Quantification of nanoparticle interactions in pure solvents and a concentrated PDMS solution as a function of solvent quality.

Using turbidity measurements, we quantified the interactions between PDMS-grafted silica nanoparticles (PDMS-g-silica) in pure solvents and a concentrated polymer solution with a focus on detecting the impact of solvent quality on graft layer stretching. This work is an extension of our previous work where we showed that interfacial wetting of the grafted polymer leads to depletion restabilization in semidilute and concentrated polymer solutions in good solvents (Dutta, N.; Green, D.

Impact of solvent quality on nanoparticle dispersion in semidilute and concentrated polymer solutions.

We investigated how solvent quality affects the stability of polymer-grafted nanoparticles in semidilute and concentrated polymer solutions, which extends our previous studies on these types of dispersions in good solvents [Langmuir 2008, 24, 5260-5269]. As discussed in the current article, dynamic light scattering (DLS) was used to quantify the diffusion of polydimethylsiloxane-grafted silica nanoparticles, or PDMS-g-silica, in bromocyclohexane as well as in PDMS/bromocyclohexane solutions. We established that bromocyclohexane is a theta solvent for PDMS by varying the temperature of the solutions with PDMS-g-silica nanoparticles and detecting their aggregation at a theta temperature of T(Θ) = 19.

Sexual maturation and physical status among the adolescent Jain girls of Jabalpur, Madhya Pradesh, India.

This cross-sectional study is aimed at understanding the nature of sexual maturation vis à vis physical status of the Jain girls in comparison with other data of India. A survey was carried out to assess the development of secondary sexual characters in the background of a purely vegetarian diet, and measurements of height and weight. The present study represents 50 individuals in each age group from 8 through 18 years of Jain girls of Madhya Pradesh (MP), India.

Nanoparticle stability in semidilute and concentrated polymer solutions.

The wetting of PDMS-grafted silica spheres (PDMS- g-silica) is connected to their depletion restabilization in semidilute and concentrated PDMS/cyohexane polymer solutions. Specifically, we found that a wetting diagram of chemically identical graft and free homopolymers predicts stability of hard, semisoft, and soft spheres as a function of the bulk free polymer volume fraction, graft density, and the graft and free polymer chain lengths. The transition between stable and aggregated regions is determined optically and with dynamic light scattering.