results showed that the hydrophilic PDMAA block did not specifically bind to ice and have no IRI activity,but the self-assambled nanoparticles with PDMAA block have IRI activity,which indicated the morphology-dependent IRI activity.Further analysis of size,morphology,packing parameter,fractal dimension,concentration,pH,and end group reavealed that the IRI activity of such amphiphilic ABA block copolymers increased with the increase of the size over a certain range.When the size reached a certain level,the IRI activity increased with the increase of the packing parameter which reflect the hydrophilicity,i.e.,the obtained largesized vesicle clusters had the best IRI activity.Meanwhile,DIS experiments revealed that one-dimensionally oriented tadpole and vesicle cluster nanoparticles have a weak inducing effect on the ice crystal growth,which will make the ice crystal grow into a rod shape.The bound water analysis indicate that the large-size vesicle clusters not only have good IRI activity,but also can reduce the water freezing temperature to some extent.(3)To further investigate the effect of hydrophilic blocking on the IRI activity,on the basic design idea of bionic structure of poly(threonine)polypeptide,four modifided acrylamide have been synthesized: alaninemodified monomer(Ala A),threonine-modified monomer(Thr A),serinemodified monomer(Ser A),and(2-hydroxypropyl)methacrylamide(HPMAm).Among four monomers,PSer A and PHPMAm homopolymers possessed good IRI activity without being assembled into nanoparticles,and this IRI activity was further enhanced after PISA with DAAM as the hydrophobic monomer,which exhibited much better IRI activity than that of PAla A-b-PDAAM and PThr A-b-PDAAM nanoparticles in the same spherical nanoparticles.After replacing the hydrophobic block of PHPMAm-b-PDAAM with hydroxypropyl methacrylate(HPMA),PHPMAm-b-PHPMA was able to assemble into large-sized vesicles and lamellar nanoparticles with very excellent IRI activity at [PHPMAm] = 1mg/m L while MLGS below 10%.DIS,single ice crystal growth experiments also verified that PSer A and PHPMAm have specific binding to ice crystals,and this binding effect is enhanced with the increase of particle size and surface area.These modified nanoparticles with cebinding hydrophilic block have a greatly enhanced ice suppression effect,and excellent ice suppression properties can be obtained after assembled into large-scale advanced morphologies.(4)A series of fluorine-containing two-block copolymer emulsions that can be crosslinked at different blocks were synthesized using RAFTPISA emulsion polymerization while using acrylic acid(AA)as the hydrophilic monomer,hexafluorobutyl acrylate(HFBA)as the hydrophobic monomer,and DAAM as the crosslinkable monomer.The latexes were used to obtain crosslinked films with good mechanical properties,surface properties,anti-icing properties using a dihydrazide cross-linking agent,3,3’-dithiodipropionylhydrazide(DTDPH)which contains dynamic disulfide bonds.At the mean time,due to the presence of disulfide bonds,these crosslinked films were successfully decrosslinked in aqueous(alcohol)solution by a reductant with a recovery rate of more than 70%.This block fluoropolymer system presents a new idea for the design and synthesis of fluorine-containing high-performance anti-icing materials,and also provides a new solution for the mitigation of fluorine pollution and the recycling of fluorine-containing materials.