Influence of a Solid Surface on PNIPAM Microgel Films.

Stimuli-responsive microgels have attracted great interest in recent years as building blocks for fabricating smart surfaces with many technological applications. In particular, PNIPAM microgels are promising candidates for creating thermo-responsive scaffolds to control cell growth and detachment via temperature stimuli. In this framework, understanding the influence of the solid substrate is critical for tailoring microgel coatings to specific applications.

Thermal Behaviour of Microgels Composed of Interpenetrating Polymer Networks of Poly(-isopropylacrylamide) and Poly(acrylic acid): A Calorimetric Study.

Stimuli-responsive microgels have recently attracted great attention in fundamental research as their soft particles can be deformed and compressed at high packing fractions resulting in singular phase behaviours. Moreover, they are also well suited for a wide variety of applications such as drug delivery, tissue engineering, organ-on-chip devices, microlenses fabrication and cultural heritage. Here, thermoresponsive and pH-sensitive cross-linked microgels, composed of interpenetrating polymer networks of poly(-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc), are synthesized by a precipitation polymerization method in water and investigated through differential scanning calorimetry in a temperature range across the volume phase transition temperature of PNIPAM microgels.

Glass and Jamming Rheology in Soft Particles Made of PNIPAM and Polyacrylic Acid.

The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(-isopropylacrylamide) (PNIPAM) and polyacrylic acid () at fixed content as a function of weight concentration. We found three different rheological regimes characteristic of three different states: a Newtonian shear-thinning fluid, an attractive glass characterized by a yield stress, and a jamming state.

Chemical-Physical Behaviour of Microgels Made of Interpenetrating Polymer Networks of PNIPAM and Poly(acrylic Acid).

Microgels composed of stimuli responsive polymers have attracted worthwhile interest as model colloids for theorethical and experimental studies and for nanotechnological applications. A deep knowledge of their behaviour is fundamental for the design of new materials. Here we report the current understanding of a dual responsive microgel composed of poly(N-isopropylacrylamide) (PNIPAM), a temperature sensitive polymer, and poly(acrylic acid) (PAAc), a pH sensitive polymer, at different temperatures, PAAc contents, concentrations, solvents and pH.

Apparatus for simultaneous dynamic light scattering-small angle neutron scattering investigations of dynamics and structure in soft matter.

Dynamic Light Scattering (DLS) and Small-Angle Neutron Scattering (SANS) are two key tools to probe the dynamic and static structure factors, respectively, in soft matter. Usually, DLS and SANS measurements are performed separately, in different laboratories, on different samples, and at different times. However, this methodology has particular disadvantages for a large variety of soft materials, which exhibit a high sensitivity to small changes in fundamental parameters, such as waiting times, concentration, pH, and ionic strength.