Journal of Polymer Science Part A: Polymer Chemistry, 2015
ABSTRACT Polymers consisting of poly(acrylic acid) (PAA) and statistical poly[(acrylic acid)-co-(... more ABSTRACT Polymers consisting of poly(acrylic acid) (PAA) and statistical poly[(acrylic acid)-co-(tert-butylacrylate)] (P(AA-co-tBA)), attached to both extremities of Jeffamine® (D series based on a poly(propylene oxide) (PPO) with one amine function at each end) using atom transfer radical polymerization (ATRP) are presented in this article. An original bifunctional amide-based macroinitiator was first elaborated from Jeffamine®. tBA polymerization was subsequently initiated from this macroinitiator. This polymerization occurs in a well-controlled manner leading to narrow molecular weights distribution. Amphiphilic copolymers were finally obtained after complete or partial hydrolysis of the PtBA blocks into PAA. The control of the partial hydrolysis of tBA units, conducted in a concentrated HCl/tetrahydrofuran mixture, is demonstrated. The properties of the triblock copolymers were preliminary investigated in aqueous solution by absorbance, DLS measurements and SEC/MALS/DV/DRI analysis as a function of temperature and pH modifications, providing evidences of thermo- and pH-sensitive self-assembly of the copolymers.
ABSTRACT alpha-Oxanorbornenyl macromonomers of poly(solketal methacrylate) were synthesized by AT... more ABSTRACT alpha-Oxanorbornenyl macromonomers of poly(solketal methacrylate) were synthesized by ATRP with molar masses ranging from 3500 to 8500 g mol(-1) and polydispersity indexes (PDi) of 1.22-1.23 prior to being polymerized via ROMP. Grubb's second generation catalyst ((IMesH(2))(CY3P)RuCl2(CHPh)) was employed to give complete conversion with PDi of approximately 1.25 obtained. Subsequent hydrolysis led to well-defined polyoxanorborneneg-poly(glycerol methacrylate) copolymers via the "grafting through" strategy with number average molar mass of 24 000-3 7 000 g mol(-1). A macromonomer with a molar mass of 6000 g mol-1 was the upper limit to obtain a complete conversion under the polymerization conditions employed.
This paper reports the synthesis of cellulose nanocrystals grafted by polystyrene chains via surf... more This paper reports the synthesis of cellulose nanocrystals grafted by polystyrene chains via surface-initiated ATRP. Naturally occurring cellulose was first hydrolyzed to obtain cellulose nanocrystals. Their surface was then chemically modified using 2-bromoisobutyryl bromide to introduce initiating sites for ATRP. A varying extent of surface modification was achieved by changing reaction conditions. Further initiation of styrene polymerization from these modified nanocrystals with a CuBr/PMDETA (N,N,N',N',N''-pentamethyldiethylenetriamine) catalytic system and in the presence of a sacrificial initiator produced polysaccharide nanocrystals grafted by polystyrene chains. A range of nanocrystals-g-polystyrene with different graft lengths (theoretical polymerization degree = 27-171) was synthesized through this method and characterized by elemental analysis, XPS, FT-IR, TEM, and contact angle measurements. We are thus able to produce cellulose nanoparticles with varying grafting densities (by altering extent of initiator surface modification) and varying polymer brush length (through polymerization control). The nanocrystals-g-polystyrene (NC-g-PS) particles were tested for their capacity to absorb 1,2,4-trichlorobenzene from water. The results obtained show that they can absorb the equivalent of 50% of their weight in pollutant compared to 30 wt % adsorption for nonmodified nanocrystals, while also displaying faster absorption kinetics.
ABSTRACT This paper reports the synthesis of a thermo-sensitive amphiphilic copolymer from linsee... more ABSTRACT This paper reports the synthesis of a thermo-sensitive amphiphilic copolymer from linseed oil and its successive engagement in micelles formation. A CROP lipoinitiator was first synthesized in two steps and engaged in the polymerization of 2-isopropyl-2-oxazoline. The physico-chemical behavior of the final lipid-b-poly(2-isopropyl-2-oxazoline) copolymer was studied. This copolymer presents a cloud point temperature of 32 °C at pH = 4.6 (in the presence of 0.1 mol L−1 NaCl) and self-organizes into well-defined micelles (10 nm) with a critical micellar concentration of 10 mg L−1. The combination of this copolymer with a pH-sensitive lipid-b-poly(acrylic acid) then allowed the preparation of mixed micelles, leading to a system sensitive to both pH and temperature modifications.
Journal of Polymer Science Part A: Polymer Chemistry, 2015
ABSTRACT Polymers consisting of poly(acrylic acid) (PAA) and statistical poly[(acrylic acid)-co-(... more ABSTRACT Polymers consisting of poly(acrylic acid) (PAA) and statistical poly[(acrylic acid)-co-(tert-butylacrylate)] (P(AA-co-tBA)), attached to both extremities of Jeffamine® (D series based on a poly(propylene oxide) (PPO) with one amine function at each end) using atom transfer radical polymerization (ATRP) are presented in this article. An original bifunctional amide-based macroinitiator was first elaborated from Jeffamine®. tBA polymerization was subsequently initiated from this macroinitiator. This polymerization occurs in a well-controlled manner leading to narrow molecular weights distribution. Amphiphilic copolymers were finally obtained after complete or partial hydrolysis of the PtBA blocks into PAA. The control of the partial hydrolysis of tBA units, conducted in a concentrated HCl/tetrahydrofuran mixture, is demonstrated. The properties of the triblock copolymers were preliminary investigated in aqueous solution by absorbance, DLS measurements and SEC/MALS/DV/DRI analysis as a function of temperature and pH modifications, providing evidences of thermo- and pH-sensitive self-assembly of the copolymers.
ABSTRACT alpha-Oxanorbornenyl macromonomers of poly(solketal methacrylate) were synthesized by AT... more ABSTRACT alpha-Oxanorbornenyl macromonomers of poly(solketal methacrylate) were synthesized by ATRP with molar masses ranging from 3500 to 8500 g mol(-1) and polydispersity indexes (PDi) of 1.22-1.23 prior to being polymerized via ROMP. Grubb's second generation catalyst ((IMesH(2))(CY3P)RuCl2(CHPh)) was employed to give complete conversion with PDi of approximately 1.25 obtained. Subsequent hydrolysis led to well-defined polyoxanorborneneg-poly(glycerol methacrylate) copolymers via the "grafting through" strategy with number average molar mass of 24 000-3 7 000 g mol(-1). A macromonomer with a molar mass of 6000 g mol-1 was the upper limit to obtain a complete conversion under the polymerization conditions employed.
This paper reports the synthesis of cellulose nanocrystals grafted by polystyrene chains via surf... more This paper reports the synthesis of cellulose nanocrystals grafted by polystyrene chains via surface-initiated ATRP. Naturally occurring cellulose was first hydrolyzed to obtain cellulose nanocrystals. Their surface was then chemically modified using 2-bromoisobutyryl bromide to introduce initiating sites for ATRP. A varying extent of surface modification was achieved by changing reaction conditions. Further initiation of styrene polymerization from these modified nanocrystals with a CuBr/PMDETA (N,N,N',N',N''-pentamethyldiethylenetriamine) catalytic system and in the presence of a sacrificial initiator produced polysaccharide nanocrystals grafted by polystyrene chains. A range of nanocrystals-g-polystyrene with different graft lengths (theoretical polymerization degree = 27-171) was synthesized through this method and characterized by elemental analysis, XPS, FT-IR, TEM, and contact angle measurements. We are thus able to produce cellulose nanoparticles with varying grafting densities (by altering extent of initiator surface modification) and varying polymer brush length (through polymerization control). The nanocrystals-g-polystyrene (NC-g-PS) particles were tested for their capacity to absorb 1,2,4-trichlorobenzene from water. The results obtained show that they can absorb the equivalent of 50% of their weight in pollutant compared to 30 wt % adsorption for nonmodified nanocrystals, while also displaying faster absorption kinetics.
ABSTRACT This paper reports the synthesis of a thermo-sensitive amphiphilic copolymer from linsee... more ABSTRACT This paper reports the synthesis of a thermo-sensitive amphiphilic copolymer from linseed oil and its successive engagement in micelles formation. A CROP lipoinitiator was first synthesized in two steps and engaged in the polymerization of 2-isopropyl-2-oxazoline. The physico-chemical behavior of the final lipid-b-poly(2-isopropyl-2-oxazoline) copolymer was studied. This copolymer presents a cloud point temperature of 32 °C at pH = 4.6 (in the presence of 0.1 mol L−1 NaCl) and self-organizes into well-defined micelles (10 nm) with a critical micellar concentration of 10 mg L−1. The combination of this copolymer with a pH-sensitive lipid-b-poly(acrylic acid) then allowed the preparation of mixed micelles, leading to a system sensitive to both pH and temperature modifications.
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