A biodegradable shape-memory nanocomposite with excellent magnetism sensitivity

Abstract

This paper reports a kind of biodegradable nanocomposite which can show an excellent shape-memory property in hot water or in an alternating magnetic field with f = 20 kH and H = 6.8 kA m(-1). The nanocomposite is composed of crosslinked poly(epsilon-caprolactone) (c-PCL) and Fe(3)O(4) nanoparticles. The crosslinking reaction in PCL with linear molecular structure was realized using benzoyl peroxide (BPO) as an initiator. The biocompatible Fe(3)O(4) magnetite nanoparticles with an average size of 10 nm were synthesized according to a chemical coprecipitation method. The initial results from c-PCL showed crosslinking modification had brought about a large enhancement in shape-memory effect for PCL. Then a series of composites made of Fe(3)O(4) nanoparticles and c-PCL were prepared and their morphological properties, mechanical properties, thermodynamic properties and shape-memory effect were investigated in succession. Significantly, the photos of the shape-memory process confirmed the anticipatory magnetically responsive shape-recovery effect of the nanocomposites because inductive heat from Fe(3)O(4) can be utilized to actuate the c-PCL vivification from their frozen temporary shape. All the results imply a very feasible method to fabricate shape-memory PCL-based nanocomposites since just a simple modification is required. Additionally, this modification would endow an excellent shape-memory effect to all other kinds of polymers so that they could broadly serve in various fields, especially in medicine.

The Mechanical Properties of Nanowires

“…the OM‐based resonance test was used for characterizing the elastic modulus of NWs in an accurate manner. In this method, the vibration spectra of a NW cantilever were obtained using optical interferometry, and the elastic modulus of NWs can thus be derived from the Euler–Bernoulli beam theory 151, 152, 153, 154. Detail information on this method will be introduced in Section 2.5.…”

“…The eigenmodes and corresponding quality factors of a vibrational object can then be precisely determined. SLDV techniques have recently been used to measure the vibration of nanostructures with diameters smaller than 50 nm 3, 151, 152, 153, 154. The high resolution of SLDV techniques allows for a simple experimental setup.…”

Magnetic nanocomposites based on hydrogenated epoxy resin

“…Methods (i) and (ii) do not allow an adequate control of particle size and the variety of nanocomposites that can be prepared is considerably limited; using method (iii), which is the most versatile, particles can agglomerate easily when mixing with the matrix unless their surface is modified. Nanocomposites of magnetite or maghemite with a wide range of different thermoplastic polymers, from conventional polymers such as polypropylene [35], polystyrene [36][37][38], or poly(methyl methacrylate) [39], to biodegradable polymers [40,41] or even conducting polymers [42] have been prepared this way.…”

Smart Delivery Systems with Shape Memory and Self-Folding Polymers

“…So this method can be useful if shape memory polymer cannot be actuated by direct heating methods. However, Zhou et al reported that for cross-linked poly(ε-caprolactone) polymers, magnetite composite shows better reactivity to hot water than alternating magnetic field [55].…”