Hydrophobically modified poly

Akagi T, Higashi M, Kaneko T et al (2005) In vitro enzymatic degradation of nanoparticles prepared from hydrophobically-modified poly (y-glutamic acid). Macromol Biosci 5 598-602... 

Chung, J. E., Yokoyama, M., Aoyagi, T., Sakurai, Y., and Okano, T. Effect of molecular architecture of hydrophobically modified poly(A-isopropylacrylamide) on the formation of thermo-responsive core-shell micellar drug carriers. J. Contr. Rel, 1997, 53, 119-130. 

P. Perrin and F. Lafuma Low Hydrophobically Modified Poly (Acryhc Acid) Stabilizing Macroemulsions Relationship Between Copolymer Structure and Emulsions Properties. J. Colloid Interface Sci. 197, 317 (1998). 

Murugan E, Sherman RL Jr, Spivey HO, Ford WT. Catalysis by hydrophobically modified poly(propylenimine) dendrimers having quaternary ammonium and tertiary amine functionality. Langmuir 2004 20 8307-8312. 

Sayed-Sweet Y, Hedstrand DM, Spinder R, Tomaha DA. Hydrophobically modified poly(ami-doamine) (PAMAM) dendrimers their properties at the air-water interface and use as nanoscopic container molecules. J Mater Chem 1997 7 1199-1205. 

Liu RCW, Cantin S, PerrotFet al (2006) Effects of polymer architecture and composition on the interfacial properties of temperature-responsive hydrophobically-modified poly(Ar-iso-propylacrylamides). Polym Adv Technol 17 798-803... 

In this review, hydrophilically and hydrophobically modified poly(N-iso-propylacrylamide) (PNIPAM) copolymers are mainly used to illustrate how amphiphilic copolymer chains can fold from an extended random coil to a collapsed globule in extremely dilute solutions and associate to form a stable mesoglobular phase which exists between single-chain globules and macroscopic precipitation. The copolymers used can be prepared by free-radical reaction. 

It was also observed that nonionic amphiphilic ABA polymers (e.g., PEO-PPO-PEO) [200,205], polycations (e.g., quaternized poly(4-vinylpyridine) [214] and hydrophobically modified poly(N-isopropylacrylamide) [204] are able to accelerate translocation from the inside leaflet to the outside leaflet ( flip-flop ) within... 

FIG. 6 Emulsion type diagram of ra-dodecane-water emulsions ( = 0.5) stabilized with hydrophobically modified poly(sodium acrylate)s effect of changing the degree of grafting and type of the graft (single versus twin-tailed). Salt is used as a tool to estimate the copolymer HL properties. (From Ref. 152.)... 

Only a few studies about aqueous films of amphiphilic random polyelectrolytes are reported in the literature. Millet et al. [239-241] have investigated by x-ray reflectivity the behavior of vertical free-standing films (Figure 29) of a series of hydrophobically modified poly(acrylic acid) sodium salt (HMPAANa) and poly(acrylic acid) (HMPAAH). The chemical structure of the polymer was presented in Sec. II.C (Eq. 2a). One of the aims of this work was to determine the microscopic structure of the films to explain the (macroscopic) stability behavior of the dodecane-in-water emulsions studied by Perrin et al. [188,189], who used the same series of amphiphilic polyelectrolytes as primary emulsifiers. The aqueous polyelectrolyte films have been used as model systems for the interstitial films separating two neighboring oil droplets of an emulsion creamed layer. The authors have assumed that the oil/water interface encountered in emulsions was suitably described by the air/water interface of the films. The HMPAANa and HMPAAH co-... 

Perrin P, Monfreux N, Dufour AL, Lafuma F. Highly hydrophobically modified poly electrolytes field variables to control emulsion type. Colloid Polym Sci 1998 276 945-948. 

Perrin P, Lafuma F, Audebert R. Emulsions stabilized with hydrophobically modified poly(acrylic acid). Progr Colloid Polym Sci 1997 105 228-238. 

Wang TK, Iliopoulos I, Audebert R. Aqueous solution behavior of hydrophobically modified poly(acrylic acid). In Shalaby SW, McCormick C, Butler GB, eds. Water-Soluble Polymers Synthesis, Solution Properties, and Applications. ACS Symposium Series 467, 1991 218-231. 

The subject of surfactant-modified, water-soluble polymers, briefly discussed in Water-Soluble Polymers, is addressed in the last three sections (Chapters 16-28) of this book. These associative thickeners are covered in detail, ranging from the maleic acid copolymers of variable compositions introduced in various commercial markets in the early 1960s to the most recent entries (that is, in the open literature), hydrophobe-modified poly (acrylamide). Chapter 23 is complementary to the spectroscopic studies in Chapters 13-15 it explores new approaches to understanding associations in aqueous media. The three hydrophobe-modified polymers that have gained commercial acceptance in the 1980s, (hydroxyethyl)cellulose, eth-oxylate urethanes, and alkali-swellable emulsions, are discussed in detail. In particular, hydrophobe-modified (hydroxyethyl)cellulose, which is... 

Hydrophobically modified poly(acrylic acid) (HMPAA) thickeners, however, contain a certain proportion of long-chain alkyl groups (usually within Cs to C22 chain lengths). These alkyl groups set the hydrophobically modified polymers apart from their unmodified counterparts because they provide sites that allow anchoring of the polymer at an oil-water interface by hydrophobic interaction. The modified polymers, therefore, should behave as... 

In the initial phase of this work, attempts were made to prepare emulsions of 5% mineral oil in water by using only poly (acrylic acid) thickeners. The mineral oil was a pure clear, white grade with a viscosity of 100 mPa s at room temperature. Polymers A and B from the studies reported in the first half of this chapter were screened for their ability to emulsify the oil. In addition, two other grades of poly (aery lie acid) thickener (types C and D, with number-average molecular-weights of 1.25 million and 3 million, respectively) (1), and a hydrophobically modified poly (aery lie acid) were studied. 

The optimum concentration of this particular hydrophobically modified poly(acrylic acid) for emulsion stability appears to be 0.4%. This level gives emulsion stability over the pH range 3 to 9 at oil loadings up to 20% by weight. At 0.2 and 0.6% of the polymer, however, instability of the emulsion occurs at pH values higher than 8 (Figure 20). 

Effect of Electrolyte, Emulsions stabilized with hydrophobically modified poly(acrylic acid) are sensitive to electrolytes. Upon contact with a brine solution, emulsion stability is immediately lost, and rapid coalescence of the oil droplets ensues (Figure 23). This instability can be understood by consideration of the Donnan equilibrium of counterions in polyelectrolytes (discussed earlier in this chapter). Addition of salt causes collapses of the polyelectrolyte microgels that are adsorbed at the oil-water interface. Shrinkage of the microgels could conceivably lead to immediate loss of stability, as depicted schematically in Figure 24. 

Hydrophobically modified poly(acrylic acid) thickeners do show efficacy as primary emulsifiers. These emulsions, although stable for long periods will break and coalesce almost instantly when electrolyte is introduced into the aqueous phase. 

Ringsdorf H, Sackmann E, Simon J, Winnik FM. Interactions of liposomes and hydrophobically-modified poly-(N-isopropy-lacrylamides) an attempt to model the cytoskeleton. Biochim Biophys Acta 1993 1153 335-344. 

J. Kevelam, J. B. F. N. Engberts, M. J. Blandamer, B. Briggs, P. M. CnUis, Anchoring of hydrophobically modified poly(sodium acrylate)s into DDP vesicle bilayers hydrophobic match and mismatch, Colloid Polym. ScL, 1998, 276, 190-194. 

MYL Mylonas, Y., Bokias, G., lliopoulos, L, and Staikos, G., Interpolymer association between hydrophobically modified poly(sodium aciylate) and poly(Y-isopropyl-aciylamide) in water The role of hydrophobic interactions and polymer structure,... 

Effing JJ, Kwak JCT. 1995. Photoswitchable phase separation in hydrophobically modified poly(acrylamide)/surfactant systems. Angew Chem Int Ed Engl 34(1) 88 90. 

Effing JJ, McLennan IJ, Kwak JCT. 1994. Associative phase separation observed in a hydrophobically modified poly(acrylamide)/sodium dodecyl sulfate system. J Phys Chem 98(10) 2499 2502. 

Figure 11 Generic structure highlighting various hydrophobically modified poly(acrylic acids).

Figure 12 Poly(styrene-a/ -maleic anhydride) and hydrophobically modified poly(styrene-a/f-maleic anhydride).

Gosselet NM, Beucler F, Renard E, Amiel C, Sebille B (1999) Association of hydrophobically modified poly (N,N-dimethylacrylamide hydroxyethyhnethacrylate) with water soluble p-cyclodextiin polymers. Colloids Surf A Physicochem Eng Asp 155 177-188. doi 10.1016/80927-7757(99)00026-6... 

Iliopoulos, I., Wang, T. K. and Audebert, R., Viscometric evidence of interaction between hydrophobically modified poly(sodium acrylate) and sodium dodecyl sulfate, Langmuir, 7, 617-619 (1991). 

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