Synthesis, Shape‐Memory Functionality and Hydrolytical Degradation Studies on Polymer Networks from Poly(rac‐lactide)‐b‐poly(propylene oxide)‐b‐poly(rac‐lactide) dimethacrylates

Choi, N.-Y.; Kelch, Steffen; Lendlein, Andreas

doi:10.1002/adem.200600020

Cited by 82 publications

(65 citation statements)

References 29 publications

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“…[24] (Co)monomers from these established implant materials are also being employed for the development of biodegradable shape-memory polymers with a high potential for new applications in the field of minimally invasive surgery. [25][26][27] Some polymers from this family, together with other relevant degradable polyesters studied in Section 3.1, are listed in Table 1, including some thermal and mechanical properties as well as an indicative time period to complete resorption (extracted from [20,24,[28][29][30][31][32] ). It should be noticed that this table is compiled from different literature sources in which the procedures to determine the listed properties were by no means standardized.…”

Section: Basics Of Hydrolytic Degradationmentioning

confidence: 99%

Knowledge‐Based Approach towards Hydrolytic Degradation of Polymer‐Based Biomaterials

et al. 2009

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The concept of hydrolytically degradable biomaterials was developed to enable the design of temporary implants that substitute or fulfill a certain function as long as required to support (wound) healing processes or to control the release of drugs. Examples are surgical implants, e.g., sutures, or implantable drug depots for treatment of cancer. In both cases degradability can help to avoid a second surgical procedure for explanation. Although degradable surgical sutures are established in the clinical practice for more than 30 years, still more than 40% of surgical sutures applied in clinics today are nondegradable.1 A major limitation of the established degradable suture materials is the fact that their degradation behavior cannot reliably be predicted by applying existing experimental methodologies. Similar concerns also apply to other degradable implants. Therefore, a knowledge-based approach is clearly needed to overcome the described problems and to enable the tailored design of biodegradable polymer materials. In this Progress Report we describe two methods (as examples for tools for this fundamental approach): molecular modeling combining atomistic bulk interface models with quantum chemical studies and experimental investigations of macromolecule degradation in monolayers on Langmuir-Blodgett (LB) troughs. Finally, an outlook on related future research strategies is provided.

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Section: Basics Of Hydrolytic Degradationmentioning

confidence: 99%

Knowledge‐Based Approach towards Hydrolytic Degradation of Polymer‐Based Biomaterials

et al. 2009

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“…They can change their shape, hydroabsorbency, water vapor permeability, self-cleaning ability, and optical and other properties when external stimuli change. 7,8 Their shape-memory effects, including shape fixity and shape recovery, are influenced by many factors, such as the soft-segment length, hard-segment content, and thermomechanical conditions. 9,10 Generally, the softsegment phase and hard-segment domains play the roles of the reversible phase and fixed phase in the shape-memory effect, respectively.…”

Section: Introductionmentioning

confidence: 99%

Preparation of polyurethane nanofibers by electrospinning

Zhuo

Chen

et al. 2008

J of Applied Polymer Sci

103

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Polyurethane (PU) nanofibers were prepared by the electrospinning method. The process parameters, including the applied voltage, feeding rate, and solution concentration, were investigated carefully. The results showed that the resultant nanofibers, electrospun from PU/N,Ndimethylformamide (DMF) solutions, had ultrafine diameters ranging from about 700 to 50 nm. In addition, it was found that the diameters and morphology of the nanofibers were influenced greatly by the process parameters. In particular, the solution concentration played a main role in influencing the transformation of the polymer solution into ultrafine fibers, and the diameters increased with the solution concentrations increasing. Finally, it was concluded that uniform PU nanofibers without beads or curls could be prepared by electrospinning through good control of the process parameters, such as 5.0-7.0 wt % PU/DMF solutions, 10-15-kV applied voltages, and 0.06-0.08 mm/min feeding rates.

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confidence: 99%

“…Polymer samples having one T g related to a mixed phase displayed switching temperatures T sw between 12°C and 30°C with comparably high shape fixity rates from 92 % to 96 %, while shape recovery rates were significantly improved from 87 % to 99 % with increasing poly(rac-lactide) block length. [22] In this article an alternative concept for the introduction of a second amorphous phase is presented using DM as oligomeric crosslinker for polyacrylates forming amorphous AB copolymer networks. The aim is to retain the poly[(L-lactide)-ran-glycolide)] segments forming the phase with the high glass transition temperature T g,h as network component but to incorporate a second amorphous phase with a low glass transition temperature (T g,l ), which keeps the material elastic even below T g,h of the poly[(L-lactide)-ran-glycolide)]-phase.…”

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Amorphous, Elastic AB Copolymer Networks from Acrylates and Poly[(L‐lactide)‐ran‐glycolide]dimethacrylates

et al. 2008

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Shape-memory polymers (SMP) are dual shape materials, which can fix a temporary shape besides their original shape. The process of deformation under application of an external stress above a transition temperature (T trans ) and fixation by cooling below T trans is called programming. The original, permanent shape can be recovered by application of heat. [1][2][3][4][5] Heating could be realized directly by an increase in environmental temperature or indirectly by exposing to alternating magnetic fields [6,7] or illuminating with IR-light. [8] Shapememory polymers have a high innovation potential as biomaterial, especially for minimally invasive surgery. One basic concept in the development of biodegradable polymer systems with shape-memory properties is based on covalently crosslinked polymer networks, [9][10][11][12] containing switching segments from semi-crystalline poly(e-caprolactone) [10,11,13] or poly[(e-caprolactone)-co-glycolide]. [12] The latter ones enable an accelerated hydrolytic degradation because of the presence of easily hydrolizable ester bonds in the form of glycolate ester bonds. [12,14] Another approach is the development of AB copolymer photoset networks, which are obtained from poly(e-caprolactone)dimethacrylate with n-butylacrylate or cyclohexylmethacrylate by UV-crosslinking. [10,11] These polymer networks showed excellent shape-memory properties and as tested so far good tissue-compatibility, in cell culture and in vivo tests. [15][16][17][18][19] Amorphous polymer networks were developed based on poly[(L-lactide)-ran-glycolide)] chain segments. [20,21] This material is transparent and has a shape-memory capability, but its mechanical properties have to be further improved. Polymer networks from poly[(L-lactide)-ran-glycolide)]dimethacrylates (DM) tend to be brittle below the glass transition temperature T g of 55°C and are difficult to handle in the course of the network synthesis and extraction without destroying the samples. The incorporation of a second amorphous phase with a low glass transition temperature (T g,l ) into these materials, which keeps the material elastic, is a potential strategy to effectively improve the elastic properties of poly[(L-lactide)-ran-glycolide]-segment based networks. Formation of an amorphous mixed phase is supposed to allow an adjustment of the switching temperature for the shape-memory effect to a temperature range between roomand body temperature.In a first approach, to obtain dilactide-based amorphous polymer networks with increased toughness and elasticity at room temperature, multi-phase polymer networks were synthesized from amorphous and degradable ABA triblock macrodimethacrylates based on poly(rac-lactide)-b-poly(propylene oxide)-b-poly(rac-lactide). Atactic poly(propylene oxide) (PPG) with a number average molecular weight M n of 4000 g mol -1 and a low T g of -73°C formed the B-block while the molecular weight of A-blocks from poly(rac-lactide) was varied. Variation in this block length resulted in networks with a T g varying between 11°C ...

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Synthesis, Shape‐Memory Functionality and Hydrolytical Degradation Studies on Polymer Networks from Poly(rac‐lactide)‐b‐poly(propylene oxide)‐b‐poly(rac‐lactide) dimethacrylates

Cited by 82 publications

References 29 publications

Knowledge‐Based Approach towards Hydrolytic Degradation of Polymer‐Based Biomaterials

Knowledge‐Based Approach towards Hydrolytic Degradation of Polymer‐Based Biomaterials

Preparation of polyurethane nanofibers by electrospinning

Amorphous, Elastic AB Copolymer Networks from Acrylates and Poly[(L‐lactide)‐ran‐glycolide]dimethacrylates

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