The Self-assembly And Application Of Pyrrolidone-based Diblock Copolymers In Alcohol

Poly(N-vinyl pyrrolidone)(PNVP)is a water-soluble polymer that has excellent biocompatibility and strong coordination ability.It has been extensively utilized as a metal nanoparticle or nanorod stabilizer,carbon nanotube dispersant,drug delivery carriers.Many properties of PNVP polymer derive from its pyrrolidone functionalities.Although PNVP is widely used,there are some problems associated with the use of NVP,namely high reactive propagating radicals and poor copolymerization ability.To the best of our aware,the monodisperse PNVP and PNVP-based copolymer are quite limited.Recently,a new pyrrolidone-based monomer "N-(2-methacryloylxyethyl)pyrrolidone" has been successful polymerized via reversible addition-fragmentation chain transfer radical polymerization(RAFT).What’s more,the PNMP shows good thermo-responsive behavior which could improve the new foundations for a wider range of application.In this thesis,three kinds PNMP-based diblock copolymers have been synthesized by the RAFT radical polymerization.The main research focuses on the self-assemble behaviors of the amphiphilic copolymers in selective solvent and the applications in the preparation of nanoparticles.The core content includes that the PNMP-b-PMMA self-assemble into a thermoresponsive organogels in isopropanol and PMAA-b-PNMP is used as a temple to synthesis the hydroxyapatite.The main contents and conclusions are summarized below:Two categories of well-defined pyrrolidone-based diblock copolymers have been successfully synthesized via RAFT method.These polymers include:poly[N-(2-methacryloylxyethyl)pyrrolidone]-b-poly(methyl methacrylate)(PNMP-b-PMMA),poly(methacrylate acid)-b-poly[N-(2-methacryloylxyethyl)pyrrolidone](PMAA-b-PNMP).Their structrues were characterized by the gel permeation chromatography(GPC)and 1H NMR.The kenitic study on the NMP homopolymerization and chain extension of PNMP macro-CTA with MMA suggested the "living" character.A new series of amphiphilic pyrrolidone diblock copolymers poly[N-(2-methacrylaoyxyethyl)pyrrolidone]-block-poly(methyl methacrylate)(PNMPm-b-PMMAn;where m is fixed at 37 and n is varied from 45 to 378)is developed.Spontaneously situ-gelling behaviors are observed in isopropanol when n varies from 117 to 230,whereas only dissolution or precipitation appears when n is beyond this region.Further analysis reveals that uniform thermos-induced reversible gel-sol transitions are observed in those organogels,which is attributed to the disassembly from micellar networks to micelles as confirmed by electron microscopy and other techniques.The gel-sol transition temperature is highly dependent on n and increases as n increases.Conformational interactions analyzed using 1H NMR and 2D Noesy NMR suggest that the thermos-induced stretch of solvophilic PNMP segments within micelles and the sequencing variation in the isopropanol molecules are the major cause of the gel-sol transitions.Various poly(N-(2-methacryloylxyethyl)pyrrolidone-b-benzyl methacrylate)(PNMPn-b-PBzMAm)nanoobj ects have been prepared via reversible addition fragmentation chain transfer(RAFT)alcohol dispersion polymerization.The kinetic study on chain extension of PNMP macro-CTA with BzMA suggested the "living"character.1H NMR studies confirmed that the rate of BzMA polymerisation was significantly faster than by the solution polymerization.The final nanoparticle morphology is shown to be sensitive to the total solids content,the DP of the core-forming block(PBzMA)and also the mean DP of the stabilizer block(PNMP).However,the PD of PNMP segment play the critical role that affects the self-assembly behaviors of PNMPm-b-PBzMAn dramatically.Using PNMP39 and PNMP55 as a steric stabilizer,a range of nano-objects(spheres,worms or vesicles)can be accessed simply by tuning the DP of the core-forming PBzMA block.In contrast,using the PNMP64 stabilizer only produces spherical morphologies.More importantly,the formation mechanism of diversified aggregates of PNMPm-b-PBzMAn is explained form the viewpoint of the solvophilic-solvophobic balance of polymeric amphiphiles,rather than the widely employed molecular packing parameter theory in the PISA systems.The proposed new mechanism not only justifies the current results by a general method for the first time,but also forecasts a comprehensive illustration about the self-assembly behaviors by PISA.A series of HAps nanoparticles were synthesized by co-precipitation method in water using the PMAA-b-PNMP block polymer as the template.The pH、concentration of PMAA-b-PNMP and the DP of PNMP could effect the morphology of the HAp nanoparticle.The synthesized moruloid-like HAp nanoparticles exhibit a good ability in adsorption on CR dye molecules which has a high adsorption capacity(467 mg g-1).Kinetic and isotherm studies showed that pseudo-second-order model and Langmuir model could well describe the adsorption behavior.The CR adsorption on the synthesized HAps was a spontaneous process through the thermodynamic investigation.The result of FI-IR indicated that electrostatic interaction and hydrogen bonding are the main drivers in the adsorption process.