One Pot To Prepare Block And Graft Copolymers By Chemoenzymatic And The Study Of Self-assembly And Crystallization Behavior

One-pot chemoenzymatic synthesis of combining the enzymatic polymerization(eROP) reaction features of mild conditions, the green, the product has excellentoptical rotation, biodegradable and biocompatible advantages and atom transferradical polymerization (ATRP) and click chemistry advantages of controllable, lots offunctional monomers, themolecular chain segments can be designed; and also one-potsynthesis process simplified, energy efficient, and avoiding the separation andpurification of the intermediate compounds in multi-step operation, reducing thepollution caused by the solvent and the production cost. One-pot chemoenzymaticsynthesis technology promote the application of chemical enzyme synthesis methodsprovide a more simple, convenient, new technologies and new methods for thesynthesis of functional block polymers.In chapter2, we were successfully use of2,2,2-trichloroethanol triggered as abifunctional agent combination of eROP and ATRP in one-pot synthesis of thediblock copolymers PCL-b-PDMAEMA. By hydrolysis to remove the PCL segment.The success of the diblock copolymer PCL-b-PDMAEMA in one-pot bychemoenzymatic synthesis was proved by the NMR, GPC, WXRD technologies. Weuse pyrene as a fluorescent probe to study the critical micelle concentration (CMC) ofdifferent proportion of hydrophilic and hydrophobic segments copolymerPCL-b-PDMAEMA. With the rise of hydrophilic segments of PDMAEMA proportion,the CMC gradually decreases, which is due to the hydrophilic segments increasing.Then, we take advantage of tapping mode atomic force microscopy (tapping moldAFM) test morphology and size of the micelles dry state, the diameter is about150nm; and dynamic light scattering (DLS) investigated the hydrodynamic diameter of themicelles in aqueous solution is about335nm, which is fully extended in the swollenstate in aqueous solution. We use the POM and DSC to study the diblock copolymerPCL-b-PDMAEMA thermal performance and crystalline properties. We found withthe decreases of crystallized segment PCL in block copolymer PCL-b-PDMAEMA, ablock copolymer secondary melting temperature Tmdecreased gradually, graduallyincreased its crystallization temperature Tc, the crystallization enthalpy ΔHcgraduallyreduced, melting enthalpy ΔHmis gradually reduced, the apparent undercooling ΔTgradually reduced, the crystallinity Xcof the block copolymer is gradually decreased.PCL-b-PDMAEMA crystalline form under the polarizing microscope having a blackcross extinction phenomenon, the crystalline is spherulite, the growth rate is about16.6nm/s. We use DSC to study the PCL-b-PDMAEMA-1isothermal crystallizationkinetics, Avrami exponent n is about2, which is caused due to the copolymerPCL-b-PDMAEMA The non-crystalline segment PDMAEMA move for the the PCLcrystallization process of the crystalline segment PCL segment rearrangement play arole in obstructing the crystal growth space is compressed the dimension of the crystalgrowth is restricted. The crystallization activation energy was calculated by Arrheniusequation is about73.7KJ/mol.In chapter3.2-ethyl bromoisobutyrate was used as the initiator of ATRP, HEMAas the monomer of the ATRP reaction. The HEMA with its hydroxyl group was as theinitiator of eROP of ε-CL in one-pot chemoenzymatic system to synthesis brush typegraft copolymer PHEMA-g-PCL. By hydrolysis to remove the PCL segment usingNMR, GPC, to identified the polymer structure. We studied the brush-typecopolymers PHEMA-g-PCL self-assembly behavior in aqueous solution. we usedpyrene as a fluorescent probe by fluorescence spectrophotometric determination of theCMC of different proportion of graft copolymer PHEMA-g-PCL, we found that theCMC decreased with the improvement of the degree of grafting, This is due to theside chain of the copolymer of the brush type for the hydrophobic segment PCL grafthigh increase the proportion of hydrophobic segments, to make it easier to form micelles in a higher polymer concentration. Then, we take advantage of AFM testmorphology and size of the micelles dry state, and DLS investigated thehydrodynamic diameter of the micelles in aqueous solution. After analysis, we foundthat the particle size of the micelles formed by grafting a copolymer of high than lowdegree of grafting of the polymer to form a large particle size of the micelles, which isdue to graft the polymer of high hydrophobic segment. We use the POM and DSCstudy of the thermal and crystalline properties of the brush-type copolymersPHEMA-g-PCL. We found that the PHEMA-g-PCL-1and PHEMA-g-PCL-2thedegree of grafting is too small, the crystallization ratio of the components is small,and failed to form a crystalline copolymer. We found that in the study of thecopolymer PHEMA-g-PCL-3, its crystallization under a polarization microscopehaving a black cross extinction phenomenon, crystal type of spherulites the growthrate is about4.6nm/s. We use DSC to study of the copolymer PHEMA-g-PCL-3non-isothermal crystallization kinetics. Choosing the crystallization temperature of14-19℃, with Ozawa exponent m of the reduction of the crystallization temperatureis reduced from the close about3to about2for the polymer begins to crystallize isthree dimensional growth manner, crystal growth in the crystalline final restricted.The crystallization activation energy was calculated by Kissinger equation is about105.37KJ/mol.In chapter4.2-ethylbromoisobutyrate was used as ATRP initiator and GMA asthe ATRP monomer to synthesis PGMA. Sodium azide was used for ring-openingepoxy group to synthesis multifunctional macromoleculeinitiator PHAZPMA.Combined eROP and click reaction in one-pot chemoenzymatic to synthesisamphiphilic brush copolymer PHAZPMA-g-(PCL)(PEG) which were proved by useof IR, NMR, GPC. We studied the brush copolymer PHAZPMA-g-(PCL)(PEG)self-assembly behavior in aqueous solution. we used pyrene as a fluorescent probe byfluorescence spectrophotometric determination of a different proportion of graft brushcopolymer PHAZPMA-g-(PCL)(PEG) CMC. We found as the PEG content increasedthe CMC is gradually increased. Because of the side chain of the copolymer hydrophobic segments were PCL, the proportion of hydrophilic segments were PEG.it must be formed in a higher CMC to form micelles for more hydrophilic segments.Then, we use the AFM tests the morphology and particle size of the micelles dry state.After analysis, we found that the change in morphology from spherical to dendriticmorphology with the PEG content increased the morphology of the copolymer system.After analysis, we think that may be the first gathered in the copolymer to formspherical micelles, formation of dendritic pattern of gradual integration with thesolution of volatile spherical particles, and thus the formation of the system ofball-type dendritic morphology of the aggregates coexist. We used POM and DSCthermal properties and crystallization properties of the the brush type copolymerPHAZPMA-g-(PCL)(PEG). Through research, we found that crystalline PEG contentin the sample PHAZPMA-g-(PCL)(PEG)-1is small can not be formed. We foundonly the PCL crystallization which having a black cross extinction phenomenon,crystal type of spherulites the growth rate is about18.4nm/s. We take advantage ofDSC to study the copolymer PHAZPMA-g-(PCL)(PEG)-1non-isothermalcrystallization kinetics. By Jeziorny model fitting, the copolymer materialcrystallization process is divided into two sections of the primary crystallizationprocess and secondary crystallization process. We found that gradually increases asthe cooling rate increases crystallization rate constant Zt, Jeziorny crystallization rateconstant is almost unchanged, the average value of about1.1. Two crystalline phaseapparent Avrami exponent were1.06and2.52, nonisothermal crystallization processshows that the polymer is mainly in the primary crystalline phase nuclei formationand growth in the secondary crystallization process three-dimensional growthgradually formed spherulites. The Kissinger equation obtained crystallizationactivation energy for218.08KJ/mol.