Research in the field of shape memory polymers has recently witnessed the introduction of increasing complexity of material response, including such phenomena as triple/multishape behavior, temperature memory, and reversible actuation. Ordinarily, such complexity in physical behaviour is achieved through comparable complexity in material composition and synthesis. Seeking to achieve a triple shape behaviour with a simple route to materials synthesis, we introduce here a method that utilizes polymerization induced phase separation (PIPS) to yield the requisite combination of microstructure and composition. Thus, two blends incorporating epoxy and poly(ε-caprolactone) were developed using commercially available reactants, one featuring a semicrystalline epoxy and the other featuring an amorphous epoxy. We show that both blends exhibited distinct transition temperatures and three modulus-temperature plateaus needed for triple shape behaviour. Despite these similarities, their physical character at room temperature is vastly different: the semicrystalline epoxy material is elastomeric and the amorphous epoxy material is highly stiff. Characterization of the triple shape behaviour revealed an ability of both systems to fix two separate deformations independently, one by PCL crystallization and a second one by epoxy crystallization or vitrification, and recover both programmed shapes separately upon heating. Given the simplicity of fabrication, we envision application as multi-shape coatings, adhesives, and films.

Thermally responsive shape memory polymers (SMPs) are typically relatively stiff due to the need to vitrify the polymer chains to fix a temporary shape. A need exists for elastomeric SMPs with mechanical properties that more closely match those of human tissue. In this communication, we present a novel approach to fabricate a fully thermoplastic elastomeric SMP. Two polymers are simultaneously electrospun, or dual-spun, forming a composite fiber mat with a controllable composition. The two polymers were chosen such that one assists in “shape fixing” and the other in “shape recovery”. We envision that the versatility and simplicity of this fabrication approach will allow for large scale production of shape memory elastomeric composites (SMECs) for a wide range of applications.

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Foams prepared from shape memory polymers (SMPs) offer the potential for low density materials that can be triggered to deploy with a large volume change, unlike their solid counterparts that do so at near-constant volume. While examples of shape memory foams have been reported in the past, they have been limited to dual SMPs: those polymers featuring one switching transition between an arbitrarily programmed shape and a single permanent shape established by constituent crosslinks. Meanwhile, advances by SMP researchers have led to several approaches toward triple- or multi-shape polymers that feature more than one switching phase and thus a multitude of temporary shapes allowing for a complex sequence of shape deployments. Here, we report the design, preparation, and characterization of a triple shape memory polymeric foam that is open cell in nature and features a two phase, crosslinked SMP with a glass transition temperature of one phase at a temperature lower than a melting transition of the second phase. The soft materials were observed to feature high fidelity, repeatable triple shape behavior, characterized in compression and demonstrated for complex deployment by fixing a combination of foam compression and bending. We further explored the wettability of the foams, revealing composition-dependent behavior favorable for future work in biomedical investigations.

Material research and development is increasingly focusing on achieving specialized functionality in materials. For example, the ability to "selfheal (SH)", or naturally repair accrued damage, is attractive because it extends the lifetime of the material by increasing resistance to damaging conditions and prolonging preservation of material properties. Additionally, shape memory (SM) materials, including SM polymers, are actively considered for their ability to change shape one or more times upon application of an external stimulus. Here, we present a polymer composite, composed of poly(vinyl acetate) (PVAc) and poly(ε-caprolactone) (PCL), exhibiting both SH and SM functionalities. In fact, the SM assists in the SH ability in a process developed by our group termed, shape memory-assisted self-healing (SMASH). The advantage of the SH composite presented here is its simple fabrication. Dual-electrospinning is used to simultaneously electrospin PVAc and PCL, achieving an interwoven polymeric composite of otherwise immiscible polymers. The dual-electrospinning method facilitates precise control of the relative weight fractions of the components, and thus allows for tuning of the material properties. Upon thermal activation, damaged PVAc-PCL composites exhibited SH under a variety of testing conditions. Furthermore, the composites exhibited impressive dual and triple SM capabilities in the dry and hydrated states, respectively. Together, the commercial availability of the components and the simplicity of preparation translate to a SMASH system that could be mass produced and used as a SH coating or alone, as a packaging material.

Self-healing materials exhibit the ability to repair and to recover their functionality upon damage. Here, we report on an investigation into preparation and characterization of shape memory assisted self-healing coatings. We built on past work in which poly(e-caprolactone) electrospun fibers were infiltrated with a shape memory epoxy matrix and delve into fabricating and characterizing a coating with the same materials, but employing a blending approach, polymerization induced phase separation. After applying controlled damage, the ability of both coatings to self-heal upon heating was investigated. In both methods, coatings showed excellent thermally induced crack closure and protection against corrosion, with the blend approach being more suitable for large-scale applications given its process simplicity. Two different approaches to the preparation of shape memory-based selfhealing coatings were compared for their ability to heal structurally and functionally by heating. These two approaches, electrospinning versus polymerization-induced phase separation were found to feature comparable and quite complete healing, with the latter system offering the advantage of facile processing.

A need exists for rheological modifiers that provide thickening for organic (oil) phases in the personal care industry. Despite such a significant need, most commercially available oil thickeners have several deficiencies, notably poor efficiency and clarity in formulations. To address this gap, we have developed a novel polyurethane‐based oil thickener (Oil‐Thickener PU) that provides significant thickening (gelation at <1 wt %) and high clarity in a range of natural oils and synthetic emollients. In this work, the structure, thickening mechanism, and viscoelastic properties of neat Oil‐Thickener PU film and Oil‐Thickener in sunflower oil gel are investigated in depth. Results show that the Oil‐Thickener PU provides thickening by forming a physically crosslinked network in oil via hydrogen bonding, resulting in a gel that is shear and temperature sensitive. Given its efficiency and uniqueness, the Oil‐Thickener PU is projected to have use in applications where a thickened organic phase is required. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46372.