@article {1040,
	title = {Laser-light-scattering study of internal motions of polymer chains grafted on spherical latex particles},
	journal = {Journal of Physical Chemistry B},
	volume = {108},
	number = {48},
	year = {2004},
	note = {ISI Document Delivery No.: 875JUTimes Cited: 6Cited Reference Count: 35},
	month = {Dec},
	pages = {18479-18484},
	type = {Article},
	abstract = {Using atom-transfer radical polymerization, we have prepared core-shell particles by grafting thermally sensitive poly(N-isopropylacrylamide) (PNIPAM) chains on a spherical polystyrene latex core (with a radius of similar to287 nm) via the "grafting-from" approach. As the temperature increases from 25 degreesC to 35 degreesC, the PNIPAM shell shrinks from a thickness of 625 nm to 110 nm and the chain density near the core increases from 7.3 x 10(-3) g/cm(3) to 7.2 x 10(-2) g/cm(3). Using such core-shell particles, we have, for the first time, been able to study dynamics of long chains anchored on a particle in dilute dispersion by laser-light scattering. Our results showed that, besides the translational diffusion of the particle as a whole, there also exists an additional slow relaxation mode that is only observable at larger scattering vectors (q),which are presumably related to internal motions of the shell. In the fully swollen state, the relaxation rate of the slow motion (<Gamma>(slow)) is insensitive to the observation length (1/q); however, its contribution to the scattering intensity (A(slow)) increases as q increases. In the shrunken state, <Gamma>(slow) slightly decreases as q increases. <Gamma>(slow) can be scaled to the shell thickness (<L>(brush)) as <Gamma>(slow) proportional to <L>(alpha)(brush), with alpha = -2.5 +/- 0.2, which is smaller than the predicated value of 3.},
	keywords = {AQUEOUS ATRP, BRUSHES, CONFORMATION, DYNAMICS, GLOBULE TYPE TRANSITIONS, INTERFACE, LAYERS, MODEL, POLY(N-ISOPROPYLACRYLAMIDE), SIMULATION},
	isbn = {1520-6106},
	url = {<Go to ISI>://000225417200015},
	author = {Yang, C. and Kizhakkedathu, J. N. and Brooks, D. E. and Jin, F. and Wu, C.}
}
@article {866,
	title = {Molecular weight and polydispersity estimation of adsorbing polymer brushes by atomic force microscopy},
	journal = {Langmuir},
	volume = {20},
	number = {8},
	year = {2004},
	note = {ISI Document Delivery No.: 811CPTimes Cited: 23Cited Reference Count: 36},
	month = {Apr},
	pages = {3297-3303},
	type = {Article},
	abstract = {{We have estimated the molecular weight, M-n, and polydispersity, PDI, of densely grafted poly(N-isopropylacrylamide) (PNIPAM) brushes using a novel atomic force microscopy (AFM) approach. When compression of a polymer brush induced adsorption of multiple chains to an AFM tip, the resulting decompression force profile exhibited a maximum attractive force at a separation, L-m, that decayed to zero with increasing tip-sample separation. We have found that the separation L approximates the average contour length, L,, determined by gel permeation chromatography (GPC). The detection of a decaying attractive force at separations larger than L, suggests that chains of above average length sequentially break free from the tip as they are stretched away from the grafting surface. The shape of the decompression profile in this region approximately paralleled the cumulative weight fraction of the grafted chains determined by GPC. The fraction of chains of a given molecular weight determined from a single force curve fit a log-normal distribution, having a standard deviation that provided an estimate of the PDL We have characterized two PNIPAM brushes by this AFM technique as well as by GPC coupled to a multiangle laser light-scattering detector (MALLS). The values obtained by AFM-(1) Mn,(AFM) = (3.8 +/- 0.5) X 104},
	keywords = {ADSORPTION, AFM, CHAIN ELONGATION, ELASTIC PROPERTIES, PHASE, POLY(ACRYLAMIDE), POLY(N-ISOPROPYLACRYLAMIDE), SPECTROSCOPY, SURFACES},
	isbn = {0743-7463},
	url = {<Go to ISI>://000220750300044},
	author = {Goodman, D. and Kizhakkedathu, J. N. and Brooks, D. E.}
}
@article {894,
	title = {Plasma protein adsorption to surfaces grafted with dense homopolymer and copolymer brushes containing poly(N-isopropylacrylamide)},
	journal = {Journal of Biomaterials Science-Polymer Edition},
	volume = {15},
	number = {9},
	year = {2004},
	note = {ISI Document Delivery No.: 865ALTimes Cited: 13Cited Reference Count: 38Symposium on Gels, Genes, Grafts and Giants held in Celebration of the 70th Birthday of Allan HoffmanDEC, 2002Maui, HIUniv Washington Engineered Biomat NSF Engn Res Ctr},
	pages = {1121-1135},
	type = {Proceedings Paper},
	abstract = {Growing polymer chains from surface initiators in principle allows much more dense polymer surface layers to be created than can be produced by grafting of whole (self-excluding) chains. We have utilized aqueous atom transfer radical polymerization to graft a series of cleavable hydrophilic poly (N-isopropylacrylamide) (PNIPAM) homopolymers and block copolymers of substituted acry-lamides from polystyrene latex to give brushes of controlled MW and surface density. Average chain separations much less than their free solution radii of gyration have been achieved. Exposure to radiolabeled single proteins or to whole plasma and subsequent analysis by SDS-PAGE shows that PNIPAM brushes decrease protein adsorption relative to the latex surface or other substituted polyacrylamides. The PNIPAM brushes exhibit a second-order phase transition around 30degreesC as reflected by a decrease in the hydrodynamic thickness of the brush at higher temperatures. Total plasma protein adsorption is increased at 40degreesC compared to 20degreesC but there is significant differential adsorption behavior among the proteins detected by gel-electrophoresis analysis.},
	keywords = {ADSORPTION, BIOMATERIALS, block copolymer, CHROMATOGRAPHY, FIBRINOGEN ADSORPTION, grafted latex, I-125 radiolabel, MODEL, OXIDE), plasma protein, POLY(ETHYLENE GLYCOL), POLY(N-ISOPROPYLACRYLAMIDE), polymer brush, POLYMER BRUSHES, PREVENTION, SDS-PAGE, SELF-ASSEMBLED MONOLAYERS, SERUM-ALBUMIN ADSORPTION},
	isbn = {0920-5063},
	url = {<Go to ISI>://000224674600005},
	author = {Janzen, J. and Le, Y. and Kizhakkedathu, J. N. and Brooks, D. E.}
}
@article {910,
	title = {Synthesis of well-defined environmentally responsive polymer brushes by aqueous ATRP},
	journal = {Macromolecules},
	volume = {37},
	number = {3},
	year = {2004},
	note = {ISI Document Delivery No.: 771TWTimes Cited: 102Cited Reference Count: 56},
	month = {Feb},
	pages = {734-743},
	type = {Article},
	abstract = {Functionalized anionic polystyrene latex particles with ATRP initiators were synthesized by surfactant-free shell-growth emulsion polymerization of styrene and 2-(2{\textquoteright}-chloropropionato)ethyl acrylate (HEA-Cl). N-Isopropylacrylamide (NIPAM) was polymerized from these particles by surface-initiated aqueous ATRP using PMDETA/CuCl and HMTETA/CuCl catalysts to synthesize poly(N-isopropylacrylamide) (PNIPAM) brushes. The grafted latexes were characterized for molecular weight of the PNIPAM chains, grafting density, and hydrodynamic thickness of the grafted polymer layer. Molecular weights of the grafted PNIPAM chains depended on the monomer concentration, concentration of copper(II) complex, and the presence of external initiator in the reaction medium. M-n of the grafted chains increases with increase in the monomer concentration and decreases with addition of copper(II) complex and external initiator. The HMTETA/CuCl catalyst produces higher molecular weight chains than PMDETA/CuCl. Molecular weights from similar to50 000 to 800 000 with low polydispersities, between 1.25 and 1.4, were achieved. The grafting density of PNIPAM on the surface increases with increasing monomer concentration and decreases with addition of copper(II) catalyst and external initiator. Block copolymerization of N,N-dimethylacrylamide from PNIPAM-grafted latex demonstrated that the chains are terminated with a chlorine atom, and the grafting reactions are taking place by the ATRP mechanism. The hydrodynamic thickness (HT) of the grafted PNIPAM layer scales as DP0.66 (where DP = degree of polymerization) at constant grafting density (chains/nm(2)). The HT values for PNIPAM brushes are sensitive to temperature and salt concentration. Since the transition from extended coil to collapsed structure occurs over a range of temperature and salt concentration, it follows a second-order transition, as predicted by theory. The thickness of the collapsed brush is sensitive to the type of stimulus used to induce the phase transition.},
	keywords = {GLOBULE TYPE TRANSITIONS, INTERFACES, N-DIMETHYLACRYLAMIDE) BRUSHES, PARTICLES, POLY(N, POLY(N-ISOPROPYLACRYLAMIDE), PROTEIN, SILICA, SURFACE-INITIATED POLYMERIZATIONS, TEMPERATURE, TRANSFER RADICAL POLYMERIZATION},
	isbn = {0024-9297},
	url = {<Go to ISI>://000188803000010},
	author = {Kizhakkedathu, J. N. and Norris-Jones, R. and Brooks, D. E.}
}
