Synthesis and characterization of thermally expandable PMMA-based microcapsules with different cross-linking density

Zheng

J of Applied Polymer Sci

et al. 2018

Thermally expandable microspheres (TEMs) employing poly(methyl methacrylate) (PMMA) as shell and sodium bicarbonate (NaHCO 3 ) as core were prepared by a simple method of thermally induced phase separation (TIPS). The addition of NaHCO 3 improved the foaming properties of TEMs. The effects of preparation parameters on the morphology, amount of encapsulated NaHCO 3 , and foaming properties of TEMs were studied; the parameters investigated included the quench rate, the molecular weight (M w ) and amount of PMMA, and the amount of NaHCO 3 . The results show that when 0.5 g of PMMA 50k, 3 g of NaHCO 3 , and 50 g of ethanol were used, with quenching temperature at 0 8C, the TEMs were fully spherical and the maximum expansion volume of TEMs was about 3.8 times the original volume. The expansion volume of TEMs increased with increasing amount of encapsulated NaHCO 3 , and the foaming onset temperature and temperature of complete bursting of TEMs were related to the M w of PMMA.

Section: Introductionmentioning

confidence: 99%

Simple method for preparation of thermally expandable microspheres of PMMA encapsulating NaHCO₃via thermally induced phase separation

Zheng

J of Applied Polymer Sci

et al. 2018

“…Particles size and particle size distribution of AuNPs are calculated using FE‐SEM imaging as shown in Figure . The number‐averaged particle size ( D n ), weight‐averaged particle size ( D w ) and polydispersity (PDI) are calculated according to the following equations:

D_{n} = \frac{\sum_{1}^{n} n_{i} D_{i}}{\sum_{1}^{n} n_{i}}

D_{w} = \frac{\sum_{1}^{n} n_{i} D_{i}^{4}}{\sum_{1}^{n} n_{i} D_{i}^{3}}

PDI = \frac{D_{normalw}}{D_{normaln}}

where n i and D i are the number of nanoparticles and diameter, respectively. According to the results, D n , D w and PDI are 43.2 nm, 47.9 nm and 1.107, respectively.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and investigation of dual pH‐ and temperature‐responsive behaviour of poly[2‐(dimethylamino)ethyl methacrylate]‐grafted gold nanoparticles

Mohammadi

Salami‐Kalajahi

Roghani‐Mamaqani

et al. 2017

Applied Organom Chemis

Self Cite

Gold nanoparticles (AuNPs) were synthesized by reduction of chloroauric acid (HAuCl4) aqueous solution with hydrazine monohydrate. The AuNPs were immediately treated with cysteamine to obtain amine‐functionalized nanoparticles (Au‐NH2). The reaction of Au‐NH2 with epichlorohydrin and subsequent treatment with sodium hydroxide gave epoxidized AuNPs (Au‐EP). Then, thiol‐capped AuNPs (Au‐SH) were synthesized by reaction of Au‐EP with cysteamine. A ‘grafting to’ approach was utilized to graft bromine‐terminated poly(N,N′‐dimethylaminoethyl methacrylate), synthesized via aqueous atom transfer radical polymerization, with various molecular weights (6280, 25 800, 64 200 and 87 600 g mol−1) onto Au‐SH to obtain Au‐P1, Au‐P2, Au‐P3 and Au‐P4 samples, respectively. All samples were exposed to temperature and pH variations, and Z‐average diameter was monitored using dynamic light scattering. According to the results, polymer‐grafted nanoparticles collapsed at lower temperatures with increasing solution pH for all molecular weight ranges due to deprotonation of tertiary amine groups. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, a high degree of agglomeration was observed for Au‐P4 nanoparticles in alkaline media on increasing the temperature to 55 and 65 °C.

J Biomedical Materials Res

“…Producing microspheres with narrow size distribution has been a major concern in different applications specially in drug delivery systems because of need for controlling drug release . In this field, several polymerization processes have been used, but they suffer from involving toxic surfactants (for example, microemulsion and emulsion polymerizations) or broad particle size distribution (for example, precipitation polymerization).…”

Section: Introductionmentioning

confidence: 99%

N,N'‐methylenebis(acrylamide)‐crosslinked poly(acrylic acid) particles as doxorubicin carriers: A comparison between release behavior of physically loaded drug and conjugated drug via acid‐labile hydrazone linkage

Modarresi-Saryazdi

Haddadi‐Asl

Salami‐Kalajahi

2017

Self Cite

N,N'-methylenebis(acrylamide) (MBA)-crosslinked poly(acrylic acid) (PAA) particles with low degree of cross-linking were synthesized using distillation precipitation polymerization. Size and size distribution of particles were obtained using dynamic light scattering and field emission scanning electron microscopy( and results showed that microspheres had a narrow size dispersity. Proton nuclear magnetic resonance results indicated that amount of cross-linker in structure of particles is a little more than the molar percentage of feeded MBA because of greater activity ratio of MBA than AA. pH-responsive behavior of samples was investigated using UV-vis. absorption at 480 nm where each sample showed a sudden deplete in UV absorbance at a peculiar pH. Synthesized particles were used as carriers of anti-cancer drug doxorubicin using two different approaches including physically loading of drug and drug conjugation via an acid-labile hydrazone linkage. Release results showed that in the first case, amount of released drug has an inverse relationship with the amount of cross-linker in the structure and also, by adding an acid-labile linkage, the amount of burst release decreased drastically. Also, the amount of released drug for conjugated systems was much lesser than particles with physically loaded drug. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 342-348, 2018.