Synthesis and characterization of nanosized polylactic acid/TiO2 particle brushes by azeotropic dehydration polycondensation of lactic acid

Shaikh, Tauhid; Kaur, Harjinder

doi:10.1007/s10965-017-1412-3

Cited by 11 publications

(4 citation statements)

References 24 publications

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“…12 This charge is developed due to the presence of external siloxane groups on the HNT surface, 53 whereas a zeta potential value of À28.2 mV for PLA was due to the presence of carboxylic anionic groups at the polymer chain ends. 54,55 The zeta potential value of HP 1 is comparable with HNT, which indicated the effective and complete intercalation of PLA chains into HNT due to the lower concentration of HNT in the bionanocomposites. As a result, there was no PLA available without intercalation to effectively alter the negative charge arising from the carboxylic anionic groups at the chain ends of PLA.…”

Section: Dls and Zeta Potential Analysismentioning

confidence: 94%

RETRACTED: Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

Manju

Krishnan

Nayak

2020

Polymers and Polymer Composites

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We report the in-situ synthesis of poly(lactic acid)–halloysite nanotubes (PLA-HNT) bionanocomposites, with a perspective to improve the interaction between PLA and HNT. Three PLA-HNT bionanocomposites with different HNT weight percentages were synthesized by polycondensation, followed by azeotropic distillation technique. Fourier transform infrared spectroscopy studies indicated the existence of hydrogen bonding between terminal hydroxyl groups of PLA and Si–O–Si groups present in the outer surface of HNT. Wide-angle X-ray diffraction, 29Si- and 27Al-nuclear magnetic resonance spectroscopy analysis confirmed the intercalation of PLA into HNT. Scanning electron microscopy analysis confirmed that there was no significant agglomeration and PLA matrix was found to be embedded with HNT. Transmission electron microscopy analysis also gave ample proof to substantiate the intercalation of PLA chains into HNT. Studies on zeta potential of PLA-HNT bionanocomposites, as compared with PLA, also confirmed the interactions between PLA and HNT. Single melting peak in differential scanning calorimetry analysis indicated the existence of one form of crystalline structure.

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Section: Dls and Zeta Potential Analysismentioning

confidence: 94%

RETRACTED: Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

Manju

Krishnan

Nayak

2020

Polymers and Polymer Composites

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“…The residue left after TGA analysis was 12.2% which is much more than the amount of ZnO nanoparticles. But this is observed in degradation of many hybrid materials . This also means that the catalyst is thermally stable and can be used comfortably for reactions temperatures upto 250 °C.…”

Section: Resultsmentioning

confidence: 99%

Ultrasonication‐Assisted Synthesis of 3‐Substituted Indoles in Water Using Polymer Grafted ZnO Nanoparticles as Eco‐Friendly Catalyst

2019

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Indole based heterocyclic molecules are important and valuable structural unit that are present in various biologically active natural products, pharmaceuticals and agrochemicals. In this paper, zinc oxide nanoparticles were explored as catalyst for the synthesis of 3-substituted indoles in water via ultrasonication. The stability of ZnO nanoparticles and their dispersion in water was enhanced by grafting it with a biodegradable polymer (poly lactic acid). The proposed methodology is capable of providing desired products in good yield (83-97%) and 25 derivatives of indoles were synthesized. The green reaction metrics such as E-factor (0.16) and atom economy (97%) show that the present protocol is sustainable and economical. Also, the reactions were carried out in water under environmentally benign conditions that avoids use of any additives or hazardous solvents.

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“…The −OH group at 1627, 1630, and 1630 cm –1 on pristine TiO 2 -NP1, TiO 2 -NP2, and TiO 2 -NP3 shifted to 1635, 1627, and 1627 cm –1 , respectively, while the −CO of lactic acid at 1719–1720 cm –1 basically disappeared. This indicated that the −OH on TiO 2 NPs interacted with the −CO of lactic acid to form a grafted structure of lactic acid on TiO 2 -NPs. , Therefore, lactic acid was adsorbed onto TiO 2 NPs via complexation between the carboxyl group of lactic acid and the hydroxyl group on the particle surface. The order of oxygen content following TiO 2 -NP1 > TiO 2 -NP2 > TiO 2 -NP3 (Table S6) was in line with their order of adsorption capacity for both l -histidine and lactic acid (Figure a–c), further indicating that the hydroxyl group on TiO 2 NPs was an important adsorption site for these organic constituents.…”

Section: Resultsmentioning

confidence: 99%

Aggregation Kinetics of TiO₂ Nanoparticles in Human and Artificial Sweat Solutions: Effects of Particle Properties and Sweat Constituents

Dong

Huang

et al. 2022

Environ. Sci. Technol.

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Dermal penetration potentials of titanium dioxide nanoparticles (TiO2 NPs) may be affected by aggregation upon contact with sweat. This study investigated the aggregation kinetics of three TiO2 NPs in thirty human sweat samples and four artificial sweat standards. Effects of particle concentration, sweat type, and inorganic (sodium chloride, disodium hydrogen phosphate, and sodium dihydrogen phosphate) and organic (l-histidine, lactic acid, and urea) constituents were examined. Three TiO2 NPs remained colloidally stable in >20/30 human sweat samples and showed significant negative correlations (P < 0.01) between aggregation rates and |zeta potentials|. They aggregated rapidly over 20 min to >750 nm in three artificial sweat standards, while remained more stable in the International-Standard-Organization-pH-5.5 standard. Aggregation behaviors of three TiO2 NPs mostly followed the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory, allowing for determining their critical coagulation concentrations in inorganic constituents (15–491 mM) and Hamaker constants (3.3–7.9 × 10–21 J). Higher concentrations of particles, inorganic constituents, and l-histidine destabilized three TiO2 NPs, whereas urea inhibited aggregation. Three TiO2 NPs adsorbed organic sweat constituents via complexation with amino or carboxyl groups, with isotherms following the Langmuir model. Correlation analyses further suggested that the adsorbed organic constituents may stabilize three TiO2 NPs against aggregation in sweat by steric hindrance.

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Synthesis and characterization of nanosized polylactic acid/TiO2 particle brushes by azeotropic dehydration polycondensation of lactic acid

Cited by 11 publications

References 24 publications

RETRACTED: Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

RETRACTED: Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

Ultrasonication‐Assisted Synthesis of 3‐Substituted Indoles in Water Using Polymer Grafted ZnO Nanoparticles as Eco‐Friendly Catalyst

Aggregation Kinetics of TiO₂ Nanoparticles in Human and Artificial Sweat Solutions: Effects of Particle Properties and Sweat Constituents

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Synthesis and characterization of nanosized polylactic acid/TiO2 particle brushes by azeotropic dehydration polycondensation of lactic acid

Cited by 11 publications

References 24 publications

RETRACTED: Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

RETRACTED: Evaluation of intercalation and interaction in in-situ polymerized PLA-HNT bionanocomposites

Ultrasonication‐Assisted Synthesis of 3‐Substituted Indoles in Water Using Polymer Grafted ZnO Nanoparticles as Eco‐Friendly Catalyst

Aggregation Kinetics of TiO2 Nanoparticles in Human and Artificial Sweat Solutions: Effects of Particle Properties and Sweat Constituents

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Aggregation Kinetics of TiO₂ Nanoparticles in Human and Artificial Sweat Solutions: Effects of Particle Properties and Sweat Constituents