Poly(vinyl ethers) as building blocks for new materials

Goethals, Eric J.; Reyntjens, Wouter; Lievens, Serge

doi:10.1002/masy.19981320108

Cited by 29 publications

(18 citation statements)

References 9 publications

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“…Although these polymer networks show two independent dual-shape effects using either T m,PEG or T m,PCL , they do not show a triple-shape effect. A variety of approaches for polymer networks with two thermal transitions get a dual-shape effect, but none of them has demonstrated the triple-shape effect (3,8,18,19) …”

Section: Resultsmentioning

confidence: 99%

Polymeric triple-shape materials

Bellin

Kelch

Langer

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

460

382

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Shape-memory polymers represent a promising class of materials that can move from one shape to another in response to a stimulus such as heat. Thus far, these systems are dual-shape materials. Here, we report a triple-shape polymer able to change from a first shape (A) to a second shape (B) and from there to a third shape (C). Shapes B and C are recalled by subsequent temperature increases. Whereas shapes A and B are fixed by physical cross-links, shape C is defined by covalent cross-links established during network formation. The triple-shape effect is a general concept that requires the application of a two-step programming process to suitable polymers and can be realized for various polymer networks whose molecular structure allows formation of at least two separated domains providing pronounced physical cross-links. These domains can act as the switches, which are used in the two-step programming process for temporarily fixing shapes A and B. It is demonstrated that different combinations of shapes A and B for a polymer network in a given shape C can be obtained by adjusting specific parameters of the programming process. Dualshape materials have already found various applications. However, as later discussed and illustrated by two examples, the ability to induce two shape changes that are not limited to be unidirectional rather than one could potentially offer unique opportunities, such as in medical devices or fasteners.active polymer ͉ polymer network ͉ shape-memory polymer ͉ stimuli-sensitive polymer ͉ two-step programming process A rubber band, which is a polymer network, can be elastically deformed and will snap back into its original shape as soon as the external stress is released. Polymer networks in their rubbery state consist of covalently cross-linked flexible polymer chains that are oriented from a coiled state during deformation. The recovery of the original shape is driven by regaining the entropy that was lost when chains were oriented (1). Primarily, the shape of a polymer network is defined by its chemical cross-links (netpoints). Depending on the type of chain segments, different macroscopic domains can be formed having individual transition temperatures (T trans ), like glass transition (T g ) and melting (T m ) temperatures (2). When a polymer network is cooled below a T trans of a specific domain, this domain is solidified and in this way forms physical cross-links. These physical cross-links can dominate the netpoints, so that a new shape can be fixed. In dual-shape materials (3-8), which have found various applications (9-12), this effect is used for temporary fixation of a second shape by deformation of the polymer network and subsequent cooling under stress. The original, memorized shape can be recovered by reheating above T trans .As a structural concept for triple-shape polymers, we selected polymer networks able to form at least two segregated domains. Although the original shape (C) is defined by netpoints resulting from the cross-linking reaction, shapes A and B are created by ...

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Section: Resultsmentioning

confidence: 99%

Polymeric triple-shape materials

Bellin

Kelch

Langer

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

460

382

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“…The polymerizations were carried out in toluene with acetal/trimethylsilyl iodide (TMSI) as initiator system and ZnI 2 as activator which is known to produce living vinyl ether polymerizations. [16][17][18][19][20][21] In Figure 1, the preparation of the different block copolymers using a mono-and bifunctional initiating system is depicted.…”

Section: Synthesis Of Block Copolymersmentioning

confidence: 99%

Block Copolymers of Methyl Vinyl Ether and Isobutyl Vinyl Ether With Thermo‐Adjustable Amphiphilic Properties

Verdonck

Goethals

Prez

2003

Macro Chemistry & Physics

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The thermo‐adjustable hydrophilic/hydrophobic properties of AB, ABA and BAB block copolymers in which A is poly(methyl vinyl ether) (PMVE) and B is poly(isobutyl vinyl ether) (PIBVE) have been investigated. The block copolymers were prepared by “living” cationic polymerization using sequential addition of monomers. The polymerizations were carried out with the system acetal/trimethylsilyl iodide as initiator and ZnI2 as activator. The initiating system based on diethoxyethane leads to AB block copolymers whereas the initiating system based on tetramethoxypropane leads to ABA or BAB triblock copolymers. Well‐defined block copolymers of different composition with controlled molecular weights up to approx. 10 000 have been prepared. When IBVE is added to living PMVE, PIBVE‐blocks form only in the presence of an additional amount of ZnI2, which is attributed to the fact that part of the ZnI2 is inactive because of complex formation with PMVE. At room temperature, the combination of hydrophilic (PMVE) and hydrophobic (PIBVE) segments provides the copolymers with surfactant properties. Above the lower critical solution temperature (LCST) of PMVE, situated around 36 °C, the PMVE‐blocks become hydrophobic and the amphiphilic nature of the block copolymers is lost. The corresponding changes in hydrophilic/hydrophobic balance have been evaluated by investigation of the emulsifying properties of the block copolymers for water/decane mixtures as a function of the temperature. Below the LCST, the block copolymers have emulsifying properties similar to or better than those of the commercial PEO‐PPO block copolymers (Pluronic®). Either oil‐in‐water or water‐in‐oil emulsions can be obtained, depending on the polymer architecture and the water/decane volume ratio. The emulsifying properties are strongly reduced or completely lost above 40 °C. Emulsions obtained with a PMVE36‐b‐PIBVE54 block copolymer for a water/decane (v/v) ratio of 85/15 remained stable for more than six months.50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE36‐b‐PIBVE54 block copolymer at 20 °C.magnified image50/50 and a 85/15 water/decane w/o emulsion (15 g/l) with the PMVE36‐b‐PIBVE54 block copolymer at 20 °C.

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“…[1][2][3][4] The minimum requirement to achieve a TSME is to have at least an additional reversible phase transition. [8] Although SMPs that meet this requirement have been reported, [8,[15][16][17][18] only the ones reported by Bellin et al show a TSME. [8] Thus far, it has remained unclear what governs the polymer TSME besides the basic requirement of having two reversible phase transitions and a freezing mechanism.…”

Section: Introductionmentioning

confidence: 98%

Revealing Triple‐Shape Memory Effect by Polymer Bilayers

Xie¹,

Xiao²,

Cheng³

2009

Macromol. Rapid Commun.

240

235

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Bilayer polymers that consist of two epoxy dual-shape memory polymers of well-separated glass transition temperatures have been synthesized. These bilayer epoxy samples exhibit a triple-shape memory effect (TSME) with shape fixities tailorable by changing the ratio between the two layers. The triple-shape fixities of the bilayer epoxy polymers can be explained by the balance of stress between the two layers. Based on this work, it is believed that the following three molecular design criterions should be considered in designing triple-shape memory polymers with optimum TSME: 1) well-separated thermal transitions, 2) a strong interface, and 3) an appropriate balance of moduli and relative ratios between the layers (or microphases).

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Poly(vinyl ethers) as building blocks for new materials

Cited by 29 publications

References 9 publications

Polymeric triple-shape materials

Polymeric triple-shape materials

Block Copolymers of Methyl Vinyl Ether and Isobutyl Vinyl Ether With Thermo‐Adjustable Amphiphilic Properties

Revealing Triple‐Shape Memory Effect by Polymer Bilayers

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