Synthesis and phase separation of amine-functional temperature responsive copolymers based on poly(N-isopropylacrylamide)

Mai-ngam, Katanchalee; Boonkitpattarakul, Kanhokthorn; Sakulsombat, Morakot; Chumningan, Pimpun; Mai-ngam, Bunpot

doi:10.1016/j.eurpolymj.2008.11.010

Cited by 21 publications

(22 citation statements)

References 23 publications

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“…During our experiments, initial attempts to prepare poly(NIPMAm- co -APMH) microgels (μG) in pure water using a cationic initiator (V50) resulted in microgels of a very small size with poor yield (Table 1). A possible reason for the poor yield lies in unfavorable reactivity ratio between the two co-monomers, which inhibits the formation of copolymer chains that can easily collapse at high temperature [23]. Randomly positioned APMH along the copolymer chain creates sufficiently strong Coulombic repulsion between the cationic groups such that thermo-induced chain collapse is inhibited.…”

Section: Resultsmentioning

confidence: 99%

“…As a result, many free polymer chains may be formed instead of collapsed precursor particles, thereby reducing the yield of microgels, and limiting the subsequent polymer size due to a decrease in the amount of incorporated polymer/particle. Fortunately, the reactivity ratio of ionic monomers can be notably influenced by the ionic strength [23, 24]. We therefore investigated the influence of NaCl concentration on microgel preparation.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and physicochemical properties of cationic microgels based on poly(N-isopropylmethacrylamide)

Tong

Lyon

2010

Colloid Polym Sci

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Surfactant-free, radical precipitation co-polymerization of N-isopropylmethacrylamide (NIPMAm) and the cationic co-monomer N-(3-aminopropyl) methacrylamide hydrochloride (APMH) was carried out to prepare microgels functionalized with primary amines. The morphology and hydrodynamic diameter of the microgels were characterized by atomic force microscopy (AFM) and photon correlation spectroscopy (PCS), with the effect of NaCl concentration and initiator type on the microgel size and yield being investigated. When a V50-initiated reaction was carried out in pure water, relatively small microgels (~160 nm diameter) were obtained in low yield (~20%). However, both the yield and size increased if the reaction was carried out in saline or by using APS as initiator instead of V50. Stable amine-laden microgels in the range from 160 nm to 950 nm in diameter with narrow size distributions were thus produced using reaction media with controlled salinity. Microgel swelling and electrophoretic mobility values as a function of pH, ionic strength and temperature were also studied, illustrating the presence of cationic sidechains and their influence on microgel properties. Finally, the availability of the primary amine groups for post-polymerization modification was confirmed via modification with fluorescein-NHS.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis and physicochemical properties of cationic microgels based on poly(N-isopropylmethacrylamide)

Tong

Lyon

2010

Colloid Polym Sci

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“…The thermal response of PNIPAM microgels is also different when using different initiators. Phase transition of AIBN-initiated PNIPAM microgels starts from 29 C, whereas KPS-initiated one starts from higher temperature reaching 34 C. With increasing temperature, the mean diameter of PNIPAM microgels based on AIBN first decreases until 29 C, and then increases, whereas that of KPSinitiated PNIPAM microgels decreased sharply in a narrow temperature range of [31][32][33] C, and then reached a stable value. The reason for the differences of PNIPAM microgels can be attributed to different surface groups of microgels that come from residues of initiator.…”

Section: Resultsmentioning

confidence: 91%

“…The reason is that with increasing temperature, the polymer chains first become curling and shrinking, and the mean diameter of microgels decreases, but the repellency between initiator AIBN fragment and -NH always exist, so when polymer chains shrink to a certain extent, the repelling force would play a major role and the mean diameter of microgels increases. Oppositely, it was reported 9,10,[20][21][22] that when KPS was used as initiator, the mean diameter of PNI-PAM microgels decreased sharply in a narrow temperature range of [31][32][33] C, and then reached constant. The schematic illustrations for surface groups of PNIPAM microgels based on different initiators are shown in Scheme 2.…”

Section: Thermal Response Of Pnipam Microgelsmentioning

confidence: 97%

“…Perhaps the most extensively investigated class of responsive polymers are temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM), which exhibits a phase transition named lower critical solution temperature (LCST) around [32][33][34] C. [1][2][3] In aqueous solution, PNI-PAM undergoes a reversible phase transition caused by the coilto-globule transition close to its LCST. When the environmental temperature is below the LCST, PNIPAM adsorbs much water and exhibits a swollen and hydrophilic state, whereas above the LCST; it becomes hydrophobic because of expelling free water inside the polymer network and demonstrates abrupt volume shrinkage.…”

Section: Introductionmentioning

confidence: 99%

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Effects of end groups on the thermal response of poly(N‐isopropylacrylamide) microgels

Chen

Jiang

Sun

2013

J of Applied Polymer Sci

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Poly(N-isopropylacrylamide) (PNIPAM) microgels were prepared through soap-free emulsion polymerization using 2, 2 0 -azobisobutyronitrile and potassium persulfate as initiator respectively. The thermal response of microgels was researched by measuring the transmittance and the hydrodynamic diameter of the microgels at different temperatures. The result shows that the different structure of the end groups of polymer that come from residues of initiator result in the different thermal response of PNIPAM microgels. The LCST (lower critical solution temperature) of AIBN-initiator microgels is 5 C lower than that of the KPS-initiator microgels, whereas the AIBN-initiated PNIPAM microgels have better thermal response sensitivity. The scanning electron microscope characterization shows that the morphology of AIBN-initiated PNIPAM microgels is more regular than that of KPS-initiated. Furthermore, the T g of the microgels was measured by differential scanning calorimeter and the result indicates that the end groups influences the T g of microgels severely. This work demonstrated that the hydrophobic end group coming from initiators can decreases the LCST of PNIPAM microgels and increases the thermal response sensitivity, which providing a newly simple but effective method to regulate the thermal response of PNIPAM microgels.

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Preparation and thermal response behavior of poly(N‐isopropylacrylamide‐co‐a crylic acid) microgels via soap‐free emulsion polymerization based on AIBN initiator

Chen¹,

Jiang²,

Dan³

2011

J of Applied Polymer Sci

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Poly(N-isopropylacrylamide-co-acrylic acid) (poly(NIPAM-co-AA)) microgels with different copolymer compositions were prepared through soap-free emulsion polymerization at 80 C, and 2, 2 0 -azobisisobutyronitrile (AIBN) was used as initiator. Scanning electron microscope (SEM) characterization shows that the prepared microgels are regular and smooth and not easy to distort. Result of1 H-NMR characterization shows that with increasing of the initial concentration of AA (AA in feed), the AA content in polymer chains increases. The thermal response of microgels latex was investigated by UV-3010 spectrophometer through detecting the transmittance of the latex at different temperature in the range of 190-900 nm. The thermal response of the poly(NIPAM-co-AA) microgels was tested by dynamic light scattering (DLS). The results show that with the increase of AA content in polymer chains, the low critical solution temperature (LCST) of microgels latex first decreases and then increases. Still, with increasing of AA in poly(NIPAM-co-AA) microgels, the LCST of microgels first increases and then decreases. The basic reasons causing the changes of LCST of microgels latex and microgels are interpreted clearly in this article from the perspective of hydrogen bonding interaction.

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Synthesis and phase separation of amine-functional temperature responsive copolymers based on poly(N-isopropylacrylamide)

Cited by 21 publications

References 23 publications

Synthesis and physicochemical properties of cationic microgels based on poly(N-isopropylmethacrylamide)

Synthesis and physicochemical properties of cationic microgels based on poly(N-isopropylmethacrylamide)

Effects of end groups on the thermal response of poly(N‐isopropylacrylamide) microgels

Preparation and thermal response behavior of poly(N‐isopropylacrylamide‐co‐a crylic acid) microgels via soap‐free emulsion polymerization based on AIBN initiator

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