Thermoresponsive Properties of Poly[oligo(ethylene glycol) sorbate]s Prepared by Organocatalyzed Group Transfer Polymerization

Abstract

The current contribution presents the synthesis of poly[oligo(ethylene glycol) sorbate]s (PREG m Ss) by the t-Bu-P 4catalyzed group transfer polymerization (GTP) method, their postpolymerization modification at the backbone double bond, and thermoresponsive properties in aqueous solution. Four oligo(ethylene glycol) sorbate monomers (REG m Ss), including 2-(2methoxyethoxy)ethyl sorbate (MeEG 2 S), 2-(2-(2-methoxyethoxy)ethoxy)ethyl sorbate (MeEG 3 S), 2-(2-(2-ethoxyethoxy)ethoxy)ethyl sorbate (EtEG 3 S), and 2-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)ethyl sorbate (MeEG 4 S ), are newly designed to study the thermoresponsive properties of their related polymers. The t-Bu-P 4 -catalyzed GTP of REG m S only proceeds in a 1,4-regioselective addition manner to quantitatively produce the backbone trans-rich (ca. 80%) PREG m S. The complete hydrogenation and epoxidation of the backbone double bonds result in hydrogenated and epoxidized polymers (PREG m S-H 2 and PREG m S-epoxy, respectively), which have different main-chain structures and rigidity from their parent PREG m S. Given the 1,4-substituted structure of a sorbate monomer, the chemical structure determination of PREG m S-H 2 by 13 C NMR spectra demonstrates that the above polymers have an erythro-rich (ca. 60%) structure in diastereochemistry and a diisotactic/disyndiotactic ratio around 1:1 in stereoregularity. The thermoresponsive properties of PREG m S, PREG m S-H 2 , and PREG m S-epoxy in aqueous solutions are studied in detail from various aspects in terms of polymer mass concentration, molecular weight, length and end group of the oligo(ethylene glycol) side chain, and main-chain structure by turbidity, 1 H NMR spectroscopy, and dynamic light scattering (DLS) methods, which are discussed below.

Group‐Transfer Polymerization‐Induced Self‐Assembly (GTPISA) in Non‐polar Media: An Organocatalyzed Route to Block Copolymer Nanoparticles at Room Temperature

“…Therefore, polymer chain ends simply consist of C−H bonds after workup. Over the last 15 years, the scope of GTP has been broadened through the use of a variety of organic catalysts, such as N ‐heterocyclic carbenes (NHCs) or super strong Brønsted phosphazene bases, or strong Brønsted acids (e.g., bis(trifluoromethanesulfonyl)imide) [64–74] . Synthesis of non‐aqueous dispersions of poly(methyl methacrylate) (PMMA)‐based nanoparticles by GTP was reported since 1995.…”

“…Over the last 15 years, the scope of GTP has been broadened through the use of a variety of organic catalysts, such as N-heterocyclic carbenes (NHCs) or super strong Brønsted phosphazene bases, or strong Brønsted acids (e.g., bis(trifluoromethanesulfonyl)imide). [64][65][66][67][68][69][70][71][72][73][74] Synthesis of nonaqueous dispersions of poly(methyl methacrylate) (PMMA)-based nanoparticles by GTP was reported since 1995. This was achieved by GTP of MMA or MMA and ethyleneglycol dimethacrylate (EDMA) in dispersion in nheptane using polystyrene-b-poly(ethene-alt-propene) as dispersing agent, 1-methoxy-1-(trimethylsiloxy)-2-methylprop-1-ene (MTS) as initiator and tetrabutylammonium fluoride (TBAF) or tetrabutylammonium cyanide (TBAC) as catalyst.…”

Self-assembly and salt-induced thermoresponsive properties of amphiphilic PEG/cation random terpolymers in water

“…8 Lower critical solution temperature (LCST)-type thermoresponsive polymers can switch the solubility in water or organic solvents upon heating: the homogeneous polymer solution is turbid or phase-separated upon heating above the cloud point (Cp) temperature and reversibly becomes homogeneous upon cooling below the Cp. Various LCST-type thermoresponsive polymers [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] have been designed and developed for targeted thermoresponse, func-tions, and applications, e.g., poly(N-isopropylacrylamide) (PNIPAM), [10][11][12][13][14] Pluronics, [15][16][17] and poly(ethylene glycol) (PEG) or poly(ethylene oxide) (PEO)-based compounds and (co) polymers. [18][19][20][21][22][23] Polymers with LCST-type solubility in water mostly consist of both hydrophilic units and hydrophobic units.…”

“…Various LCST-type thermoresponsive polymers [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] have been designed and developed for targeted thermoresponse, func-tions, and applications, e.g., poly(N-isopropylacrylamide) (PNIPAM), [10][11][12][13][14] Pluronics, [15][16][17] and poly(ethylene glycol) (PEG) or poly(ethylene oxide) (PEO)-based compounds and (co) polymers. [18][19][20][21][22][23] Polymers with LCST-type solubility in water mostly consist of both hydrophilic units and hydrophobic units. The thermoresponsive solubility is caused by the dehydration of polymer chains in water by changing the affinity or interaction of water molecules with the hydrophilic units.…”

“…, poly( N -isopropylacrylamide) (PNIPAM), 10–14 Pluronics, 15–17 and poly(ethylene glycol) (PEG) or poly(ethylene oxide) (PEO)-based compounds and (co)polymers. 18–23 Polymers with LCST-type solubility in water mostly consist of both hydrophilic units and hydrophobic units. The thermoresponsive solubility is caused by the dehydration of polymer chains in water by changing the affinity or interaction of water molecules with the hydrophilic units.…”