Konsep Proses Pemesinan Berkelanjutan

Metal industrial machining usually strongth pressure from all sectors, ether raw material industries or user metal industries. Manufacturint process which offered to all sectors industries or companies that sustainable manufakturing consist of three main factor are efective cost, enviroment and social performance

Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic–Isotropic Phase Transition Induced by Large Strain

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic–isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order–disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator

Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic–Isotropic Phase Transition Induced by Large Strain

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic–isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order–disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator

Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic–Isotropic Phase Transition Induced by Large Strain

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic–isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order–disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator

Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic–Isotropic Phase Transition Induced by Large Strain

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic–isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order–disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator

Polymers with Dual Light-Triggered Functions of Shape Memory and Healing Using Gold Nanoparticles

Shape-memory and stimuli-healable polymers (SMP and SHP) are two types of emerging smart materials. Among the many stimuli that can be used to control SMP and SHP, light is unique because of its unparalleled remote activation and spatial control. Generally, light-triggered shape memory and optically healable polymers are different polymers and it is challenging to endow the same polymer with the two light-triggered functions because of their structural incompatibility. In this paper, we describe a general polymer design that allows a single material to exhibit both light-controlled shape memory and optical healing capabilities. We show that by chemically cross-linking a crystalline polymer and loading it with a small amount of gold nanoparticles (AuNPs), the polymer displays optically controllable shape memory and fast optical healing based on the same localized heating effect arising from the surface plasmon resonance of AuNPs. The photothermal effect controls, on the one hand, the shape memory process by tuning the temperature with respect to <i>T</i>_m of the crystalline phase and, on the other hand, activates the damage healing through crystal melting and recrystallization. Moreover, we show that these two features can be triggered separately in a sequential manner

Orientation of Azobenzene Mesogens in Side-Chain Liquid Crystalline Polymers: Interplay between Effects of Mechanical Stretching, Photoisomerization and Thermal Annealing

The interplay of the mechanically and optically induced orientation of azobenzene mesogens as well as the effect of thermal annealing was investigated for both a side-chain liquid crystalline polymer (SCLCP) and a diblock copolymer comprising two SCLCPs bearing azobenzene and biphenyl mesogens, respectively. Typically, the polymer film was first subjected to stretching in either nematic or smectic phase to yield orientation of azobenzene mesogens either parallel or perpendicular to the strain direction, then exposed to unpolarized UV light to erase the mechanically induced orientation upon the <i>trans–cis</i> isomerization, followed by linearly polarized visible light for photoinduced reorientation as a result of the <i>cis–trans</i> backisomerization, and finally heated to different liquid crystalline phases for thermal annealing. The change in orientation was monitored by means of infrared dichroism. The results have unveiled complex and different orientational behaviors for the homopolymer of poly­{6-[4-(4-methoxyphenylazo)­phenoxy]­hexyl methacrylate} (PAzMA) and the diblock copolymer of poly­{6-[4-(4-methoxyphenylazo)­phenoxy]­hexyl methacrylate}-<i>block</i>-poly­{6-[4-(4-cyanophenyl)­phenoxy]­hexyl methacrylate} (PAzMA-PBiPh). In particular, the stretching-induced orientation of the homopolymer exerts no memory effect on the photoinduced reorientation, the direction of which is determined by the polarization of the visible light regardless of the mechanically induced orientation direction in the stretched film. Moreover, subsequent thermal annealing in the nematic phase leads to parallel orientation independently of the initial mechanically or photoinduced orientation direction. In contrast, the diblock copolymer displays a strong orientation memory effect. Regardless of the condition used, either for photoinduced reorientation or thermal annealing in the liquid crystalline phase, only the initial stretching-induced perpendicular orientation of azobenzene mesogens can be recovered. The reported findings provide new insight into the different orientation mechanisms, and help understanding the important issue of orientation induction and control in azobenzene-containing SCLCPs

Multitemperature Memory Actuation of a Liquid Crystal Polymer Network over a Broad Nematic–Isotropic Phase Transition Induced by Large Strain

The shape change of a polymer actuator based on liquid crystal network (LCN) generally occurs over a relatively sharp LC-isotropic phase transition. Reported herein is the discovery of an unusual phenomenon and the enabled actuation control for LCN. The smectic phase of a LCN with mesogenic moieties on the chain backbone can be suppressed by high elongation of the specimen, which gives rise to a broad nematic–isotropic phase transition. Consequently, the actuation force and related shape of the actuator can be activated to a given degree by easily varying the temperature over a wide range (35 K for LCN prepared with 500% strain) to adjust the proportion of the order–disorder phase transition. This reversible multitemperature memory actuation can translate into many stable and interconvertible shapes with one single LCN actuator

Block Copolymer Micelles with a Dual-Stimuli-Responsive Core for Fast or Slow Degradation

We report the design and demonstration of a dual-stimuli-responsive block copolymer (BCP) micelle with increased complexity and control. We have synthesized and studied a new amphiphilic ABA-type triblock copolymer whose hydrophobic middle block contains two types of stimuli-sensitive functionalities regularly and repeatedly positioned in the main chain. Using a two-step click chemistry approach, disulfide and <i>o</i>-nitrobenzyle methyl ester groups are inserted into the main chain, which react to reducing agents and light, respectively. With the end blocks being poly­(ethylene oxide), micelles formed by this BCP possess a core that can be disintegrated either rapidly via photocleavage of <i>o</i>-nitrobenzyl methyl esters or slowly through cleavage of disulfide groups by a reducing agent in the micellar solution. This feature makes possible either burst release of an encapsulated hydrophobic species from disintegrated micelles by UV light, or slow release by the action of a reducing agent, or release with combined fast-slow rate profiles using the two stimuli

Effect of Spacer and Mesogen in Side-Chain Liquid Crystal Elastomer Structure on Reversible Actuation Behavior

A liquid crystal elastomer (LCE) actuator is capable of displaying reversible shape change through order–disorder phase transition, and it is generally prepared by aligning the mesogens (often through mechanical stretching) and then cross-linking polymer chains. Herein, a series of four side-chain LCEs are synthesized by grafting side-group mesogens onto the middle block of the styrene–butadiene–styrene (SBS) triblock copolymer. These LCEs differ either in the length of the flexible spacer linking mesogen and chain backbone or in the mesogen used in their chemical structures. By means of polarized infrared spectroscopic and X-ray diffraction (XRD) measurements, the effects of spacer and mesogen on stretching-induced orientation of mesogens are investigated. The results show that varying the length of spacer or changing the mesogen has a profound effect on the orientation direction (parallel or perpendicular to the stretching direction), orientation degree (order parameter), and orientation stability to large strain. The characteristic orientation behaviors of the side-chain LCEs are retained in their respective actuators, i.e., stretched films subjected to photo-cross-linking and thermal equilibrium in the isotropic state, and determine their reversible actuation upon heating to the isotropic phase and cooling to the LC phase. In particular, the results confirm that in order for a side-chain LCE actuator to exhibit the unusual thermally induced auxetic-like shape change, i.e., its strip contracts in both length and width on heating and extends in both directions on cooling, the LCE must have a high and stable perpendicular orientation of mesogens that can compete with the conformational change of the main chain backbone aligned parallel to the stretching direction