http://www.mdpi.com/journal/polymers/special_issues/responsive-polymers/ Dear colleagues, Due to their unique “switchable” properties, stimuli-responsive polymers have been attracting considerable attention in chemistry, chemical engineering, environment, textile, and biotechnology. In recent years, significant progresses in the stimuli-responsive polymers have been witnessed and successful applications have already been demonstrated in actuators, sensors, intelligent textiles, bio-separation and drug delivery systems. The stimuli have greatly expanded from traditional thermo-responsive to photo-responsive, chemo-responsive, etc. This is largely driven by the increasing demanding from numerous real applications, in particular in biomedical related ones, such as drug delivery and medical devices in the minimally invasive surgery. This special issue, entitled “Novel Stimuli-Responsive (co)Polymers”, aims to provide a channel to timely showcase the recent development in material science, processing and technologies, as well as applications within this exciting field. In addition, review papers are welcome to feature the progress in a particular area. Dr. Richard Fu Dr. Wei Min Huang Guest Editors Submission Information All manuscripts should be submitted to polymers@mdpi.com with a copy to the Guest Editor. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website. Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed Open Access quarterly journal published by MDPI. Please visit the Instructions for Authors page before submitting a manuscript. For the first couple of issues, to be published in 2009 and 2010, the Article Processing Charges (APC) will be waived for well-prepared manuscripts. English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections. http://www.mdpi.com/2073-4360/2/3/229/ 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. http://www.mdpi.com/2073-4360/2/3/229/ Thu, 19 Aug 2010 00:00:00 CEST Polymers 2010-08-19 2 3 Review 229 251 2073-4360 Responsive Polymers for Crop Protection 2010-08-19 doi: 10.3390/polym2030229 Serban F. Peteu Florin Oancea Oana A. Sicuia Florica Constantinescu Sorina Dinu http://www.mdpi.com/2073-4360/2/3/188/ 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. http://www.mdpi.com/2073-4360/2/3/188/ Tue, 10 Aug 2010 00:00:00 CEST Polymers 2010-08-10 2 3 Article 188 199 2073-4360 Temperature Induced Solubility Transitions of Various Poly(2-oxazoline)s in Ethanol-Water Solvent Mixtures 2010-08-10 doi: 10.3390/polym2030188 Hanneke M. L. Lambermont-Thijs Huub P. C. van Kuringen Jeroen P. W. van der Put Ulrich S. Schubert Richard Hoogenboom http://www.mdpi.com/2073-4360/2/3/120/ 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. http://www.mdpi.com/2073-4360/2/3/120/ Wed, 28 Jul 2010 00:00:00 CEST Polymers 2010-07-28 2 3 Review 120 158 2073-4360 Review on the Functional Determinants and Durability of Shape Memory Polymers 2010-07-28 doi: 10.3390/polym2030120 Thorsten Pretsch http://www.mdpi.com/2073-4360/2/2/86/ 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. http://www.mdpi.com/2073-4360/2/2/86/ Tue, 22 Jun 2010 00:00:00 CEST Polymers 2010-06-22 2 2 Review 86 101 2073-4360 Intelligent Polymeric Nanocarriers Responding to Physical or Biological Signals: A New Paradigm of Cytosolic Drug Delivery for Tumor Treatment 2010-06-22 doi: 10.3390/polym2020086 Lee Baik Oh Lee http://www.mdpi.com/2073-4360/2/2/31/ 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. http://www.mdpi.com/2073-4360/2/2/31/ Mon, 26 Apr 2010 00:00:00 CEST Polymers 2010-04-26 2 2 Article 31 39 2073-4360 Thermal-Mechanical Properties of Polyurethane-Clay Shape Memory Polymer Nanocomposites 2010-04-26 doi: 10.3390/polym2020031 Xu Fu Huang Pei Chen De Hosson Kraft Reuben http://www.mdpi.com/2073-4360/2/1/3/ 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. http://www.mdpi.com/2073-4360/2/1/3/ Thu, 25 Mar 2010 00:00:00 CET Polymers 2010-03-25 2 1 Review 3 30 2073-4360 Hybrid Lattice Particle Modelling Approach for Polymeric Materials Subject to High Strain Rate Loads 2010-03-25 doi: 10.3390/polym2010003 Wang Cheng Ostoja-Starzewski Al-Ostaz Radziszewski