Smart Delivery Systems with Shape Memory and Self-Folding Polymers

Abstract

New generation delivery systems involve smart materials such as shape memory and self-folding polymers. Shape memory polymers revert back to their original shape above their glass transition temperatures where this temperature change can be induced conventionally, photolytically, with a lazer or magnetically depending on the composition of the material. This ability to assume original shape upon a trigger can be used in delivering drugs, DNA or cells. Self folding polymers are a new class of materials which may be composed of multilayers with different thermal expansion coefficients or with hinges that allow folding upon being triggered. These new materials allow various architectural designs of smart delivery vehicles predominantly for DNA and cells. The aim of this chapter is given shape and folding polymers and their usage for drug delivery systems.

A taxonomy of shape-changing behavior for 4D printed parts using shape-memory polymers

“…SMAs are considered to be disadvantageous due to complex production, high costs, toxicity, and limited recovery (Table 1). Therefore, SMPs and hydrogels are preferred over the use of shape-memory alloys (SMAs) [9].…”

Influence of the Salt Concentration on the Properties of Salt‐Free Polyelectrolyte Complex Membranes

“…programmed and released a temporary shape in extruded PDADMAC/PSS fibers by placing them in hot water. [22] Figure 2 shows that the materials studied here display the features necessary for shape memory, that is, elastic behavior above T g , which is necessary to recover the original (permanent) shape, [23][24][25] and a glass transition around a convenient temperature that can serve to fix a temporary shape. The shape memory behavior of films made from PEC(1.5) and PEC(0) is illustrated in Figure 5a.…”

Technological considerations for 4D printing: an overview

“…For example, SMPs and hydrogels are preferred over the use of shape memory alloys (SMAs) as SMPs have a wide range of glass transition temperatures from − 70 to 100 °C, allowing their stiffness to be tailored [30]. SMPs have the potential to achieve a shape recovery property up to 400% of plastic strain, whereas SMAs are around 7-8%.…”

“…According to Erkeçoğlu [30], the main difference between a one-way and three-way shape memory effect is that the three-way shape memory effect has one intermediate shape between its original and temporary shapes. If there is more than one intermediate shape, then this is also known as a "multiple shape memory effect", achieved by combining multiple two-way shape memory polymers with different glass transition temperatures [38]; or by heating a programmed shape memory polymer first above the glass transition temperature and then above the melting transition temperature of the switching segment [39].…”

“…The calculation for strain recovery and fixity rate is made up of R r = 100% × (ε − ε rec )/ε and R f = 100% × ε/ε load ; whereby ε = fixed strain after cooling and unloading; ε rec = strain after recovery; and ε load = maximum strain under load [33]. [30] This paper will study on the shape memory effect (SME) of shape memory polymers (SMPs).…”