NIPAM

Dithiocarbamatc 16 has been used to prepare low dispersity PMAA ( Mw 1 Mn-1.2).52 Photopolymerization of S in the presence of dithiocarbamate 16 also displays some living characteristics (molecular weights that increase with conversion, ability to make block copolymer). However, 17 appears to behave as a conventional initiator in S polymerization.53 The difference in behavior was attributed to the relatively poor leaving group ability of the 2-carboxyprop-2-yI radical. This hypothesis is supported by MO calculations. Dithiocarbamatc 17 was used to control polymerizations of MMA,54 HEMA54 and NIPAM.5... 

The synthesis of block copolymers by macromonotner RAFT polymeriza tion has been discussed in Section 9.5.2 and examples are provide in Table 9.9. RAFT polymerization with thioearbonylthio compounds has been used to make a wide variety of block copolymers and examples arc provided below in Tabic 9.28. The process of block formation is shown in Scheme 9.59. Of considerable interest is the ability to make hydrophilic-hydrophobic block copolymers directly with monomers such as AA, DMA, NIPAM and DMAEMA. Doubly hydrophilic blocks have also been prepared.476 638 The big advantage of RAFT polymerization is its tolerance of unprotected functionality. 

RAFT polymerization has been used to prepare poly(ethylene oxide)-/ /wA-PS from commercially available hydroxy end-functional polyethylene oxide).4 5 449 Other block copolymers that have been prepared using similar strategies include poly(ethylene-co-butylene)-6/oci-poly(S-eo-MAH), jl poly(ethylene oxide)-block-poly(MMA),440 polyethylene oxide)-Moe -poly(N-vinyl formamide),651 poly(ethylene oxide)-Wot A-poly(NlPAM),651 polyfethylene ox de)-b ock-polyfl,1,2,2-tetrahydroperfluorodecyl acrylate),653 poly(lactic acid)-block-poly(MMA)440 and poly( actic acid)-6focA-poly(NIPAM),4 8-<>54... 

Protein isolation with affinity precipitation has been discussed in detail by Mattiasson and co-workers (see, e.g. Galaev and Mattiassion, 1997) and they have provided an exhaustive tabulation. Polymers varied from alginate.s/chitosan to dextran to NIPAM. Examples of the used proteins are from trypsin, p-glucosidase, xylanase, alkaline protease, etc. It is remarkable that affinity precipitation can sometimes give results comparable to affinity chromatography. 

In the second step, amino-terminated PEO chains were finked to the reactive NIPAM copolymers by condensation reaction of the primary amine... 

Fig.5 Synthesis of the graft copolymers in two steps (/) copolymerisation of N-iso-propylacrylamide (NIPAM) and glycidylmethacrylate (GMA) or N-acryloylsuccinimide (NASI), and (2) grafting of PEO to the polymer backbone [170]... 

In this section, we review the properties of a series of PNIPAM-b-PEO copolymers with PEO blocks of varying length, with respect to the PNIPAM block. Key features of their solutions will be compared with those of PNIPAM-g-PEO solutions. PNIPAM-b-PEO copolymers were prepared by free-radical polymerisation of NIPAM initiated by macroazoinitiators having PEO chains linked symmetrically at each end of a 2,2/-azobis(isobutyronitrile) derivative [169,170]. The polydispersities of PEOs were low, enabling calculations of the number-average molar mass for each PNIPAM block from analysis of their H-NMR spectra (Table 2). 

The cloud points of the aqueous polymer solutions with c = 3 x 10-7 M were measured by turbidimetry. Among the copolymer sets, the cloud points of the solutions of block copolymers having the longer PEO block increased from 32 to 34 °C with decreasing molar ratio of NIPAM to EO. No difference between the copolymers having the short PEO block was observed their cloud point was approximately 33 °C regardless of the NIPAM-to-EO ratio. Thus, the length of the PEO block has a minor effect on the cloud point. 

Fig. 12 The evolution of the aggregate with polymer concentration or the molar ratio of NIPAM to ethylene oxide (EO) above the LCST [170]...

The temperature dependence of solutions of an NIPAM-styrene copolymer, PNIPAM-seg-St, of Mw = 13.3 x 106gmol 1 in which hydrophobic St segments were evenly spaced along the chain was investigated under high di-... 

A number of diblock copolymers of NIPAM and hydrophobic comonomers have been prepared by various groups and assessed in terms of micellar structure, thermosensitivity, and applications. For example, PS-fo-PNIPAM was shown to form either micelles consisting of a PS core and a PNIPAM corona, or vesicles. The assemblies were colloidally stable at elevated temperature [262-266]. 

Polymers BA Butylacrylate, CHP 3-chloro-2-hydroxypropyl, DADMAC Diallyldimethylammonium chloride, DMAEA Dimethylaminoethylacrylate,DMAEM Dimethylaminoethylmethacrylate, EM Epichlorohydrin Modified, EIMAOETMAC Hydroxymethacryloxyethyltrimethylammoniumc chloride, MAOEDMAC Methacryloxyethyldimethylammonium chloride, MAOETMAC Methacryloxyethyltrimethylammonium chloride, MDMAEM Methyldimethylaminoethylacrylate, M2VP l-methyl-2-vinylpyridinium bromide,M4VP l-methyl-4-vinylpyridinium bromide,NIPAM N-isopropylacrylamide,PEI Polyethyleneimine, Q Quaternary, VBTMAC Vinylbenzyltrimethylammonium chlroide,VP Vinylpyridinium. 

Ni-P adhesion, 9 705. See also Nickel phosphorus entries Ni-P alloys, solderability, 9 707, 708 NIPAm hydrogels, 13 738 Ni-P density, 9 705 Ni-P electrical resistivity, 9 706 Ni-P ferromagnetic properties, 9 706 Nipkow disk, 16 484 Ni-P mechanical properties, 9 706 Niranium N/N, base-metal dental alloy, 8 309t... 

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