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...

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...

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 Transient electronics that disintegrate via material dissolution or depolymerization under certain stimuli have great potential in biomedical and military applications. The triboelectric nanogenerator (TENG), an emerging mechanical energy harvesting technology with flexibility choices, is promising offering transient power sources. Previously reported harvesters using biodegradable polymers require solution‐based degradation limited applications non‐biological scenarios. A short...

ABSTRACT The study and development of transient devices is an emerging field where the disposal a device after use desired to avoid reverse engineering minimize environmental impact. Polyaldehydes with phototriggers have been investigated because radiation wavelength can be adjusted meet application. Polynuclear aromatic hydrocarbons (PAHs) were used as optical sensitizer for photoacid generators (PAGs). Photoinduced electron transfer (PET) iodonium‐based PAG was expand spectral sensitivity...

Metastable poly(phthalaldehyde) (PPHA) can be triggered to depolymerize under visible light by incorporation of photosensitive compounds, such as a photoacid generator (PAG), which generate strong acid in situ. However, compounds thermally unstable and have limited shelf life, causing inadvertent device triggering. It also difficult fabricate components that are because special lighting conditions needed. In this paper, nonphotosensitive PPHA films were formed made at the point use. This...

Poly(phthalaldehyde) (PPHA) can be used as a structural material in transient devices and photo‐catalytically depolymerized at the end of device life by use photo‐acid generator (PAG). However, degradation requires presence radiation source mission. It has been found that onset PPHA depolymerization after PAG photo‐exposure delayed incorporation particular weak bases PPHA/PAG mixture. This method allows for activation prior to or during deployment when is under full user control. The...

A nanoporous epoxy film was formulated by using chemically modified epoxide-terminated polypropylene carbonate (ePPC) as the porogen in an resin formulation. The ePPC grafted onto styrene maleic anhydride (SMA) copolymer and further used to crosslink with poly(bisphenol diglycidyl ether) (pBPADGE). SMA-pBPADGE crosslinking initiated a tertiary amine catalyst. After curing of pBPADGE film, thermally decomposed created volatile, small molecules that diffused through leaving film. pore size...

Abstract Epoxide functionalized poly(propylene carbonate) (ePPC) was included in an epoxy resin formulation and thermally decomposed to create nanoporous film. The dielectric constant of the porous lower than control. introduction 30% porosity lowered from 3.78 2.76. A postporosity chemical treatment further constant. Hexamethyldisilazane (HMDS) used terminate pore walls with hydrophobic silane layer reduce both tangent loss epoxy. Two different styrene maleic anhydride crosslinking agents...

Lowering the dielectric constant of interconnect, substrates and boards for electronic devices is needed to achieve faster switching speed smaller device packages. A feasible way reduce existing material by introducing porosity within film. The density pores pore size play an important role in determining mechanical property electrical An increase fraction leads lower constant. However, higher can deteriorate properties. Therefore, it a balance between In this study, low molecular weight...

Epoxide functionalized poly(propylene carbonate) was included in an epoxy resin formulation and thermally decomposed to create nano-porous films. The dielectric constant of the porous lower than control. introduction 30% porosity lowered from 3.78 2.76. A post-porosity chemical treatment further constant. Hexamethyldisilazane used terminate pore walls with hydrophobic silane layer reduce both tangent loss epoxy. Two different styrene maleic anhydride crosslinking agents were formulation,...