The solution behavior of a series of poly(2-oxazoline)s with different side chains, namely methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, nonyl, phenyl and benzyl, are reported in ethanol-water solvent mixtures based on turbidimetry investigations. The LCST transitions of poly(2-oxazoline)s with propyl side chains and the UCST transitions of the poly(2-oxazoline)s with more hydrophobic side chains are discussed in relation to the ethanol-water solvent composition and structure. The poly(2-alkyl-2-oxazoline)s with side chains longer than propyl only dissolved during the first heating run, which is discussed and correlated to the melting transition of the polymers. Full article

Shape memory nanocomposites of polyurethane (PU)-clay were fabricated by melt mixing of PU and nano-clay. Based on nano-indentation and microhardness tests, the strength of the nanocomposites increased dramatically as a function of clay content, which is attributed to the enhanced nanoclay–polymer interactions. Thermal mechanical experiments demonstrated good mechanical and shape memory effects of the nanocomposites. Full shape memory recovery was displayed by both the pure PU and PU-clay nanocomposites. Full article

This review outlines the responsive polymer methods currently in use with their potential application to plant protection and puts forward plant-specific mechanisms as stimuli in newly devised methods for smart release of crop protection agents (CPAs). CPAs include chemicals (fungicides, insecticides, herbicides), biochemicals (antibiotics, RNA-based vaccines for plant viruses), semiochemicals (pheromones, repellents, allomones), microbial pesticides, growth regulators (insect and plant) or micronutrients, all with crop protection effects. This appraisal focuses on emerging uses of polymer nano-encapsulated CPAs. Firstly, the most interesting advances in controlled release methods are critically discussed with their advantages and drawbacks. Secondly, several plant-specific stimuli-based smart methods are anticipated for use alongside the polymer nano- or micro-capsules. These new CPA release methods are designed to (i) protect plants against infection produced by fungi or bacteria, and (ii) apply micro-nutrients when the plants need it the most. Thus, we foresee (i) the responsive release of nano- encapsulated bio-insecticides regulated by plant stress enzymes, and (ii) the delivery of micro-nutrients synchronized by the nature or intensity of plant root exudates. Such continued advances of nano-scale smart polymer-based CPAs for the protection of crops herald a “small revolution” for the benefit of sustainable agriculture. Full article

Shape memory polymers (SMP) belong to the class of stimuli-responsive materials and have generated significant research interest. Their capability to retain an imposed, temporary shape and to recover the initial, permanent shape upon exposure to an external stimulus depends on the “functional determinants”, which in simplistic terms, can be divided into structural/morphological and processing/environmental factors. The primary aim of the first part of this review is to reflect the knowledge about these fundamental relationships. In a next step, recent advances in shape memory polymer composites are summarized. In contrast to earlier reviews, studies on the impairment of shape memory properties through various factors, such as aging, compression and hibernation, lubricants, UV light and thermo-mechanical cycling, are extensively reviewed. Apart from summarizing the state-of-the-art in SMP research, recent progress is commented. Full article

The physicochemical properties of stimuli-responsive polymers change with physical or biological signals, such as pH, enzyme concentrations, and temperature. These polymers have attracted considerable attention in the field of drug delivery. The drug carrier system, which was revolutionized by the introduction of these polymers, has recently provided a new paradigm of maximizing the therapeutic activity of drugs. This review highlights recent studies regarding stimuli-responsive drug carriers tailor-made for effective cytosolic drug delivery, with particular emphasis on tumor treatment. Full article

Hybrid Lattice Particle modelling (HLPM) is an innovative particular dynamics approach that is established based on a combination of the particle modelling (PM) technique together with the conventional lattice modelling (LM) theory. It is developed for the purpose of simulating the dynamic fragmentation of solids under high strain rate loadings at macroscales with a varying Poisson's ratio. HLPM is conceptually illustrated by fully dynamic particles (or “quasi-particles”) placed at the nodes of a lattice network without explicitly considering their geometric size. The interaction potentials among the particles can employ either linear (quadratic) or nonlinear (Leonard-Jones or strain rate dependent polynomial) type as the axial/angular linkage. The defined spring constants are then mapped into lattice system, which are in turn matched with the material’s continuum-level elastic moduli, strength, Poisson's ratio and mass density. As an accurate dynamic fracture solver of materials, HLPM has its unique advantages over the other numerical techniques which are mainly characterized as easy preparation of inputs, high computation efficiency, ability of post-fracture simulation and a multiscale model, etc., This paper is to review the successful HLPM studies of dynamic fragmentation of polymeric materials with good accuracy. Polymeric materials, including nylon 6-6, vinyl ester and epoxy, are accounted for under the loading conditions of tension, indentation and punctuation. In addition, HLPM of wave propagation and wave induced fracture study is also reviewed. Full article