Microgel cationic

In a related application, polyelectrolyte microgels based on crosslinked cationic poly(allyl amine) and anionic polyfmethacrylic acid-co-epoxypropyl methacrylate) were studied by potentiometry, conductometry and turbidimetry [349]. In their neutralized (salt) form, the microgels fully complexed with linear polyelectrolytes (poly(acrylic acid), poly(acrylic acid-co-acrylamide), and polystyrene sulfonate)) as if the gels were themselves linear. However, if an acid/base reaction occurs between the linear polymers and the gels, it appears that only the surfaces of the gels form complexes. Previous work has addressed the fundamental characteristics of these complexes [350, 351] and has shown preferential complexation of cationic polyelectrolytes with crosslinked car-boxymethyl cellulose versus linear CMC [350], The departure from the 1 1 stoichiometry with the non-neutralized microgels may be due to the collapsed nature of these networks which prevents penetration of water soluble polyelectrolyte. 

Stars with high arm numbers are commonly prepared by the arm-first method. This procedure involves the synthesis of living precursor arms which are then used to initiate the polymerization of a small amount of a difunctional monomer, i.e., for linking. The difunctional monomer produces a crosslinked microgel (nodule), the core for the arms. The number of arms is a complex function of reaction variables. The arm-first method has been widely used in anionic [3-6,32-34], cationic [35-40], and group transfer polymerizations [41] to prepare star polymers having varying arm numbers and compositions. 

The first synthesis of star polymers with a microgel core was reported by Sa-wamoto et al. for poly(isobutyl vinyl ether) (poly(IBVE)) [3,4]. In the first step, living cationic polymerization of IBVE was carried out with the HI/ZnI2 initiating system in toluene at -40 °C. Subsequent coupling of the living ends was performed with the various divinyl ethers 1-4. 

Cationically-charged microgel particles Precipitation polymerization of NIPAM or NIPMAM with a crosslinker (MBA) and AEMH 200-1000 nm Cationic surface charge. Swelling capacity dependent on MBA amount [12]... 

The ODN adsorption onto cationic microgel poly(N-isopropylacrylamide) particles was reported to be dramatically affected by the salinity of the incubation medium [9] as illustrated in Fig. 6. The observed result was related to (i) the reduction in attractive electrostatic interactions between ODN molecules and the adsorbent and (ii) the drastic effect of ionic strength on the physico-chemical properties of such particles [17, 27]. In fact, the hydrodynamic size, the swelling ability, the electrokinetic properties, and the colloidal stability are dramatically affected by pH, salt concentration, and the medium temperature [27]. 

Gorelikov et al. [150] demonstrated a way to provokephotothermally modulated volume transitions in microgel particles in the near-IR spectral range. Gold nanorods with different aspect ratios (from 2 to 6) stabilized by cationic surfactant were inte-... 

Hu, L. et al.. Preparaton and characterization of novel cationic pH-responsive polyl A. iV -diincthylamino ethyl methacrylate) microgels, J. Colloid Interf. Sci., 311, no, 2007. 

FIGURE 12.19 Reduced electrophoretic mobility (Pg/p max) of cationic poly(NIPAM) and anionic poly(NIP-MAM) microgel latexes as a function of temperature (10" A/ NaCl). p axis measured far from the electro-kinetic transition temperature (Te x). 

FIGURE 12.28 The reduction adsorbed amount of nucleic acids onto high cationic polystyrene latexes and low cationic poly(NIPAM) microgel particles as a function of pH at 20°C and M ionic strength. (From Ganachaud, F. et ah, Langmuir, 13, 701, 1997. With permission.)... 

Figure 4.14. TEM images of alumina samples containing Pd nanoparticles and templated over cationic (a) and anionic (b) microgels. (Reprinted with permission from reference 57. Copyright 2003, American Chemical Society.)...

Figure 1.1. (a) Stmeture of the spherical polyelectrolyte brushes having cationic polyelectrolyte chains on their surface. The core consists of poly(styrene) and has diameters of approximately 100 nm. The chains are densely grafted to the surface of these cores by a grafting-from technique ( photoemulsion polymerization, cf. Ref. 24). (b) The core-shell microgel particles shown in a schematic fashion The core consists of poly(styrene) (PS) whereas the network consists of poly(iV-isopropylacrylamide) (PNIPA) crosslinked by JVdV -methylenebisacrylamide (BIS). 

Stimuli-Responsive Cationic Microgels and Hydrogels Based on Pofy(N, H-dimethylarninoethyl methacrylate)... 

---