Combined Chain-and Step-growth Dispersion Polymerization In One-pot Toward Patchy Particles With Hard Body And Soft,Clickable Patches

Patchy particles(PPs)are defined as a class of particles with one or more chemically or physically constructed domains.There are directional interactions among patches or between patch and other materials.This endows PPs with many special functions and makes them perfect candidates for many applications,such as bulding blocks for hierarchical structured materials,solid surfactants,drug delivery systems,sensors,etc.UP to now,a variety of strategies have been developed for fabricating PPs,including microfluidic-assisted method,template-assisted approach,selective surface modification technique,phase separation process,etc.Among them,seed phase separation induced by swelling,temperature-increasing and polymerizing is recognized as a widely used approach to produce PPs with tunable morphology at high yelds.However,this technique involves multiple steps and the functionalization of each patch is difficult during this process.In our recent studies,we developed a one-pot dispersion polymerization(Dis.P)method(two-,one-step addition)to synthesize PPs,taking the growing particles during Dis.P as dynamic changing seeds,and tuning their swellability and cross-linking drgee.Combining click reaction,we flexibly tuned the mophorlogy,structure and composition of newly formed domain in PPs,but did not systematically investigate this process.Traditionally,spherical and PPs are mainly produced via strategies based on radical chain-growth polymerization.Recently,some researchers began to fabricate spherical polymer particles directly using step-growth click polymerizations in heterogeneous systems.Click polymerization has attractive features in synthesis of particles,including mild conditions and flexible functionalization,but glass transition temperatures(Tg)of the resultant particles are low,and so far,there has been no examples showing the production of non-spherical or PPs by heterogeneous click polymerization.In this thesis,PPs with controllable mophorlogy,structure and composition are fabricated by incorporating thiol-ene step-growth polymerizations into chain-growth Dis.P of styrene(St)in one-pot,and some functionalizations and applications of resultant particles are investigated.Main issues are described as follows:1.Dis.P is performed in a mixture of methanol and deionized water(MeOH/H20=6/4),using monomers of St and sodium p-styrene sulfonate(NaSS),and initiator of azobis(isobutyronitrile)(AIBN).Particles with a hard body(PSt,higher Tg)and soft shell,one or more dimples or one or more bulges(click polymer,lower Tg)are generated by adding thiol-ene click monomers during polymerization of St.Some factors,including click monomer addition time,amounts,feed ratio and types,are investigated to clarify their effects on morphology,structure and composition of PPs.2.Particles morphorlogy and composition evolutions,and polymerization behaviors after the addition of click monomers are investigated via SEM and TEM observations,gel contents and monomers conversion measurements,and FTIR analyses.The formation mechanism of PPs is discussed:the differences in Tg and hydrophilicity between PSt and click polymers facilitate phase separation,and lead to PPs formation.The off-stoichiometric polymerizations between thiol and ene even under stoichiometric feeding ratio are revealed.This contributes the presences of excess-SH or-C=C-groups on/in patches.3.Magnetic nanoparticles(NPs)are attached on the hard PSt body utilizing-SO3-groups on it,and Ag NPs are loaded on the soft click polymer patches using-SH groups on them.The click reaction between the excess-SH or-C=C-groups on patches and clickable monomers makes the patches post-modified,and produces fluorescent labeled,superhydrophobic or hydrophilic particles.Furthermore,superhydrophobic or hydrophilic particulate films are formed.