Design,Preparation And Application Of Zwitterionic Polymers With Strong "Anti-polvelectrolyte Effect"

Zwitterionic polymers have demonstrated their ideal biocompatibility,hydration,and "anti-polyelectrolyte effect" for many applications such as tissue engineering,drug release,bio-implants,biosensors,and interfacial friction/lubrication.In this thesis,we studied the salt response of zwitterionic polymer and designed a class of zwitterionic polymers with strong "anti-polyelectrolyte effect".The effect of ion concentrations,types,and structure of zwitterion on "anti-polyelectrolyte effect"and protein adsorption were systematically investigated.A bilayer hydrogel actuated by ion based on "anti-polyelectrolyte effect" was fabricated.Firstly,a kind of zwitterionic monomer named 3-(1-(4-vinylbenzyl)-1 H-benzo[d]imidazol-3-ium-3-yl)propane-1-sulfonate(VBIPS)was designed and synthesized,and prepared polymer brush by using surface-initiated atom transfer radical polymerization(SI-ATRP).The surface wettability,friction,and protein adsorption/desorption properties in water and brine were systematically explored,respectively.The results showed that the polyVBIPS polymer brush collapsed in water,while stretched in brine.By regulating ion concentrations and types,the surface of polymer brush reversibly switched from hydrophobicity(?56°)to hydrophilicity(?320),ultrahigh friction(??3.7)to superior lubrication(??10-3),and high protein adsorption(?145 ng/cm2)to low adsorption(?0.23 ng/cm2)respectively.In order to figure out the relationship between zwitterionic structure and"anti-polyelectrolyte effect",a series of polyzwitterionic brushes with different cationic moieties in their monomeric units and carbon space lengths(CSLs)between cation and anion were designed and synthesized via SI-ATRP.The surface wettability,friction,and protein adsorption/desorption properties which influenced by zwitterionic structure were systematically explored,respectively.The results showed that both cationic moieties and CSLs could affect the "anti-polyelectrolyte effect".The monomer with quaternary ammonium and long carbon space lengths(such as CSLs=3,4)exhibited high reactivity and chain growth rate.Moreover,different kinds of cations in zwitterionic unit leaded to different wettability of polyzwitterionic brushes in water,but the anti-polyelectroyte effect was not comprised.CSLs,however,exhibited significant effect on both wettability and anti-polyelectrolyte effect of the polyzwitterionic brushes.Specifically,polyzwitterion with carbon spacer length of Cl showed a strong intra/inter chain interaction,not only resulting in high water contact angle and surface friction,but also leading to an inert salt-responsive anti-polyelectrolyte behavior.Herein,polyMETAC/HEAA-polyVBIPS bilayer hydrogels were prepared by combining polyVBIPS with strong "anti-polyelectrolyte effect" and polyMETAC with "polyelectrolyte effect".Due to the opposite salt response between polyVBIPS and polyMETAC,the hydrogels exhibited wide range of bidirectional bending rapidly under synergistical actuation,the bending angle could be changed from-180° to?150°.Moreover,the reversible bending behavior could be achieved multiple times by switching water and salt solution.The bending orientation and degree of the bilayer hydrogel is driven by the opposite volume changes between the volume shrinking(swelling)of polyMETAC and swelling(shrinking)of polyVBIPS.In addition,a smart gripper of this bilayer hydrogel could accomplished the ability of"grasp-move-release" process.Moreover,large different polarities and polymerization activitis between polyVBIPS and polyNIPAM were selected to prepare bilayer hydrogels by "one pot"method.Such method showed simple and universal characteristic.Meanwhile,a multi-responsive behavior was introduced based on opposite salt/temperature response between polyVBIPS and polyNIPAM.The effect of weight ratio of NIPAM/VBIPS,ion concentration/types,temperature,and the thickness of hydrogel on bending behavior were systematically investigated,respectively.The results showed that a bilayer structure could be obtained by regulating weight ratio of NIPAM/VBIPS(<50%).Due to the opposite salt and temperature response between polyVBIPS and polyNIPAM,the bilayer hydrogels exhibited reversible and wide range of bidirectional bending rapidly under synergistical actuation.The bending angle could be changed from?-380° to-210° in response to ion situation,and from?-350° to-370° in response to temperature stimulation,respectively.Besides,the mechanical properties of bilayer hydrogel had been significantly promoted after external stimuli,which means such bilayer hydrogel has potential application in smart materials.