Polymers containing hydrogen-bonding side groups (HBGs) can form transient supramolecular networks that exhibit technologically useful viscoelastic properties. Here, we investigate how dynamic behavior of functional poly(n-butyl acrylate) melts and cross-linked is influenced by different HBGs. Random copolymers weak strong HBGs were synthesized subjected to thermal mechanical analysis. The glass transition temperature (Tg) increased nearly linearly with the HBG concentration, this effect was...

A new type of lightly crosslinked shape-memory polymer that contains reversibly associating side-groups is reported. H-bonding interactions stabilize mechanically strained states at low temperatures. The materials' shape recovery rate exhibits Arrhenius-like temperature dependence due to the dynamics H-bond dissociation.

We demonstrate a single-phase, two-way shape actuator that, in the absence of an external load, elongates upon cooling and reversibly contracts heating. In simple straightforward process, partially cross-linked, semicrystalline poly(ε-caprolactone) (PCL) network is melted, stretched to several hundred percent strain, further cross-linked. Upon removal applied elastic double adopts "state-of-ease" that retains part its former strain. When cooled, internal stress-induced crystallization causes...

ADVERTISEMENT RETURN TO ISSUEPREVNoteEnergy Storage Capacity of Shape-Memory PolymersMitchell Anthamatten*, Supacharee Roddecha, and Jiahui LiView Author Information Department Chemical Engineering, 206 Gavett Hall, University Rochester, New York 14627-1066, United States*E-mail [email protected]; tel (585) 273-5526; fax 273-1348 (M.A.).Cite this: Macromolecules 2013, 46, 10, 4230–4234Publication Date (Web):May 14, 2013Publication History Received9 April 2013Published online14 May inissue 28...

Controlling network architecture and chain connectivity is critical to understanding elastic energy storage improving performance of shape-memory polymers. Acrylate-terminated poly(caprolactones) were converted into thermoset networks by three different reactions: conventional free radical polymerization, radical-induced coupling with multifunctional thiols, base-catalyzed Michael addition thiols. The highly efficient thiol–acrylate reaction ensures that the molecular weight between...

Cross-linked elastomers containing reversibly binding side groups are capable of storing elastic energy on multiple time-scales, giving rise to shape-memory and self-healing properties. Photo-cross-linkable benzophenone were incorporated into linear macromers reversible (2-ureido-4-pyrimidinone, UPy) groups. This method enables melt-processing complex permanent shapes, samples can be prepared with much higher UPy-content. UV–vis spectroscopy was applied study the efficacy cross-linking...

ABSTRACT Shape‐memory polymers (SMPs) that respond near body temperature are attracting broad interest, especially in the biomedical fields. In this study, triggering of poly(caprolactone) SMP networks is precisely adjusted by inclusion non‐crystallizable molecular linkers and variation prepolymer weight. Longer, non‐crystalline lower weight prepolymers interfere with crystallization, lowering transition temperature. Networks prepared crystallization temperatures beneath human yet above room...

Abstract Polysiloxane elastomers represent a widely utilized soft material with excellent rubber‐like elasticity, biocompatibility, and biodurability; however, there is lack of an effective straightforward approach to manipulate the material's viscoelastic response. A facile hydrosilylation reaction employed integrate ureidopyrimidinone hydrogen‐bonding side‐groups into linear crosslinked siloxane polymers achieve biocompatible materials highly tunable relaxation timescale. Stacking H‐bonded...

The influence of smectic level ordering on domain morphology has been studied in a series monodisperse side-chain liquid-crystalline (LC) diblock copolymers. These systems, which consist polystyrene-b-methacrylate-based LC, were investigated using electron microscopy and room temperature X-ray scattering. A morphological phase diagram based volume fraction molecular weight determined for weights up to 40 000 Da. broad lamellar regime was identified that extends unusually low LC compositions....

In this report the swelling and linear viscoelastic behavior of a hydrophilic polymer containing reversibly associating hydrogen bonding side-groups will be examined. Ureidopyrimidinone (UPy) moieties self-associate to form hydrogen-bonded dimers (DDAA) in non-polar media; however, UPy water-swollen hydrogel environments is unclear. A series technologically important, poly(hydroxyethyl methacrylate) (poly(HEMA)) polymers, with varying side-group content, were prepared using reversible...

Abstract Since 2001, 3D microfabrication based on two‐photon polymerization (TPP) has drawn extensive attention and interest in biology, optics, photonics, material science, high‐energy physics. The in‐volume fabrication capability due to the threshold behavior of absorption enables TPP higher flexibility compared with other nanofabrication techniques. However, as determined by feature well various reaction dynamics, writing characteristics TPP, such throughput, accuracy, surface quality,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry and Stereoelectronics of Azines. A Solid State Study Symmetrical, (E,E)-Configured, Para-Substituted (H, F, Cl, Br, CN) Acetophenone AzinesGrace Shiahuy Chen, Mitchell Anthamatten, Charles L. Barnes, Rainer GlaserCite this: J. Org. Chem. 1994, 59, 15, 4336–4340Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published inissue 1 July...

Abstract In the past two years, papers have appeared in literature which demonstrate that matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra can be obtained from matrix‐analyte preparations been produced by grinding materials together until a powder of small particle size is obtained. present study methodology was modified and applied to an insoluble polyimide oligomer, poly(4,4′‐oxydiphenylenepyromellitimide) (POPM). Two matrix were employed this analysis,...

The synthesis of end-functionalized hydrogen-bonding polymers and the investigation their melt phase blend behavior are reported. Monofunctional telechelic ureidopyrimidinone (UPy)-functionalized poly(styrene)s poly(methyl methacrylate)s were synthesized using atom transfer radical polymerization (ATRP) followed by coupling (ATRC). Aggregation UPy end-groups in solution was observed size exclusion chromatography. effect on miscibility state studied optical microscopy differential scanning...

Fixing chain orientation within polymeric materials can impart anisotropic mechanical, optical, and electrical properties. Although macroscopic anisotropy in amorphous or liquid crystalline phases has been achieved by cross-linking thermoreversible bond shuffling under strain, these methods lack spatial temporal resolution. Here, we demonstrate a method to controllably write into polymer networks containing both permanent light-sensitive bonds. While held mechanical stress light initiates...

Abstract Shape‐memory resists capable of high‐resolution curing into arbitrarily designed structures are increasingly demanded for soft robotics, optical sensors, microscale manufacturing, and biomedicine. Amorphous, shape‐memory thiol‐vinyl networks printed using two‐photon polymerization (2PP) a simple resin formulated with commercially available reagents. The ability to print feature sizes down 200 nm is attributed the use radical‐mediated, step‐growth that quickly cross‐links resin,...

Initiated chemical vapor deposition (iCVD) of poly(glycidyl methacrylate) from supersaturated monomer is reported. Rapid film growth rates, up to 600 nm/min, were observed. Films grown exhibited distinct surface undulations. The temporal evolution features during was studied and explained by condensation followed droplet coalescence growth. High densities observed at the early times are attributed rapid polymerization within condensed liquid nuclei. Droplet nucleation resulting in...

Semicrystalline shape-memory elastomers are molded into deformable geometrical features to control adhesive interactions between and a glass substrate. By mechanically thermally controlling the deformation phase-behavior of features, we can interfacial contact area force. Results indicate that elastic energy is stored in semicrystalline state deformed be released break attractive forces, automatically separating substrate from elastomer. Our findings suggest applied various printing...

Chiral nanomaterials possess unique electronic, magnetic, and optical properties that are relevant to a wide range of applications including photocatalysis, chiral photonics, biosensing. A simple, bottom-up method create chiral, inorganic structures is introduced involves the co-assembly TiO2 nanorods with cellulose nanocrystals (CNCs) in water. To guide experimental efforts, phase diagram was constructed describe how behavior depends on CNCs/TiO2/H2O composition. lyotropic cholesteric...

For a series of side-chain liquid crystalline (LC) diblock copolymers we have investigated the overlap and morphological phase behaviors. LC thermal transitions were identified using polarized optical microscopy combined with calorimetry. Order−disorder order−order (ODT's OOT's) associated copolymer morphology located elevated temperature SAXS TEM microscopy. At low fractions, samples exhibit pure lamellar morphologies, ODT temperature, TODT, is correlated to isotropization Tiso. higher...

Conjugative effects are not significant for the conformation of diaryl-substituted azines such as 1—whether within azine unit or between aryl substituents and imino units. This was conclusion studies X-ray crystal structures quantum chemical calculations.

Abstract Sulfonated polyimides exhibit high strength, good film‐forming ability, chemical resistance, and, in their hydrated state, relatively proton conductivity. Here we report the one‐pot synthesis of sulfonated polyimide‐polysiloxane segmented copolymers through reaction a dianhydride with mixture three diamines: nonionic aromatic diamine (4,4′‐oxydianiline), (4,4′‐diamino‐2,2′‐biphenyldisulfonic acid), and telechelic diamino polysiloxane. Copolymer compositions were evaluated using 1 H...

Relating thermoreversible bond kinetics to temperature and mechanical stress is essential for the ongoing development of melt-processable, reconfigurable networks. Here, we apply dynamic analysis methods study equilibrium behavior polymer networks above their gel point. Thermoreversible Diel–Alder (DA) adducts are installed as linking groups create well-defined poly(caprolactone) Stress relaxation studies at various strains performed differentiate how influence rate breaking, i.e., retro-DA...