Synthesis of thermoassociative copolymers

Reversible Thermoassociation of Water-Soluble Polymers

“…2), these new copolymers were synthesised by grafting monoaminated LOST chains on hydrophilic macro molecules containing a minimum amount of carboxylic functions (Fig. 6) [16] and [26]. This reaction requires the presence of a coupling agent (e.g.…”

“…N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide, dicyclohexyl carbodiimide] and can be realised either in water or in an aprotic organic solvent (NMP, etc.) [14,15,16] and [26]. So as to avoid any cross-linking reaction in presence of difunctional LCST chains, the polymer concentration of the solution is kept below its critical value C*.…”

A novel thermoviscosifying water‐soluble polymer: Synthesis and aqueous solution properties

“…In the semidilute regime, hydrophobic clusters involving LCST grafts covalently linked to different water-soluble backbones should induce above T ass the formation of physical crosslinks between the mainchains, giving rise to a viscosity enhancement macroscopically. Basically, two types of thermosensitive functionalities were introduced onto polymer backbones with grafting technique: one was polyethylene (PEO) or copolymer of PEO and poly(propylene oxide) (PPO) that was grafted via a coupling reaction onto the mainchains of a low-molecular weight hydrosoluble parent polymer, for example, poly(acrylic acid) (PAA), 34,36 PAM, 37 copolymer of AA and 2-acrylamido-2-methyl propanefulfonic acid (AMPS), 38 terpolymer of AM, AMPS, and N-ethyl vinyl acrylamide, 37 even the natural polysaccharide such as carboxymethylcellulose, aliginate, and carboxylated dextran 39 ; or copolymerization of acrylamide with PPO-based macromonomers 40,41 ; another was N-isopropylacrylamide (NIPAM)-based amino-end functionalized macromonomer, 42 or the oligomer of NIPAM and other comonomers such as AM, AMPS, or butyl methacrylate, 43 which was grafted onto low-molecular-weight PAA backbone through a twostep process. Grafting method used in above functionalizations can control the primary structure of the copolymers and particularly the length and the molecular weight distribution of the backbone, as well as the placement of grafts along the main chain.…”

“…However, disadvantages of preparation of thermoviscosifying water-soluble polymers with such a ''grafting onto'' procedure using PEO-and NIPAMbased thermosensitive stickers were also evidenced. First, carboxylic groups was obligatorily necessary in the polymer precursor for most cases 34,[37][38][39]42,44 to couple the reactive amino-end groups; second, the grafting reaction was always conducted at a relative low polymer concentration and with rather low molecular weight parent polymers, for example, the molar mass of PAA was generally less than half million and polymer loading in the reaction system was below 4% 37 ; third, the chemicals used in the coupling reaction, such as the thermosensitive monomer NIPAM, the coupling agents dicyclohexylcarbodiimide (DCCI) and N 0 -(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC), were fairly expensive; and finally, some specific inorganic salts, mainly K 2 CO 3 , were needed to decrease T ass of PEObased thermoviscosifying polymers. 34,[37][38][39]44 These limitations may impede large-scale manufacturing of the polymers and acceptance of petroleum engineers who always desire less expensive, high polymer content, and normally high molecular weight acrylamide-based products.…”

Synthesis and rheological properties of hydrophobically modified polyacrylamides with lateral chains of poly(propylene oxide) oligomers

“…There are not many works which deal with water soluble polymers that have been modified or specifically synthesized to contain hydrophobic units with LCST behavior [8][9][10][11][12][13][14][15]. The concept of thermo-thickening polymers or polymers which undergo a viscosity increase at a given temperature was first described by Hourdet and co-workers [1,[12][13][14][15].…”