New pH-responsive linear and crosslinked functional copolymers of N-acryloyl-N′-phenyl piperazine with acrylic acid and hydroxyethyl methacrylate: synthesis, reactivity, and effect of steric hindrance on swelling

Deen, G. Roshan; Lee, T. T.

doi:10.1007/s00289-012-0770-6

Cited by 7 publications

(4 citation statements)

References 33 publications

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“…We present data from a small-angle x-ray scattering (SAXS) study of crystal growth in a slightly charged microgel system of poly(N -isopropylacrylamide) (pNIPAM) copolymerized with acrylic acid (AAc). As a result, in addition to the response to temperature changes by virtue of the pNIPAM, these particles are also pH sensitive, as AAc gets ionized at pH > 4.3 [20]. We study suspensions at a fixed pH a little above this transition, such that the particles are slightly charged and show a clear temperature response.…”

Section: Introductionmentioning

confidence: 99%

Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels

et al. 2013

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We present a small-angle x-ray scattering study of crystals formed by temperature-sensitive, swollen microgel particles consisting of poly(N-isopropylacrylamide) copolymerized with acrylic acid and 5 mol % of a cross-linker. As for hard spheres, the random hexagonal close-packed structure is predominant during crystal growth and slowly transforms toward the face-centered-cubic structure. However, a transient phase of body-centered-cubic crystal is observed in an intermediate range of effective volume fractions. We estimate that the studied suspensions are close to a transition from face-centered-cubic to body-centered-cubic structure that can be understood by the tendency of the system to maximize the excluded volume and minimize the contact area between the particles.

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Section: Introductionmentioning

confidence: 99%

Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels

et al. 2013

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“…48 Synthesis of Monomer N-Acryloyl-N 0 -ethyl piperazine (AcrNEP) The monomer AcrNEP was synthesized by reacting acryloyl chloride with N-ethyl piperazine in the presence of triethylamine at 0 C, according to the method reported earlier. 42,44…”

Section: Synthesis Of Acryloyl Chloridementioning

confidence: 99%

“…These systems show lower cytotoxicity and comparable transfection efficiencies. [37][38][39][40][41] As part of our continuous research interest in developing piperazine-based cationic polymeric materials [42][43][44][45][46] for targeted applications, in this article we report the stimuli-responsive aqueous solution properties of a new cationic linear polymer based on an ionizable heterocyclic monomer N-acryloyl-N 0ethyl piperazine (AcrNEP) and NIPAM. The ionizable monomer belongs to the class of amido-amines, which when polymerized gives a water-soluble polymer with no LCST.…”

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confidence: 99%

Influence of multiple stimuli on the lower critical solution temperature of new cationic poly(N‐acryloyl‐N′‐ethylpiperazine‐co‐N‐isopropylacrylamide) solutions

Deen

Zhen

Hao

et al. 2013

J Polym Sci B Polym Phys

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New multi-stimuli responsive cationic copolymers based on N-acryloyl-N 0 -ethyl piperazine (AcrNEP) and N-isopropylacrylamide (NIPAM) were prepared by thermal free-radical solution polymerization in dioxane at 75 C. The chemical composition of the copolymers was determined by 1 H NMR spectroscopy and was found that the copolymers were slightly rich in NIPAM content than that of AcrNEP. The reactivity of the two monomers for the copolymerization reaction was evaluated by the extended Kelen-T€ ud€ os method. The distribution of monomer sequence in the copolymer chain was estimated using the terminal copolymerization model. The maximum tendency to alternation ( 70%) was at 60 mol % of AcrNEP in the monomer feed. The copolymers were readily soluble in water at room temperature at all compositions and exhibited well-defined lower critical solution temperature (LCST) phenomenon. The influence of various stimuli such as pH, temperature, simple inorganic salts, and surfactants on the LCST of the copolymers was studied in detail. Simple inorganic salts such as sodium chloride, sodium bromide, and sodium sulfate showed a salting-out effect while sodium iodide showed a salting-in effect. The salting-out coefficient of the salts were calculated using the Sestchenow method, and the salting trend followed the order SO 4 22 > Cl 2 > Br 2 > I 2 . The divalent salt was more effective in lowering the LCST than the monovalent salts. The cationic surfactant hexadecyl trimethylammonium bromide at concentrations above the critical micelle concentration caused a gradual increase in the LCST of the copolymer solutions. The intrinsic viscosity and light scattering behavior of the copolymers in water and in sodium chloride solutions were studied in detail.

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“…These polymeric materials are obtained from new synthetic monomers containing tertiary amine functional groups [17,18,19]. This has been achieved by the following chemical synthesis approaches: (i) the copolymerization of monomers with desired functional groups [20,21,22,23,24,25], (ii) the copolymerization or combination of thermo-sensitive polymers with polyelectrolytes [26,27], (iii) the formation of inter-penetrating networks through combination of various stimuli-sensitive polymers [28,29], and (iv) the chemical synthesis and polymerization of new functional monomers [30,31].…”

Section: Introductionmentioning

confidence: 99%

Stimuli-Responsive Cationic Hydrogels in Drug Delivery Applications

Deen

Loh

2018

Gels

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Stimuli-responsive, smart, intelligent, or environmentally sensitive polymers respond to changes in external stimuli such as pH, temperature, ionic strength, surfactants, pressure, light, biomolecules, and magnetic field. These materials are developed in various network architectures such as block copolymers, crosslinked hydrogels, nanogels, inter-penetrating networks, and dendrimers. Stimuli-responsive cationic polymers and hydrogels are an interesting class of "smart" materials that respond reversibly to changes in external pH. These materials have the ability to swell extensively in solutions of acidic pH and de-swell or shrink in solutions of alkaline pH. This reversible swelling-shrinking property brought about by changes in external pH conditions makes these materials useful in a wide range of applications such as drug delivery systems and chemical sensors. This article focuses mainly on the properties of these interesting materials and their applications in drug delivery systems.

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New pH-responsive linear and crosslinked functional copolymers of N-acryloyl-N′-phenyl piperazine with acrylic acid and hydroxyethyl methacrylate: synthesis, reactivity, and effect of steric hindrance on swelling

Cited by 7 publications

References 33 publications

Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels

Transient formation of bcc crystals in suspensions of poly(N-isopropylacrylamide)-based microgels

Influence of multiple stimuli on the lower critical solution temperature of new cationic poly(N‐acryloyl‐N′‐ethylpiperazine‐co‐N‐isopropylacrylamide) solutions

Stimuli-Responsive Cationic Hydrogels in Drug Delivery Applications

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