Size Control of Hollow Polylactic Acid Microcapsules and Hollow Polyelectrolyte Microcapsules in Bubble Template Method

2011 ◽  
Author(s):  
Jay J. Molino ◽  
Hirofumi Daiguji ◽  
Fumio Takemura
Keyword(s):  
Colloidal Particles ◽  
Methylene Chloride ◽  
Size Control ◽  
Bubble Surface ◽  
Template Method ◽  
Poly Lactic Acid ◽  
Solution Ph ◽  
Polyelectrolyte Microcapsules ◽  
Allylamine Hydrochloride ◽  
Bubble Template

Biodegradable hollow poly-lactic acid (PLA) microcapsules and hollow polyelectrolyte microcapsules made of poly-allylamine hydrochloride (PAH) were synthesized by directly adsorbing these polymers to N2 (air) and CO2 microbubbles respectively, using the bubble template method. To manufacture PLA microcapsules, droplets of a solution of PLA in methylene chloride (CH2Cl2) were emulsified in water. Then by solvent diffusion, N2 microbubbles nucleated inside the droplets and PLA adsorbed to the bubble surface to form microcapsules. Likewise, for PAH microcapsules, when an aqueous solution of Na2CO3 including PAH is titrated with HCl, within a specific range 7.5 < pH < 9.0, colloidal PAH particles are formed and then adsorbs to the nucleated CO2 microbubbles. This yields to hollow PAH microcapsules. If the solution pH is outside this range, colloidal particles can no longer exist, thus no microcapsules can be synthesized. This document mainly focuses on size control of these two types of microcapsules.

Fabrication of Hollow Polyelectrolyte Microcapsules From Microbubble Templates

2009 ◽  
Author(s):  
Eitaro Matsuoka ◽  
Satoshi Muto ◽  
Hirofumi Daiguji
Keyword(s):  
Carbon Dioxide ◽  
Drug Delivery ◽  
Aqueous Solution ◽  
Surfactant Solution ◽  
Bubble Surface ◽  
Ultrasound Contrast Agents ◽  
Polyelectrolyte Microcapsules ◽  
Ultrasound Contrast ◽  
Allylamine Hydrochloride ◽  
Carbon Dioxide Co2

Hollow microcapsules made of biodegradable polymers have attracted considerable attention for ultrasound contrast agents and drug delivery system. In normal fabrication techniques, stable microbubbles are formed in a surfactant solution via ultrasound, then polyelectrolyte are adsorbed on the microbubble surface, resulting in hollow microcapsules. This document proposes a new method. First, a poly-allylamine hydrochloride (PAH) polyelectrolyte aqueous solution was adjusted at pH = 12.0. Carbon dioxide (CO2) was dissolved at 300 kPa (gage) in the polyelectrolyte solution. The pH of the solution decreased with increasing dissolved CO2, and the solution became turbid at pH = 9. The solution was then degassed at 1 atm, yielding microbubbles. The polyelectrolyte was then adsorbed on the microbubble surface and became the microcapsule shell. Very smooth spherical particulates were responsible of this. These particles were microbubbles and not aggregation of polyelectrolyte molecules; however, the particles did not coalesce, nor diffused into the solution, and were more stable compared to bubbles. Fluorescent analysis revealed that these particles were polyelectrolyte adsorbed to the bubble surface. This method was successfully used to fabricate hollow PAH polyelectrolyte microcapsules from microbubble templates without surfactants.

Direct observation of the attachment behavior of hydrophobic colloidal particles onto a bubble surface

Soft Matter ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 695-702
Author(s):  
Nozomi Arai ◽  
Satoshi Watanabe ◽  
Minoru T. Miyahara ◽  
Ryoichi Yamamoto ◽  
Uwe Hampel ◽  
...  
Keyword(s):  
Contact Angle ◽  
Direct Observation ◽  
Single Particle ◽  
Colloidal Particles ◽  
Bubble Surface ◽  
Static Contact Angle ◽  
Attachment Behavior ◽  
Static Contact ◽  
Hydrophobic Particle

This article addresses the attachment behavior of a single particle onto a bubble from a microscopic view, in which a hydrophobic particle abruptly “jumps into” a bubble to satisfy its static contact angle.

Fabrication of Hollow Polylactic Acid Microcapsules From Microbubble Templates

2009 ◽  
Author(s):  
Jay J. Molino ◽  
Shingo Takada ◽  
Hirofumi Daiguji ◽  
Fumio Takemura
Keyword(s):  
Polylactic Acid ◽  
Room Temperature ◽  
Methylene Chloride ◽  
Nile Red ◽  
Bubble Surface ◽  
Poly Vinyl Alcohol ◽  
Microscope Imaging ◽  
Series Of Experiments ◽  
Radius Size

Hollow polylactic acid (PLA) microcapsules from microbubbles templates are being generated inside methylene chloride (CH2Cl2) droplets formed in a poly-vinyl alcohol aqueous solution (PVAaq). By stably keeping the microbubbles, PLA can absorb to the bubble surface and become the shell of the microcapsules. It is desired to accurately control the final microcapsule radius size. Thus, in the following document, details on a series of experiments that aim to control the microcapsule final radius are covered. In situ, microscope imaging (ECLIPSE Ti-E, Nikon Corporation, Tokyo, Japan) was used to analyze the final radius size. PLA was also stained with Nile Red (excites at 485 nm, emits at 525 nm) for fluorescence visualization. These procedures allowed the verification of the parameters that influences the final microcapsule size. Experiments were performed at room temperature. Herein, details on the experimental arrangement, results and justification for how each parameter affects the final microcapsule radius.

scholarly journals Poly(lactic acid)/lignin blends prepared with the Pickering emulsion template method

2019 ◽  
Vol 110 ◽  
pp. 378-384 ◽  
Author(s):  
Xiang Li ◽  
Nóra Hegyesi ◽  
Yunchong Zhang ◽  
Zhiping Mao ◽  
Xueling Feng ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Pickering Emulsion ◽  
Template Method ◽  
Poly Lactic Acid

scholarly journals The Discovery of the Buffer Capacity of Various Types of Polyelectrolyte Microcapsules

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4026
Author(s):  
Alexey V. Dubrovskii ◽  
Aleksandr L. Kim ◽  
Egor V. Musin ◽  
Bulat R. Ramazanov ◽  
Sergey A. Tikhonenko
Keyword(s):  
Aqueous Solution ◽  
Acidic Medium ◽  
Buffer Capacity ◽  
Colloidal Particles ◽  
Polystyrene Sulfonate ◽  
Alkaline Ph ◽  
Polyelectrolyte Microcapsules ◽  
Ph Values ◽  
Micron Size ◽  
Oppositely Charged

Polyelectrolyte microcapsules, which are obtained by the method of alternate adsorption of oppositely charged polyelectrolytes onto colloidal particles of micron size, are widely used in science and industry. Nevertheless, the properties of microcapsules are still poorly understood. In particular, there is no information in the literature on the buffer capacity. However, information on the presence of a buffer capacity and an understanding of its mechanisms can both simplify the use of microcapsules and expand the scope of their application. In this regard, the buffer capacity of various types of microcapsules was studied. It was found that polyelectrolyte microcapsules consisting of polyallylamine, and polystyrene sulfonate have a buffer capacity. In addition, in an acidic medium, the buffer capacity of microcapsules containing BSA is significantly greater than that of microcapsules without protein. This is due to the fact that BSA contributes to the buffering of microcapsules. Differences in the behaviour of the buffer capacity of microcapsules with the composition (PAH/PSS)3 and (PSS/PAH)3 were found. In addition, a hypothesis has been proposed that regions of unbound polyallylamine are responsible for the buffering properties of polyelectrolyte microcapsules. This hypothesis is confirmed by the fact that incubation of microcapsules in 0.5 M NaCl increases the amount of unbound polyallylamine, which leads to an increase in the buffer capacity of microcapsules at alkaline pH values higher than the buffer capacity of capsules in an aqueous solution.

Bubble-template synthesis of WO3·0.5H2O hollow spheres as a high-activity catalyst for catalytic oxidation of benzyl alcohol to benzaldehyde

CrystEngComm ◽  
2019 ◽  
Vol 21 (6) ◽  
pp. 1026-1033 ◽  
Author(s):  
Huixiang Wang ◽  
Xiaobo Ren ◽  
Zhong Liu ◽  
Dong Jiang ◽  
Baoliang Lv
Keyword(s):  
High Activity ◽  
Benzyl Alcohol ◽  
Catalytic Oxidation ◽  
Template Synthesis ◽  
Hollow Spheres ◽  
Template Method ◽  
Oxidation Of Benzyl Alcohol ◽  
Bubble Template ◽  
Activity Catalyst

Well-shaped WO3·0.5H2O hollow spheres are successfully prepared by a facile bubble-template method and they show high activity in catalytic oxidation of benzyl alcohol to benzaldehyde.

Effect of PEG on Stability of Alkalinity Silica Sol

2011 ◽  
Vol 399-401 ◽  
pp. 2314-2317
Author(s):  
Juan Wang ◽  
Ming Sun ◽  
Bao Hong Gao ◽  
Ru Wang ◽  
Yu Ling Liu
Keyword(s):  
Molecular Weight ◽  
Colloidal Particles ◽  
Colloidal Stability ◽  
Silica Sol ◽  
Kinetic Stability ◽  
Solution Ph ◽  
Factors Affecting ◽  
Main Factors ◽  
Silica Dispersion ◽  
The Stability

It is known that the rate of coagulation depends mainly on the stability of the colloidal particles and that the solution pH and potential are the main factors affecting the colloidal stability. The stability of dispersion (the ability of the dispersion to resist coagulation) may be related to its kinetic stability, which in turn depends on the force barrier preventing collision between the particles and thus preventing their coagulation. The addition of surfactant can change the pH and the potential of silica sol. So PEG is select to improve the stability of silica sol. The results presented here show that surfactant, PEG, has a strong consequence on the stability of silica dispersion. With the molecular weight increasing, the stability of silica sol is weakening.

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